Systems and methods for fluid manipulation

Abstract

By manipulating the fluid flow in the vicinity of an object such as a fuselage, a wing, or a hull, the wave drag associated with the object can be greatly reduced. This can be achieved by locally changing both the fluid flow velocity and the pressure of the fluid flow.

Description

[0001] This application claims the benefits of U.S. Provisional Application No. 62 / 749,109, filed October 22, 2018, and U.S. Provisional Application No. 62 / 751,623, filed October 28, 2018. This application relates to U.S. Application No. 16 / 101,391, filed August 10, 2018, which claims the benefits of U.S. Provisional Application No. 62 / 543,371, filed August 10, 2017; U.S. Provisional Application No. 62 / 685,295, filed June 15, 2018; U.S. Provisional Application No. 62 / 703,898, filed July 27, 2018; and U.S. Provisional Application No. 62 / 714,778, filed August 6, 2018. Each of the applications listed above is incorporated herein by reference. Background Technology

[0002] Many fluid interaction devices consume a significant amount of power at low free-flow velocities. For example, a helicopter may require twice the power to hover as it does at nominal level cruise. The propellers of conventional fixed-wing aircraft or the turbofans of commercial jet airliners consume a greater amount of power for a given thrust at lower free-flow velocities (such as those observed during takeoff) than at higher free-flow velocities (such as those observed at nominal level cruise). Similarly, a conventional open-rotor wind turbine is not necessarily capable of extracting a small amount of power from a fluid.

[0003] Attempts to mitigate the inefficiencies in thrust generation or power extraction associated with relatively low free-flow velocities are limited in effectiveness. For example, ducts can be used to increase the local free-flow velocity in propellers, helicopter rotors, or wind turbines. The extent of this increase is determined by the geometry of the duct, which is strictly limited by constraints, such as those related to flow separation. These constraints are particularly stringent for smaller free-flow velocities, where ducts are most needed. Due to these constraints, a significant impact on the local free-flow can only be achieved through ducts with large diffusers, which may be associated with excessively large wetting areas and increased weight.

[0004] Objects moving relative to a fluid (such as a fuselage) typically experience frictional or traction drag. In the prior art, attempts to minimize this traction drag are generally limited to ensuring the wetted surface of the object is as smooth as possible. In some cases, such smoothness can facilitate laminar flow on at least a portion of the wetted surface, which can help reduce viscous traction drag. However, even in the presence of laminar flow, this traction drag is considerable.

[0005] Aircraft or their components traveling at supersonic or transonic speeds typically generate shock waves, which introduce considerable drag. Ships or their components traveling in water typically generate surface waves or gravity waves, which can also introduce significant drag. The goal is to reduce the total drag exerted on an aircraft or its components by wave drag. Summary of the Invention

[0006] Some of the embodiments disclosed herein relate to fluid interaction devices, such as aircraft, ships, or land vehicles, which are susceptible to drag, and in particular wave drag.

[0007] Some embodiments relate to a system for reducing wave drag.

[0008] Some embodiments relate to a method for reducing wave drag.

[0009] In some embodiments, the outer surface may be configured to receive external fluid flow.

[0010] In some embodiments, the channel may be coupled to an outer surface and configured to receive internal fluid flow.

[0011] In some embodiments, the channel may include a fluid inlet and a fluid outlet.

[0012] In some embodiments, the channel can be configured to manipulate the internal fluid flow to reduce wave drag.

[0013] In some embodiments, the channel may include a first fluid manipulation device (“FMA”) configured to receive internal fluid flow downstream of a fluid inlet and may be further configured to change the speed and pressure of the fluid flow within the channel.

[0014] In some embodiments, the channel may include a pressure containment device (“PCA”) configured to receive internal fluid flow downstream of the first FMA.

[0015] In some embodiments, the channel may include a second FMA, which may be configured to receive internal fluid flow downstream of the PCA and upstream of the fluid outlet.

[0016] In some embodiments, the second FMA may be configured to further alter the speed and pressure of the internal fluid flow.

[0017] In some embodiments, the free flow may have a free flow velocity greater than the wave velocity of the waves within the free flow.

[0018] In some embodiments, the first FMA and / or the second FMA may include one or more of the following: a constricting catheter; a dilating catheter; a gradually expanding catheter; a propeller; a thrust generating device; and / or a force generating device.

[0019] In some embodiments, the fluid may be compressible.

[0020] In some embodiments, the fluid may be a gas, such as air, nitrogen, or carbon dioxide.

[0021] In some embodiments, the first FMA may be configured to slow down the internal fluid flow and increase the pressure relative to the free flow.

[0022] In some embodiments, the first FMA may be configured to slow the internal fluid flow to a subsonic fluid velocity.

[0023] In some embodiments, the first FMA may be configured to slow the internal fluid flow to transonic speeds.

[0024] In some embodiments, the first FMA may be configured to slow the internal fluid flow to a lower supersonic speed.

[0025] In some embodiments, the second FMA may be configured to accelerate the internal fluid flow and reduce the pressure relative to the free flow.

[0026] In some embodiments, the second FMA may be configured to accelerate the internal fluid flow to a speed substantially equal to the free flow velocity.

[0027] In some embodiments, the second FMA may be configured to accelerate the internal fluid flow to a speed greater than the free flow velocity.

[0028] In some embodiments, the second FMA may be configured to accelerate the internal fluid flow to a velocity less than the free flow velocity.

[0029] In some embodiments, the fluid may be substantially incompressible.

[0030] In some embodiments, the fluid may be water.

[0031] In some embodiments, the first FMA may be configured to accelerate the internal fluid flow and reduce the pressure of the internal fluid flow relative to the free flow, thereby reducing the cross-sectional area of ​​the internal fluid flow leaving the first FMA and entering the PCA compared to the equivalent free flow cross-sectional area.

[0032] In some embodiments, the first FMA may be configured to accelerate the flow of internal fluids, thereby reducing the total drag on the aircraft containing the system, which may include wave drag.

[0033] In some embodiments, the second FMA may be configured to slow down the internal fluid flow and increase the pressure of the internal fluid flow relative to the free flow, thereby increasing the cross-sectional area of ​​the internal fluid flow leaving the second FMA.

[0034] In some embodiments, the second FMA may be configured to slow the internal fluid flow to a speed substantially equal to the free flow velocity.

[0035] In some embodiments, the second FMA may be configured to slow the internal fluid flow to a speed greater than the free flow velocity.

[0036] In some embodiments, the second FMA may be configured to slow the internal fluid flow to a speed less than the free flow velocity.

[0037] In some embodiments, the PCA can be configured to maintain a pressure difference between the internal fluid flow within the PCA and the free flow outside the outer surface.

[0038] In some embodiments, the PCA may include a channel having a circular, rectangular, elliptical, or polygonal cross-section, and / or a straight edge, bend, elbow, or turn.

[0039] In some embodiments, the PCA may include a wing configured to generate lift and transfer net momentum to the fluid within the PCA.

[0040] In some embodiments, the PCA may include a fuselage.

[0041] In some embodiments, the PCA may include one or more of the following: an intentional momentum carrying device, an intentional momentum releasing device, a turboshaft engine, a turbofan engine, a turboprop engine, a turbojet engine, a ramjet engine, a thrust device, a drag device, a pump-jet engine, a propeller, and / or an afterburner.

[0042] In some embodiments, the PCA may include a first thrust device, wherein the first thrust device may be configured to apply a first induced velocity to the local free flow during nominal operating requirements. The first thrust device may generate a flow tube.

[0043] In some embodiments, the PCA may include a second thrust device. The second thrust device may be located in the downstream portion of the flow tube. The second thrust device may be configured to apply a second induced velocity to the local free flow. The second induced velocity at the location of the second thrust device may have a component in the opposite direction to the first induced velocity at the location of the second thrust device.

[0044] In some embodiments, the first thrust device and / or the second thrust device may include a propeller.

[0045] In some embodiments, at least a portion of the power extracted by one of the first or second thrust devices can be diverted as power to the other thrust device.

[0046] In some embodiments, the volume between the outer and inner surfaces can be at least a portion of the aircraft.

[0047] In some embodiments, the outer and inner surfaces may be configured to reduce the effect of wave drag in free-flow.

[0048] In some embodiments, the outer surface may be substantially parallel to the free flow lines.

[0049] In some embodiments, the outer surface may be an annular cylinder, wherein the first FMA may be located at the upstream end of the cylinder and the second FMA may be located at the downstream end of the cylinder.

[0050] In some embodiments, the outer surface of the aircraft may be in the shape of a conical cylinder, wherein the radius of the cylinder may decrease in the downstream direction.

[0051] In some embodiments, when viewed along the free flow direction, the cross-sectional area of ​​the outer surface can be circular, elliptical, rectangular, or polygonal.

[0052] In some embodiments, the aircraft may be configured to take off vertically and operate nominally without inducing significant wave drag.

[0053] In some embodiments, the aircraft may be configured to fly at subsonic and / or supersonic speeds in level cruise without inducing significant wave drag.

[0054] In some embodiments, the outer and inner surfaces may form an intentional momentum-carrying device, and the system may further include a boundary device. IMCA can reduce the local free-flow velocity of the boundary device relative to the free-flow velocity.

[0055] In some embodiments, the reduction in the local free-flow velocity of the boundary device can be a reduction in the velocity of the flow that is higher than the wave velocity within the local free-flow fluid.

[0056] In some embodiments, the local free-flow velocity of the boundary device can be reduced to a velocity substantially equal to the wave velocity within the local free-flow.

[0057] In some embodiments, the local free-flow velocity of the boundary device can be reduced to less than the wave velocity within the local free-flow.

[0058] In some embodiments, the local free-flow velocity of the boundary device can be reduced to a supersonic velocity within the local free-flow of the boundary device.

[0059] In some embodiments, the local free-flow velocity of the boundary device can be reduced to a transonic velocity within the local free-flow of the boundary device.

[0060] In some embodiments, the local free-flow velocity of the boundary device can be reduced to a subsonic velocity within the local free-flow of the boundary device.

[0061] In some embodiments, the boundary device may include a fuselage or a hull.

[0062] In some embodiments, the boundary device may include a wing.

[0063] In some embodiments, the boundary device may include a third FMA, which may be configured to transfer net induced velocity to the far wake of the third FIA.

[0064] In some embodiments, at least a portion of the far wake of the third FMA may be located within the channel and be at a local free-flow velocity less than the free-flow velocity due to the reduced local free-flow velocity upstream, downstream and near the third FIA.

[0065] In some embodiments, the induced velocity in the far wake of the third FIA to the third FMA can have a non-zero net component of the local free-flow within the PCA perpendicular to the downstream of the third FMA.

[0066] In some embodiments, the third FIA may be a wing that can be configured to generate lift during nominal level cruise operation.

[0067] In some embodiments, at least a portion of the wing's far wake may be located within a region of reduced local free flow within the channel.

[0068] In some embodiments, the far wake of the wing may extend outside the channel outlet and into the free flow downstream; the wingspan may be less than half the effective diameter of the channel at the wing location; and / or the wingspan may be less than one-quarter the effective diameter of the channel at the wing location.

[0069] In some embodiments, the wingspan may be less than one-tenth of the effective diameter of the channel at the wing location.

[0070] In some embodiments, the induced velocity of the far wake that can be transferred from the third FIA to the third FMA can have a non-zero net component parallel to the local free flow.

[0071] In some embodiments, the third FIA may include a fuselage or a propeller and may be configured to generate thrust or drag during nominal level cruise operation.

[0072] In some embodiments, the boundary device may be located within the flow tube formed by the leading and trailing edges of the IMCA.

[0073] In some embodiments, a first FMA may be provided.

[0074] In some embodiments, a second FMA may be provided, which may be at least partially located within the downstream flow tube of the first FMA.

[0075] In some embodiments, a pressure-retaining device (“PCA”) may be provided and may be configured to at least partially surround a flow tube passing through both the first FMA and the second FMA.

[0076] In some embodiments, the fluid may be compressible, and the first FMA may decelerate the fluid and increase its pressure, while the second FMA may accelerate the fluid and decrease its pressure. A wing may be provided within the PCA to generate lift at a lower speed and higher pressure compared to free flow.

[0077] In some embodiments, the fluid may be incompressible, and the first FMA may accelerate the fluid and reduce its pressure, while the second FMA may decelerate the fluid and increase its pressure. The lower pressure and lower cross-sectional area flow may be transmitted from the first FMA to the second FMA via the PCA through the aircraft, thereby generating less wave drag for the aircraft. Attached Figure Description

[0078] Figures 1 and 2 are cross-sectional views of existing thrust devices.

[0079] Figure 3 This is a cross-sectional view of an intentional fluid manipulation device (“IFMA”) configuration according to some embodiments.

[0080] Figure 4 This is a cross-sectional view of the IFMA configuration according to some embodiments.

[0081] Figure 5 is a cross-sectional view of a prior art fluid manipulation device.

[0082] Figure 6 This is a cross-sectional view of the IFMA configuration according to some embodiments.

[0083] Figure 7 This is a cross-sectional view of the IFMA configuration according to some embodiments.

[0084] Figure 8 and Figure 9 These are cross-sectional views and front views of IFMA configurations according to some embodiments.

[0085] Figure 10 , Figure 11 , Figure 12 and Figure 13 These are perspective views, side views, top views, and rear views configured according to some embodiments of IFMA.

[0086] Figure 14 These are sectional views, perspective views, and oblique views configured according to some embodiments of IFMA.

[0087] Figures 15 to 18 This is a perspective view of various IFMA configurations according to some embodiments.

[0088] Figures 19 to 21 This is a side view of various IFMA configurations according to some embodiments.

[0089] Figure 22 This is a cross-sectional view of a catheter device according to some embodiments.

[0090] Figure 23 This is a cross-sectional view of a catheter device according to some embodiments.

[0091] Figures 24 to 28 yes Figure 24 A cross-sectional view of the conduit device.

[0092] Figure 29 This is a cross-sectional view of a catheter device according to some embodiments.

[0093] Figure 30 and Figure 31 These are embodiments for various operating modes. Figure 29 A cross-sectional view of the conduit device. Detailed Implementation

[0094] The term "effective diameter" of a channel is defined as twice the cross-sectional area of ​​the channel divided by the square root of the value pi, where the cross-sectional area is measured at a specified location within the channel.

[0095] As used herein, the term "fluid" encompasses all types of materials that exhibit fluid properties. One such property is the ability of the constituent particles to move relative to each other. For example, it can refer to a liquid such as water, or a gas such as air, nitrogen, or carbon dioxide. It should be noted that a fluid can simultaneously contain several different types and kinds of fluids, such as air, which is composed of several gases. Unless otherwise specified, for simplicity, a combination of different fluids is still referred to as a "fluid".

[0096] The term "free-flow" is defined as the theoretical flow relative to a specific point that occurs if an object (such as a component of a device) does not interact with the fluid. Therefore, it can also be called global free-flow. A component of a device can be an aircraft (such as an airplane or ship) or a different type of fluid-manipulated device (such as a wind turbine), or any part of such a component. Free-flow can include the contribution of the motion of a specific point in inertial space, such as the motion of an aircraft in inertial space. It can also include the contribution of the fluid motion in inertial space, such as wind or airflow. Different specific points can experience different free-flows. For example, a device can rotate, causing different points on the device to move at different velocities in inertial space and experience different free-flow velocities in a fluid that is theoretically stationary in inertial space.

[0097] The term "local free-flow" is defined as the theoretical flow relative to a specific device that occurs if only that specific device does not interact with the fluid. Local free-flow includes the contribution of the free-flow itself, as well as contributions due to other devices that interact with the fluid, such as those in the rest of the assembly. For example, the downwash generated by a horizontally fixed wing may affect the magnitude and direction of the local free-flow velocity relative to a horizontal stabilizer mounted downstream of the wing.

[0098] A “fluid manipulation device” or FMA is defined as a device that manipulates the properties of a fluid. For example, for a specific situation or boundary condition, an FMA can change the magnitude of the velocity of a fluid element relative to the magnitude of the free-flow velocity. In another instance, for a specific situation, an FMA can change the direction of the fluid velocity of a fluid element relative to the direction of the free-flow velocity. This effect on fluid flow can be intentional or involuntary. When at least some of the effects on the fluid are intentional, an FMA can be further classified as an “intentional fluid manipulation device” or IFMA. Intentional effects on fluid flow are limited to some IFMAs, such as in the case of an “intentional momentum carrying device” or IMCA as defined below. For other IFMAs, intentional effects on fluid flow may also occur in the far wake, such as in the case of an “intentional momentum release device” or IMSA. These definitions will be clarified in the following paragraphs.

[0099] Due to the intentional nature of momentum release, and because an IMSA can also be called a "thrust device" or TA, it is defined as any device configured to apply an intentional rate of change of momentum to a fluid during nominal operation. An example of a TA is a conventional propeller or helicopter main rotor. The wings of fixed-wing aircraft that provide lift during nominal constant-speed cruise can also be considered thrust devices. Many other possible types of TAs are available. For example, the rate of change of momentum can be applied to the fluid by an electromagnetic force via a TA. For example, a TA can be a Hall effect thruster or a magnetohydrodynamic (MHD) actuator. Voith-Schneider thrusters, gyroscopes, or similar devices are also examples of TAs.

[0100] In the above definition of a thrust device, the requirement to impose an intentional rate of change of momentum on the fluid can be described in several ways. For example, consider isolating the thrust device from other fluid manipulation devices in the device assembly. For example, consider isolating an airfoil from the rest of a fixed-wing aircraft. Or, consider isolating a helicopter main rotor from the rest of a conventional helicopter. In the theoretical case known as the "isolation case," the thrust device is considered isolated and is defined or characterized as follows: under nominal operating conditions, there is an intentional non-zero induced flow relative to the thrust device in the far wake.

[0101] In some cases, nominal operating conditions may involve the magnitude and direction of a free-flow velocity that is uniform in space and time. In other cases, operating conditions during constant-speed cruise can be described as nominal operating conditions. Under such nominal operating conditions, the far wake is located at an infinite distance from the thrust device. In other words, the thrust device has an intentional, non-negligible effect on the flow field at an infinite distance from the thrust device compared to the free-flow field.

[0102] The term "intentionality," as defined and used herein, refers to the requirement that the rate of change of momentum be useful or deliberate. For example, in the isolation described above, a useful rate of change of momentum can contribute to the average induced velocity of a fluid element in the far wake, where this velocity has a non-zero component in the direction opposite to the expected thrust or lift. For some thrust devices, the average induced velocity of a fluid element in the far wake has a considerable component in the direction opposite to the expected thrust or lift. The far wake-induced flow of a fixed-wing or helicopter main rotor associated with lift or thrust generation is considered intentional. The relevant rate of change of fluid momentum near the thrust device is also considered intentional. The intentional effect of a thrust device on the far wake differs from the unintentional, useless, or reactive effects on the fluid flow field in the far wake, which may be associated with, for example, form drag or pressure drag acting on certain elements of the thrust device. That is, these unintentional effects unnecessarily increase power consumption compared to the theoretical case where these effects are mathematically eliminated, all other things being equal.

[0103] The requirement to impose an intentional rate of change of momentum on a fluid can also be described in another way. For example, a thrust device can also be defined as any device that intentionally releases eddies within the simplified framework of Prandtl's lift line theory. Thus, a thrust device, or TA, or IMSA, can also be described as an "intentional eddy release device" or IVSA. It should be noted that the framework of lift line theory should only be considered as a reference or guide, as it relies on simplifying assumptions such as inviscid and incompressible flow. The intentionally or intentionally released eddies by the thrust device contribute to the lift or thrust acting on the thrust device by imposing a rate of change of momentum on the fluid. When considering the thrust device in the aforementioned isolated case under nominal operating conditions, the intentionally released eddies also exist at an infinite distance from the thrust device, where intentionally induced flow occurs. In other words, there exists a non-zero intentional far-wake induced velocity due to or generated by the thrust device. It should be noted that in some models, such as mathematical models that consider viscous drag or theoretical boundary layer effects that release eddies, the thrust device can also be regarded as releasing eddies unintentionally. Unintentional eddy release refers to any eddy that is not intentionally released, that is, any eddy that does not perform or contribute to a useful function such as generating lift or thrust.

[0104] Intentional momentum-carrying devices (IMCAs) are fluid maneuvers that, when considered in isolation, do not intentionally release momentum into the far wake. An example of an IMCA is a duct or a conventional tubular or cigar-shaped axisymmetric fuselage. The fuselage alters free-flow by intentionally deflecting the airflow around it, which also increases the magnitude of the flow velocity near the fuselage in isolation, where the fuselage is considered isolated from any other fluid maneuvering devices (such as wings) under nominal operating conditions (such as constant speed cruise). The intentional deflection of the flow described above is confined to the vicinity of the fuselage. Therefore, fluid elements near the fuselage experience an intentional local rate of momentum change. Ideally, this has no effect on fluid flow at an infinite distance from the fuselage. In other words, the fuselage has no intentional far wake effect on fluid flow. However, intentional rates of momentum change may exist near the fuselage, which, compared to free-flow, may also be associated with intentional momentum changes of fluid elements at an infinite distance from the fuselage in isolation. For example, such unintentional changes in fluid flow in the far wake can be caused by the shape drag effect.

[0105] Similarly, a conduit alters free-flow by intentionally changing the velocity magnitude near the conduit. For example, a conduit can be configured to reduce the velocity magnitude of the fluid element at the center of a circular conduit relative to free-flow under isolated conditions of nominal operating conditions. In this case, nominal operating conditions can refer to a constant and uniform free-flow velocity parallel to the conduit's central axis of symmetry. This intentional change is limited to the vicinity of the conduit and converges to a negligible value at an infinite distance from the conduit center. Therefore, the conduit has no intentional far-wake effect on the fluid flow; that is, there is no intentionally induced velocity in the far-wake of the fluid element due to the interaction between the conduit and the fluid. As mentioned earlier, there may be unintentional changes in the fluid flow in the far-wake due to traction drag or transient effects, as well as associated unintentional rates of momentum change of the fluid near the conduit.

[0106] IMCA can also be described within a simplified framework of lift line theory. IMCA can be viewed as having closed or bounded vorticity. Therefore, IMCA can also be considered as an "intentional vortex-carrying device" or IVCA. For example, the intentional effect of an axially symmetric circular duct on the fluid can be modeled as a circular vortex ring, or a two- or three-dimensional continuous vortex distribution, or a gradually decreasing discrete vortex ring. Note that under nominal operating conditions, no intentional vorticity is released into the fluid, where the magnitude of the vorticity is constant in time and uniform along the circumference of the vortex ring. Similarly, the intentional effect of the fuselage on fluid flow can be modeled as a three-dimensional continuous vortex distribution contained within the fuselage or located on the fuselage surface (i.e., the interface between the fuselage and the fluid).

[0107] The “induced power” of an IMSA is the rate of change of fluid energy associated with the intentional rate of change of the fluid’s momentum. Any other power consumption is included in the “zero-lift power” or “profile power.” It should be noted that in this context, the term “lift” also includes thrust. It should be noted that IMCA does not consume any induced power. Any power loss associated with pure IMCA is considered a profile power loss. An IMSA can consume induced power, in which case intentional work is done on the fluid through a fluid manipulation device. For example, the propeller of an aircraft or ship, or the fixed wing of a conventional fixed-wing aircraft, results in or is associated with induced power consumption. An IMSA can also recover induced power, in which case intentional work is done on the fluid manipulation device through the fluid. For example, the power generated by a wind turbine can be considered induced power.

[0108] In applying a rate of change of momentum to a fluid, a fluid manipulation device can alter the flow velocity relative to the local free-flow velocity. This velocity change is called "downwash" or "induced velocity." It should be noted that, for example, the induced velocity can be directed downstream or upstream, or perpendicular to the airflow. The induced velocity can be generated by an IMSA or an IMCA. In the latter case, the induced velocity is localized, i.e., confined to the vicinity of the IMCA. In these terms, an IMSA can also be characterized as a device that contributes an intentional induced velocity to the far wake in isolated conditions. It should be noted that when two IMSAs are considered simultaneously, the induced velocity contribution of one IMSA can be canceled out by the other.

[0109] Several apparatuses and methods used in the prior art will be discussed in the following paragraphs and in the context of Figures 1 and 2.

[0110] Figure 1 is a cross-sectional view of the prior art TA. It illustrates propeller 1, with the thrust of propeller 1 pointing towards the top of the figure, as shown by thrust vector 39. Under the operating conditions shown, there is a non-zero free flow from the top to the bottom of the figure, as indicated by arrow 40.

[0111] The dashed line schematically represents the approximate boundary 2 between the free-flow and the flow passing through the rotor disk. The line on the boundary can be described as a streamline, and the volume enclosed by the boundary can be described as a flow tube. It should be noted that the boundary shown in the figures is only an example of a specific operating condition. For other operating conditions or modes of operation of the depicted TA, such as hovering or extracting energy from free-flow (such as wind or water flow), the shape of the boundary can be quite different. In the free-flow far in front of the propeller, the flow is approximately equivalent to free-flow.

[0112] This state of the fluid is represented by station 3 in Figure 1. The fluid characteristics at the propeller are encapsulated by station 4. The flow in the far wake, or the free flow far downstream of the propeller, is represented by station 5. Because the propeller accelerates the flow, the area of ​​the flow tube decreases from station 3 to station 4 and from station 4 to station 5.

[0113] At station 5, the flow exhibits a greater velocity than free-flowing flows (such as those observed at station 3), where, within the framework of conventional simple momentum theory, it can be assumed that the flow pressure inside the flow tube has returned to the free-flow pressure. The greater velocity at station 5 indicates an increase in fluid momentum due to the propeller accelerating the flow and subjecting it to an equal and opposite force or thrust. The higher the velocity, the greater the kinetic energy in the fluid; in the aforementioned framework, kinetic energy represents the power required to provide thrust.

[0114] It should be noted that the simple momentum theory is used only as a framework to describe the basic principles of lift using TA, and the assumptions generally included in this theory are not intended to apply to the embodiments or limit the scope. For example, the distribution of the airflow downwash generally does not need to be constant across the cross-section of the flow tube. It should be noted that the flow tube radius drawn at each station is approximate and is intended only to indicate the general shape of the flow tube.

[0115] The cross-sectional view of the propeller shows the first propeller blade 6 and the second propeller blade 7. The trailing edge 9 of the first propeller blade 6 and the leading edge 10 of the second propeller blade 7 are also visible. A similar configuration is shown in all the figures containing the propeller.

[0116] Figure 2 is a cross-sectional view of another prior art TA. A ducted propeller is illustrated, with the thrust of propeller 11 pointing towards the top of the figure, as shown by thrust vector 41. Under the operating conditions shown, there is a non-zero free flow from the top to the bottom of the figure, as indicated by arrow 42. Additional thrust is generated by duct 16, which has a leading edge 17, a trailing edge 18, and a cross-section 19. Similar to Figure 1, there is a flow tube boundary 12 with a far upstream position 13, a position 14 at the rotor, and a far wake position 15. Duct 16 circumferentially surrounds propeller 11.

[0117] According to some embodiments, an apparatus and method are provided that can modify flow more effectively than methods employed in the prior art. This modification can be referenced to, but is not limited to, the flow velocity at a specified location in the flow, and can be applied to, but is not limited to, the generation of thrust.

[0118] The method includes: providing a thrust device assembly having an upstream thrust device configured to generate a desired force or thrust relative to free-flow in a first direction during nominal operation; and further providing a thrust device assembly having at least one downstream thrust device, wherein the downstream thrust device is at least partially disposed in at least a portion of a downstream flow tube of the upstream thrust device; and wherein the downstream thrust device is configured to generate thrust at the location of the downstream thrust device in the flow tube of the upstream thrust device, the thrust having at least one vector component in a direction parallel to the induced velocity vector of the upstream thrust device, wherein the thrust of the downstream thrust device satisfies the directional criterion in at least a portion of the overlapping region between the flow tubes of the upstream and downstream thrust devices. The thrust device assembly may include at least two thrust devices.

[0119] It should be noted that the flow tube can be bent by an external lifting device or thrust device. In some cases, the induced velocity vector of the upstream thrust device at the location of the downstream thrust device no longer needs to be aligned with the thrust received by the upstream thrust device. In some cases, it may also be unnecessary for it to be aligned with the induced velocity vector of the upstream thrust device at its location. The induced velocity vector of the downstream thrust device at its location is configured to have at least one component in the direction opposite to the induced velocity vector of the upstream thrust device at that location. Therefore, the thrust received by the downstream thrust device does not necessarily need to have a component in the direction opposite to the thrust of the upstream thrust device.

[0120] Alternatively, the method includes: providing a thrust device assembly having an upstream thrust device configured to apply a first momentum change rate relative to the free flow velocity vector in at least a predetermined direction; and further providing a thrust device assembly having at least one downstream thrust device, wherein the downstream thrust device is at least partially disposed in at least a portion of a downstream flow tube of the upstream thrust device; and wherein the downstream thrust device is configured to apply a second momentum change rate to fluid in the flow tube of the upstream thrust device, wherein for at least a portion of the overlapping region between the flow tubes of the upstream and downstream thrust devices, the direction of the second momentum change rate has at least one component in the opposite direction to the effect of the first momentum change rate on the fluid in the flow tube of the upstream thrust device.

[0121] Alternatively, the method includes: providing a thrust device assembly having an upstream thrust device configured to extract a desired amount of induced power from a fluid, and further providing a thrust device assembly having at least one downstream thrust device, wherein the downstream thrust device is at least partially disposed in at least a portion of a downstream flow tube of the upstream thrust device, and wherein the downstream thrust device is configured to deliver the desired amount of induced power to the fluid over at least a portion of the overlap region between the flow tubes of the upstream and downstream thrust devices.

[0122] Alternatively, the method includes: providing a thrust device assembly having an upstream thrust device configured to deliver a desired amount of induced power to a fluid, and further providing a thrust device assembly having at least one downstream thrust device, wherein the downstream thrust device is at least partially disposed in at least a portion of a downstream flow tube of the upstream thrust device, and wherein the downstream thrust device is configured to extract the desired amount of induced power from the fluid in at least a portion of the overlapping region between the flow tubes of the upstream and downstream thrust devices.

[0123] One advantage of such thrust device components is the alteration of flow velocity at specific points within the flow tube. For example, at a station between upstream and downstream thrust devices, the flow velocity can be artificially increased. Ideally, any work done by the upstream thrust device can be recovered by the downstream thrust device, minimizing energy loss in the process. Furthermore, any undesirable momentum changes exerted on the fluid by the upstream thrust device can be eliminated by the downstream thrust device. In other words, any undesirable thrust experienced by the upstream thrust device can be counteracted by the downstream thrust device. Therefore, some embodiments provide a method for altering flow that can be more efficient than methods employed in the prior art.

[0124] There are many possible embodiments of apparatus employing the above method. Figure 3 One embodiment is shown. The figure illustrates a thrust assembly comprising an upstream thrust unit 20 and a downstream thrust unit 21, whereby the upstream thrust unit 20 can be classified as a propeller, and the downstream thrust unit 21 can also be described as a propeller in this case. In other embodiments, the thrust units 20 or 21 can be of types other than the open rotor type shown. For example, the thrust unit can comprise several open rotors, or it can comprise at least one ducted fan or a pair of coaxial propellers rotating in opposite directions. Similar to Figure 1, there is a flow tube boundary 22 having a far upstream position 23, a position 24 at the upstream thrust unit 20, a position 25 between the upstream thrust unit 20 and the downstream thrust unit 21, a position 26 at the downstream thrust unit 21, and a far wake position 27. In this case, the downstream thrust unit 21 is disposed within the flow tube 22 of the upstream thrust unit 20.

[0125] In this example, the thrust assembly needs to provide a net thrust pointing vertically upwards towards the top of the figure, as shown by thrust vector 43. There is a free flow from the top to the bottom of the figure, as shown by arrow 45. The purpose of this embodiment is to reduce the induced power of the thrust assembly for a given amount of thrust compared to a baseline configuration. In this case, the baseline configuration is a single open rotor, such as the open rotor example shown in Figure 1, where the net thrust and actuator disk area are the same at stations 4 and 24.

[0126] According to some embodiments, this is achieved through the following Figure 3This is achieved using the IFMA configuration shown. The upstream thrust unit 20 is configured to provide thrust parallel to and greater than the required net thrust of the thrust unit assembly, where the net thrust is the sum of the thrust of the upstream thrust unit 20 and the thrust of the downstream thrust unit 21. The net thrust on the thrust unit assembly needs to equal the required thrust. Therefore, the thrust on the downstream thrust unit 21 is equal to the difference between the net thrust and the thrust of the upstream thrust unit 20. In this case, this results in the thrust on the downstream thrust unit 21 pointing vertically downwards towards the bottom of the figure, as shown by thrust vector 44, pointing in the opposite direction to the thrust on the upstream thrust unit 20. In other words, the downstream thrust unit 21 is configured to extract any momentum applied to the fluid by the upstream thrust unit that would violate, and in this case exceed, the required net thrust constraint on the thrust unit assembly. The downstream thrust unit 21 is also configured to extract power from the fluid. To improve induced power consumption compared to the baseline, a sufficient portion or all of the extracted induced energy needs to be reversibly recovered or directly transferred to the upstream thrust unit 20.

[0127] Energy can be reversibly recovered by either storing it reversibly within the thrust assembly or transferring it reversibly to another device that interacts with the thrust assembly. For example, a downstream thrust unit can drive a generator G, which may include an electric motor configured to convert a portion of mechanical energy into electrical energy. A portion of the electrical energy can be reversibly stored in batteries, capacitors, or other energy storage devices. Batteries can be located within the thrust assembly or on external devices attached to the thrust assembly (such as the rest of the aircraft). Energy can also be mechanically extracted and stored in the form of a flywheel.

[0128] Energy can be directly transferred to the upstream thrust device 20 in several ways. For example, if energy is extracted from the downstream thrust device 21 via a generator G, electrical energy can be transferred via electrical conductors or wires to the electric motor M driving the upstream thrust device 20. Alternatively, the power extracted by the downstream thrust device can be mechanically transferred in the form of a drive shaft that rigidly connects the upstream thrust device 20 and the downstream thrust device 21. In some embodiments, the mechanical energy transfer device does not need to form a rigid connection, but instead includes adjustable linkages, gears, and other mechanisms such as clutches.

[0129] There are many other known methods in the art for recovering and storing mechanical energy from downstream thrust device 21 or for transferring mechanical energy to upstream thrust device 20.

[0130] The above embodiment results in an induced power lower than the baseline induced power. For a given maximum actuator disk area and a given net thrust at stations 4 and 24, the induced power decreases as the thrust of the upstream thrust device 20 increases. It should be noted that the thrust of the upstream thrust device 20 needs to be greater than the required net thrust in order to achieve a reduction in induced power compared to the baseline in this example.

[0131] Some embodiments provide improvements to the ducted thrust device shown in Figure 2. This duct offers several advantages, such as reduced propeller tip losses, allowing the duct to operate with lower induced power at the same thrust as an open rotor. However, the duct also has several disadvantages. It can increase the weight of the TA, as well as the wetting area and associated drag. The effectiveness of the duct is also limited by the risk of flow separation in the diffuser. Furthermore, due to complexity and weight, altering the shape of the duct to achieve efficiency gains at different flow rates is generally impractical.

[0132] Some embodiments are less affected by some of these disadvantages. For some ductless embodiments, the thrust unit can benefit from the duct without equivalent losses in weight and wetting area. To avoid flow separation, a duct would require a large diffuser, which may be impractical due to weight and size constraints. Ductless embodiments are less sensitive to stall constraints, which will allow some embodiments to achieve better performance than ducted rotors. The thrust unit can also be reconfigured with less complexity than a ducted rotor. For example, an open rotor type thrust unit can be reconfigured by changing the overall pitch of the propeller blades, and the rotational speed can be easily controlled. This allows the thrust unit to operate more efficiently with less complexity under different operating conditions, such as hovering or level cruise.

[0133] It should be noted that, Figure 3 In this configuration, the upstream thrust device 20 provides the required thrust for a particular thrust device assembly and additional thrust offset by the downstream thrust device 21. In some embodiments, it may be desirable to physically separate the thrust devices that offset each other's net thrust contribution to the thrust device assembly from the rest of the thrust device assembly.

[0134] Figure 4This situation is illustrated. The figure shows an auxiliary thrust assembly comprising an upstream thruster 28 and a downstream thruster 30, where the upstream thruster 28 can be classified as a propeller, and the downstream thruster 30 can also be described as a propeller in this case. The figure also shows an intermediate thruster 29, which is also an open rotor type. There is a free flow pointing vertically downwards from the top of the figure to the bottom, as indicated by arrow 49. Similar to Figure 1, there is a flow tube boundary 31 with a far upstream position 32, a position 33 at the upstream thruster 28, a position 34 between the upstream thruster 28 and the intermediate thruster 29, a position 35 at the intermediate thruster 29, a position 36 between the intermediate thruster 29 and the downstream thruster 30, a position 37 at the downstream thruster 30, and a far wake position 38. In this case, the intermediate thrust device 29 and the downstream thrust device 30 are disposed in the flow tube 31 of the upstream thrust device 28.

[0135] In this example, the intermediate thrust unit 29 provides thrust equal to the required net thrust of the total thrust assembly, as shown by thrust vector 47, where the thrust assembly includes the upstream thrust unit 28, the intermediate thrust unit 29, and the downstream thrust unit 30. Therefore, the auxiliary thrust assembly does not need to provide net thrust. Figure 3 As shown, compared to the baseline configuration, the objective of this embodiment in this instance is to reduce the induced power of the entire thrust device assembly for a given thrust. In this case, the baseline configuration is also a single open rotor, such as the open rotor example shown in Figure 1, where the net thrust and actuator disk area are the same at positions 4 and 33.

[0136] According to some embodiments, this is achieved through the following Figure 4 This is achieved in the illustrated embodiment. The upstream thrust device 28 is configured to provide thrust that is parallel to and greater than the required net thrust of the total thrust device assembly, where the net thrust is the thrust of the upstream thrust device 28 plus the thrust of the intermediate thrust device 29 plus the thrust of the downstream thrust device 30. Therefore, the thrust of the upstream thrust device 28 points towards the top of the page, as shown by thrust vector 46. In this case, the thrust on the downstream thrust device 30 is equal to and opposite to the thrust of the upstream device 28, as shown by thrust vector 48. In other words, the downstream thrust device 30 is configured to extract any momentum applied to the fluid by the upstream thrust device that would violate, and in this case exceed, the required net thrust constraint on the total thrust device assembly. The downstream thrust device 30 is also configured to... Figure 3 The downstream thrust device 21 in the process describes the way power is extracted from the fluid.

[0137] It should be noted that, for the overall purpose, the upstream and downstream thrust devices do not need to operate individually at minimum induced power, as long as the total induced power is minimized (if this is the objective). For example, if the objective is to maintain a constant airflow downwash across the cross-section of the far-flow tube at station 38, the airflow downwash from the upstream thrust device 28 or the intermediate thrust device 29 does not need to be uniform, as long as any non-uniformity is eliminated by the downstream thrust device.

[0138] It should be noted that the principles applicable to coaxial propellers also apply to some embodiments. For example, the actuator disk area at station 35 of the intermediate thrust unit 29 can be as large as the actuator disk area of ​​the upstream thrust unit 28 at station 33. Therefore, a portion of the intermediate thrust unit interacts with the free flow. This area can be used to further apply a rate of change of momentum to the fluid in the direction of the desired thrust of the total thrust unit assembly. This allows the thrust unit assembly to further reduce the induced power compared to the baseline. Similarly, the actuator disk area of ​​the downstream thrust unit can be increased, such as... Figure 4 30 or Figure 3 21. The concept of interaction with bypass fluid flow is well known in the art. Furthermore, as is known in the prior art, the direction of rotation of the propeller in the flow tube can be selected to minimize vortices in the far wake.

[0139] Other embodiments will be described in the following paragraphs.

[0140] For generality, it is beneficial to consider embodiments individually. In one embodiment, the purpose of the device is to increase the local velocity relative to free flow at a specific point in the flow. This can be achieved by a thrust device assembly having an upstream thrust device configured to apply a rate of change of momentum downstream, thereby generating a downstream induced velocity vector. The upstream thrust device is located upstream of the specific point in the flow and is thrust in the upstream direction, doing work on the fluid, resulting in induced power consumption. The thrust device assembly may further include a downstream thrust device configured to apply a rate of change of momentum upstream, thereby generating an upstream induced velocity vector. The downstream device is located in the flow tube of the upstream thrust device. The downstream thrust device is located downstream of the specific point in the flow and is thrust in the downstream direction, recovering power from the fluid. Ideally, all induced power applied to the fluid by the upstream device is recovered by the downstream device, so that no net induced power is lost to the fluid. In the idealized case requiring zero net thrust of the thrust device assembly, the thrusts on the upstream and downstream thrust devices further cancel each other out. Provided the upstream and downstream thrust assembly are positioned far enough apart to allow for flow acceleration, a specific point between them can experience a desired increase in local velocity. This is due to the induced flow or downwash from the upstream thrust assembly and the downwash from the downstream thrust assembly. This downwash can then be further recovered downstream of the specific point by the downstream thrust assembly, so that, ideally, there is no downwash in the far wake of the flow tube.

[0141] In another embodiment, the purpose of the device is to reduce the local velocity at a specific point in the flow. According to some embodiments, this can be achieved by reversing the actions of the upstream and downstream thrust devices, compared to the examples described above. Thus, the upstream thrust device can be configured to apply a rate of change of momentum upstream, thereby generating an upstream induced velocity vector. Similarly, the downstream thrust device can be configured to apply a rate of change of momentum downstream, thereby generating a downstream induced velocity vector. Ideally, all induced power recovered by the upstream device is consumed by the downstream device, so that the thrust devices do not extract net induced power from the fluid.

[0142] It should be noted that the upstream thrust device only needs to meet local velocity requirements at specific points. Compared to free flow, different points in the flow tube containing the actuator disk area of ​​the upstream thrust device may require different increases or decreases in local velocity. Local velocity requirements can be viewed as requirements for the airflow downwash of the thrust device assembly at specific points or point sets within the flow tube, or near the flow tube. These requirements can be met by varying the thrust distribution over the actuator disk areas of the upstream and downstream thrust devices. Considering these flow constraints at specific points, additional objectives may exist, such as minimizing induced power, which can be translated into additional requirements for zero or uniform downwash in the far wake. This objective could also be minimizing the total power consumed under these operating conditions.

[0143] Consider the operating conditions of the thrust assembly, aiming to maximize the power extracted from the fluid for a given maximum actuator disk area and freeflow velocity, assuming that structural constraints are always satisfied. A baseline configuration consisting of open rotors (such as wind turbines) can be considered. According to some embodiments, the thrust assembly may include an upstream thrust unit and a downstream thrust unit. In this example, the downstream thrust unit is disposed in the slipstream of the upstream thrust unit. There is a non-zero freeflow. The upstream thrust unit is configured to do work on the freeflow by applying a rate of change of momentum to the flow in the downstream direction. Through interaction with the fluid, the upstream thrust unit is thus subjected to an upstream force. The downstream thrust unit is configured to extract power from the flow in the flow tube of the upstream thrust unit. In other words, the fluid does work on the downstream thrust unit and is subjected to an upstream rate of change of momentum, causing the downstream thrust unit to be subjected to a downstream force. Therefore, performance improvements can be achieved compared to the baseline open rotor configuration. For example, a wind turbine may include two open rotors, one located upstream of the mast and the other downstream of the mast. The rotors can operate as described above. The power consumed by the upstream rotor can be supplied by an external power source or the downstream rotor. For example, in Figure 3 As mentioned in the description, power can be mechanically transferred between the upstream and downstream thrust units, for example, via a direct connection to the shaft or via an adjustable transmission including gear trains and clutches. Power can also be transferred electrically, in which the downstream rotor drives a generator, and the generator's electrical energy is transferred to the electric motor driving the upstream rotor. It should be noted that other configurations are also possible, and the principle also applies to hydraulic turbines or other thrust units or operating conditions.

[0144] In some embodiments or operating conditions, it may be desirable to reduce, rather than increase, the local flow velocity at the actuator disk of the downstream rotor. For example, in the case of a wind turbine, the free-flow velocity may exceed the permissible peak free-flow velocity of the downstream rotor under certain operating conditions. It should be noted that due to the different dimensions and nominal operating loads of the upstream and downstream rotors, the peak free-flow velocity of the upstream rotor, determined by structural constraints, may be greater than that of the downstream rotor. They may also differ in design. In this case, the thrust on the upstream rotor can be reversed to extract power from the flow and reduce the velocity at the downstream rotor to a nominal level. This prevents the thrust on the downstream rotor from exceeding design limits. Therefore, the upstream thrust device can be used to modify the flow field, thereby optimizing the performance of the entire thrust device assembly. It should be noted that other methods known in the art are also applicable to such situations. In the case of a single open rotor, operating conditions such as rotational speed and propeller pitch can be adjusted. However, the effectiveness of these methods is limited by the range of free-flow velocities, and some embodiments can extend these limitations. The principles described in the context also apply to other operating conditions and situations.

[0145] In the following paragraphs and in the context of Figure 5, some of the devices and methods used in the prior art will be discussed.

[0146] "Boundary device" includes any incremental surface or volume of a fluid manipulation device that directly applies force or torque to a fluid element, or vice versa. Examples of boundary devices are the wetted surfaces of an aircraft fuselage, the wetted surfaces of a ship's hull, the skin of an aircraft wing, the surface of a flat plate, or the outer surface of a car.

[0147] Figure 5 shows a cross-sectional view of a boundary device 61 moving relative to the surrounding fluid. The boundary device 61 has a leading edge point 64 and a trailing edge point 65. The leading and trailing edge points can also be edges, such as the leading or trailing edge of an airfoil. In this particular embodiment, for simplicity, the boundary device is a rigid body that can be described as a thin shell, having a closed outer surface 62 and an inner surface 63. In this embodiment, the boundary device 61 has a shape of revolution, i.e., it is axisymmetric about an axis passing through the leading edge point 64 and the trailing edge point 65.

[0148] The "Boundary Device Frame" or "BAF" can be defined as follows: The origin is located at the geometric centroid of the volume enclosed by the outer surface 62 of the boundary device 61. The x-axis coincides with the line connecting the leading edge point 64 and the trailing edge point 65, and points towards the leading edge point 64. Unless otherwise specified, the z-axis points perpendicularly to the page of the accompanying drawing.

[0149] Three velocity distribution diagrams 67-69 are shown. Each arrow in the velocity distribution diagram indicates the velocity vector of the incremental fluid element relative to the boundary device, with the incremental fluid element located at the base of the arrow. The line connecting the tips of the arrows in velocity distribution diagram 67 describes the continuous velocity distribution.

[0150] Boundary device 61 moves relative to the surrounding fluid. The free-flow velocity is spatially uniform and temporally constant. In Figure 5, the free-flow fluid relative to boundary device 61 is guided parallel to the x-axis of the BAF and in its opposite direction, i.e., from the top to the bottom of the figure. Upstream of the distal end of boundary device 61, the velocity of the incremental fluid element is approximately equal to the free-flow velocity. Therefore, the velocity distribution map 67 is uniform, with both magnitude and direction equal to the free-flow velocity.

[0151] Velocity distribution diagram 68 illustrates the velocity distribution near the boundary device 61. In this embodiment, a no-slip condition exists on the surface of the boundary device 61. In other embodiments, non-zero slip velocity may exist along the outer surface 62. Due to viscous effects, the velocity gradient generated in the y-axis direction of the BAF causes shear stress acting on the boundary device 61, which in turn causes viscous traction drag. The viscous traction drag is parallel to the x-axis of the BAF and points in the negative x-direction.

[0152] Streamline 66 describes the approximate thickness of the boundary layer associated with boundary device 61. Since boundary device 61 is cylindrically symmetrical, streamline 66 can also be referred to as flow tube 66.

[0153] Velocity distribution diagram 69 illustrates the velocity distribution in the far wake of boundary device 61. The decreasing velocity magnitude within flow tube 66 in velocity distribution diagram 69 indicates the momentum deficit in the far wake caused by the viscous drag acting on boundary device 61.

[0154] According to some embodiments, the flow field around the boundary device is altered by a fluid flow manipulation device in such a way that, for at least one operating condition, the viscous resistance on the combined device is lower than that of the baseline boundary device.

[0155] The baseline boundary device does not need to have the same shape as the boundary device in the combined device. The baseline boundary device is a conventional device used in the prior art, such as the boundary device 61 shown in Figure 5. For example, the baseline boundary device can have the shape of a conventional tubular aircraft fuselage.

[0156] Slip velocity is the velocity of a fluid at and relative to the surface of a boundary device. In viscous fluids, the slip velocity is typically smaller in magnitude than the slip velocity calculated for the theoretical case of an inviscid fluid. The difference between these two velocities is called the "velocity deficit." Due to viscous effects, the velocity deficit at the boundary device surface propagates through the fluid in a direction perpendicular to the local free-flow velocity. As a result, a non-negligible fluid volume is affected by the velocity deficit. The fluid flow region affected by this velocity deficit is called the boundary layer. The thickness of this region is called the boundary layer thickness. All else being equal, the boundary layer thickness can be defined as the region where the velocity deficit is greater than 1% of the magnitude of the velocity calculated for the theoretical case of an inviscid fluid. The velocity deficit translates into a momentum deficit, which causes viscous shear stress and viscous drag acting on the boundary device.

[0157] According to some embodiments, compared to a case where the influence of the fluid flow manipulation device on the fluid flow is mathematically eliminated, the local free-flow velocity is reduced for at least a portion of the wetted area of ​​the combined device. The fluid flow manipulation device is configured such that the increase in power consumption of the combined device due to the additional wetted area of ​​the fluid flow manipulation device compared to the baseline boundary device is less than the decrease in power consumption of the boundary device due to the traction resistance acting on the boundary device compared to the baseline boundary device. A portion of the reduction in power consumption of the boundary device can be caused by the reduction in the local free-flow velocity of the boundary device. Alternatively or simultaneously, the fluid manipulation device can be configured to favor laminar flow rather than turbulent flow in at least a portion of the boundary layer of the boundary device. Another portion of the reduction in power consumption can be caused by a change in the shape of the boundary device compared to the baseline boundary device. The fluid flow manipulation device can manipulate the flow in such a way that the wetted area of ​​the boundary device can be reduced without increasing pressure drag due to the separation of a portion of the flow. For a given volume to be surrounded by the boundary device, the shape of the boundary device with the smallest wetted area is a sphere. However, a sphere causes significant pressure drag due to stall flow downstream of it. Even without stall, a sphere exhibits significant viscous drag due to its large mean square local free-flow velocity over its wetted area and the boundary layer effect. Besides reasons such as ease of manufacture, most fuselages have an elongated shape resembling a tube or teardrop for these reasons. Fluid manipulation devices can alter the flow, reducing the wetted area of ​​the boundary device and simultaneously decreasing the mean square local free-flow velocity compared to the baseline boundary device.

[0158] Flow field alterations can take several forms, and each form of alteration can be performed through several different embodiments of the fluid manipulation device.

[0159] Figure 7An IFMA configuration is depicted, comprising a boundary device 95 that moves relative to the surrounding fluid. The boundary device 95 has a leading edge point 98 and a trailing edge point 99. The leading and trailing edge points can also be edges, such as the leading or trailing edge of a wing or airfoil. In the case of a wing, the leading and trailing edges can be considered as a leading and trailing stagnation line under specific flow conditions. In this embodiment, the boundary device is a rigid body that can be described as a thin shell, having a closed outer surface 96 and an inner surface 97. In this embodiment, the boundary device 95 has a rotational shape, i.e., it is axially symmetrical about an axis passing through the leading edge point 98 and the trailing edge point 99.

[0160] Boundary device 95 can be the hull of a ship or the fuselage of an aircraft. In other embodiments, boundary device 95 can have different geometries. For example, the shape of the boundary device can be similar to that of boundary device 61 shown in FIG. 5. Suitable geometries can be found for any given application. Boundary devices can be manufactured using a variety of existing methods and materials.

[0161] The "Boundary Device Frame" or "BAF" can be defined as follows. The origin is located at the geometric centroid of the volume enclosed by the outer surface 96 of the boundary device 95. The x-axis coincides with the line connecting the leading edge point 98 and the trailing edge point 99, and points towards the leading edge point 98. Unless otherwise specified, the z-axis points perpendicularly to the page of the accompanying drawing.

[0162] Three velocity distribution diagrams 101-103 are shown. Each arrow in the velocity distribution diagram indicates the velocity vector of the incremental fluid element relative to the boundary device, where the incremental fluid element is located at the base of the arrow at the time point in time at which the velocity is measured relative to the boundary device. The line connecting the tips of the arrows in the velocity distribution diagram describes a continuous velocity distribution.

[0163] The boundary device 95 moves relative to the surrounding fluid. In the simplified case illustrated, the free flow velocity is spatially uniform and temporally constant. Figure 7 In the diagram, the free-flowing fluid relative to the boundary device 95 is guided parallel to the x-axis of the BAF and in its opposite direction, i.e., from the top to the bottom of the diagram. Upstream of the distal end of the boundary device 95, the velocity of the incremental fluid element is approximately equal to the free-flowing velocity. Therefore, the velocities in velocity distribution diagram 101 are spatially uniform and temporally constant, with magnitude and direction equal to the free-flowing velocity relative to the boundary device.

[0164] Velocity distribution diagram 102 illustrates the velocity distribution near the boundary device 95. In this embodiment, a no-slip condition exists on the outer surface 96 of the boundary device 95. In other embodiments, there may be non-zero slip velocity along the outer surface 96.

[0165] Streamline 100 describes the boundary of the flow tube, which has a circular cross-section when viewed along the x-direction. Figure 7 The dashed line in the diagram schematically represents the approximate boundary 100 between the free flow and the flow passing through the rotor disk of the upstream IMSA 104. The lines on the boundary can be described as streamlines, and the volume enclosed by the boundary can be described as a flow tube. It should be noted that... Figure 7 The boundary shown is only an example of a specific operating condition. For other operating conditions or modes of operation of the IMSA depicted, the shape of the boundary can be quite different.

[0166] Velocity distribution diagram 103 depicts the velocity distribution in the far wake of boundary device 95. In a simplified ideal case, velocity distribution diagram 103 is essentially equal to velocity distribution diagram 101, as shown below. Figure 7 As shown. In other embodiments, this is not necessarily the case.

[0167] According to some embodiments, the boundary device (such as boundary device 95) is provided with intentional fluid manipulation means. Figure 7 In the illustrated IFMA configuration, the intentional fluid manipulation device can be described as an IMSA assembly comprising an upstream IMSA 104 and a downstream IMSA 110. The upstream IMSA 104 can be classified as a propeller, and the downstream IMSA 110 can also be described as a propeller in this case. In this configuration, the downstream IMSA 110 is disposed within the flow tube 100 of the upstream IMSA 104. In other embodiments, this is not necessary. For example, in other embodiments, the downstream IMSA 110 may extend beyond the flow tube 100 of the upstream IMSA 104. Such a configuration is useful when the downstream IMSA 110 also contributes positively to the net thrust of the IMSA assembly.

[0168] A cross-sectional view of a propeller (such as propeller 104 or upstream IMSA 104) shows a first propeller blade 105 and a second propeller blade 106. The leading edge 109 of the first propeller blade 105 and the trailing edge 108 of the second propeller blade 106 are also visible. A similar configuration is shown in all the figures containing propellers. The propeller blades are structurally supported by a rotor hub 107.

[0169] The downstream IMSA 110 is configured in a similar manner to the upstream IMSA 104, and therefore will not be described in detail. The upstream IMSA 104 and the downstream IMSA 110 are rigidly connected to the boundary device 95 via a connecting device. For clarity, in Figure 7 The device is not shown in the image.

[0170] In other embodiments, the type of IMSA 104 or 110 may differ from the depicted open rotor type. For example, the IMSA may include several open rotors, or may contain at least one ducted fan or a pair of counter-rotating coaxial propellers. The IMSA may also be a gyroscope or a different type of IMSA.

[0171] According to some embodiments, the flow field near the boundary device is intentionally altered by a fluid manipulation device in such a way that the average spatial gradient of the flow velocity in the direction perpendicular to the surface of the boundary device is artificially and intentionally reduced. Shear stress is proportional to the velocity gradient of a Newtonian fluid. Therefore, the viscous shear stress acting on the boundary device is lower compared to prior art embodiments. In some embodiments, the reduction in viscous power consumed by the boundary device is greater than the increase in viscous power consumption by the intentional fluid manipulation device compared to a representative boundary device of the prior art. Therefore, for a certain range of operating conditions, a net reduction in viscous power consumption can be achieved through some embodiments. The optimal configuration of the intentional fluid manipulation device and the boundary device depends on the application and constraints and can be discovered using various methods. For example, many such methods are well known in computational fluid dynamics.

[0172] exist Figure 7 In the illustrated embodiment, the fluid manipulation device comprises an upstream IMSA 104 and a downstream IMSA 110. This fluid manipulation device is referred to as an "IMSA assembly". The IMSA assembly reduces the average spatial gradient of the flow velocity at the surface of the boundary device 95 and in the direction perpendicular to the surface of the boundary device 95 by intentionally and artificially altering the spatial distribution of the flow velocity near the surface of the boundary device 95.

[0173] In some embodiments, this change includes reducing the flow velocity magnitude at the outer surface 96 of the boundary device 95 in the case of full slip. The “full slip case” is a theoretical case where there is no boundary layer effect or no slip condition on a particular surface. In this theoretical case, the boundary layer effect or viscous drag effect of the outer surface 96 on the fluid flow has been mathematically eliminated for the particular surface. The aforementioned velocity reduction occurs relative to locally free-flowing fluid flow, i.e., flow around the boundary device 95 without the IMSA components; in this case, the full slip case is also calculated. The case assuming that the IMSA components have no effect on the fluid flow is called the “reference case.” It should be noted that the nature of the reference case is determined by the case it is compared to. For example, it should be clear from the context whether a particular reference case should consider conditions with or without slip. The velocity reduction is a result of the combined induced velocities of the upstream IMSA 104 and downstream IMSA 110 at the surface of the boundary device 95 pointing in the positive x-direction of the BAF. Compared to the reference case, this reduction in the flow velocity magnitude at the outer surface 96 of the boundary device 95 in the case of full slip can reduce the Reynolds number at the outer surface 96. In the no-slip condition, a decrease in the Reynolds number can increase the boundary layer thickness and reduce the average spatial gradient of the flow velocity at the outer surface 96 in the direction perpendicular to the outer surface 96. Therefore, the average viscous shear stress and viscous drag loss at the outer surface 96 can be reduced.

[0174] In some embodiments, although the velocity at the outer surface 96 is reduced in magnitude, it can still have a non-zero component in the negative x direction under the condition of full slip at the outer surface 96. In other words, compared with the reference case with the full slip condition described above, the overall direction of the velocity of the fluid element at the outer surface 96 can remain substantially unchanged under the condition of full slip.

[0175] In the depicted example, the magnitude of the fluid flow at the outer surface 96 of the boundary device 95 has been artificially reduced to essentially zero in the case of full slip. When the magnitude of the fluid velocity at a given surface is zero in the case of full slip, the no-slip case would be equivalent to the full-slip case, all other things being equal. In this case, the viscous resistance on the outer surface 96 would be zero. In this idealized simplification, the flow tube 100 can be considered as an artificial boundary layer of the boundary device 95. It should be noted that this configuration may not be optimal, i.e., minimizing the total viscous resistance, when the viscous resistance effect of the IMSA components is also considered.

[0176] As shown in velocity distribution diagram 102, at the indicated location, the gradient of the fluid velocity magnitude in the direction perpendicular to the outer surface 96 is also essentially zero. In some embodiments, this gradient may be greater than zero on an average value calculated over the entire outer surface 96. However, this average gradient can be smaller compared to a reference case with no-slip conditions.

[0177] In other embodiments, the fluid flow within the flow tube 100 near the boundary device 95 can have different spatial variations or distributions. For example, flow recirculation can exist. In other words, for all or part of the outer surface 96, the fluid velocity on the outer surface 96 adjacent to the boundary device 95 can have a non-zero component in the positive x-direction under full slip conditions. In this case, a stagnant vortex ring (i.e., a ring of circulating flow) will surround all or part of the boundary device 95. Due to symmetry, this vortex ring will have a central axis aligned and coincident with the x-direction of the BAF and will lie in a plane parallel to the yz-plane of the BAF. Such a vortex ring will be held in place by the MSA assembly and re-excited by the surrounding flow.

[0178] In some embodiments, the spatial distribution of flow velocity within the flow tube 100 near the boundary device 95 is also intentionally altered. Figure 7 In the illustrated embodiment, the spatial distribution of the induced velocity is configured to produce a substantially linear change in the magnitude of the fluid velocity within the flow tube 100. As shown, the magnitude of the fluid velocity within the flow tube 100 increases substantially linearly in the positive y-direction. In other embodiments, the magnitude of the velocity within the flow tube 100 increases at an incremental rate in the positive y-direction. This configuration can help artificially maintain a low Reynolds number for the boundary layer of the outer surface 96, even if the boundary layer thickness increases in the flow direction (i.e., the negative x-direction of the BAF). The gradual gradient of the velocity magnitude can also minimize frictional heating and turbulence effects within the flow tube 100, thereby reducing drag losses or net power consumption associated with the boundary device 95. In simulations where the flow tube 100 is considered an artificial boundary layer of the boundary device 95, a gradual gradient of the velocity magnitude may be desirable to ensure that the artificial boundary layer is substantially laminar and remains laminar. Furthermore, the gradual increase in velocity magnitude within the flow tube 100 will ensure the existence of a minimum momentum transfer from the surrounding flow to the flow tube 100, which will result in a momentum deficit in the flow around the flow tube 100 in the far wake (i.e., in velocity distribution diagram 103) and contribute to the viscous power dissipation associated with the boundary device 95.

[0179] The optimal spatial variation of the fluid velocity within flow tube 100 can be found using existing methods, and it does not have to be linear. For example, among other criteria, it may be desirable to reduce the rate at which the total vorticity released into the fluid from upstream IMSA 104 is reduced.

[0180] The optimal magnitude and direction of the fluid flow at the outer surface 96 under full slip conditions, as well as the magnitude and characteristics of the velocity gradient at the outer surface 96, can be optimized using existing methods for a given flow condition or application. The same methods can also be used to optimize the optimal distribution of fluid velocity within the flow tube 100. The aim of such optimization can be to minimize the total power consumption of the boundary devices and IMSA components.

[0181] The aforementioned velocity distribution near the boundary device 95 is illustrated by a snapshot provided in velocity distribution diagram 102. This velocity distribution differs significantly from the velocity distribution for reference cases with or without slippage. According to some embodiments, this difference is provided by an intentional fluid manipulation device. Figure 7 In the illustrated embodiment, the fluid manipulation device is implemented by an IMSA component. The IMSA component manipulates the fluid by applying a specific spatially induced flow distribution. This induced flow can be viewed as superimposed on the fluid flow under a fully slip condition to the fluid flow under a reference condition. In other words, the desired velocity distribution can be generated by calculating the induced flow distribution required to change the flow from the reference condition to the desired velocity distribution and configuring the IMSA component in a manner that achieves the desired induced flow distribution. The viscous drag range associated with the outer surface 96, i.e., the influence range of the boundary layer and the no-slip condition, is determined or defined by this superimposed flow, i.e., the superposition of the induced flow and the flow in the reference condition. This viscous effect can also be viewed as superimposed on the aforementioned superimposed flow. As described in the following paragraphs, there are several ways to describe the generation or creation of the aforementioned induced velocity distribution of the IMSA component.

[0182] The induced velocity distribution near the boundary device 95 can be considered as being generated by the rate of momentum change of the fluid elements due to their interaction with the upstream IMSA 104. In some embodiments, some fluid elements experience a negative average rate of momentum change during their interaction with the upstream IMSA 104. This rate of momentum change can result in a net reduction in the momentum of the fluid elements near the outer surface 96 of the boundary device 95 after the fluid elements have interacted with the upstream IMSA 104. This reduction occurs relative to the reference case under full slip conditions, i.e., relative to the case where the IMSA components do not interact with the fluid. In other words, in some embodiments, the upstream IMSA 104 is configured to reduce the average momentum of at least a portion of the fluid flow in the far wake of the upstream IMSA 104 under the aforementioned isolation conditions.

[0183] In some embodiments, the reduction in the average momentum of the fluid flow in the far wake occurs at least for streamlines interacting with the outer surface 96 of the boundary device 95 or for streamlines passing near the outer surface 96. This reduction in the momentum of the fluid flow results in a far wake-induced velocity, which has a non-zero component in the upstream direction, as defined by the free flow in the isolated case, compared to the free flow in the isolated case. Since the outer surface 96 of the boundary device 95 is located downstream of the upstream IMSA 104, the flow at or near the outer surface 96 of the boundary device 95 is also subject to an upstream-induced velocity. As described above, the magnitude and spatial distribution of the upstream-induced velocity at or near the outer surface 96 of the boundary device 95 can be configured to reduce the magnitude of the free flow in the fully slipped reference case compared to the fully slipped reference case, and thus reduce the average drag of the boundary device 95 or the average power dissipation associated with the interaction between the boundary device 95 and the fluid.

[0184] Within the simplified framework of the lift line theory, the aforementioned induced velocity distribution can also be generated by free vortices released into the wake by the propeller blades of the upstream IMSA 104. This is similar to the vortex release of a helicopter rotor, a conventional propeller blade, or a wind turbine blade. It should be noted that in some embodiments, vortices released by the downstream IMSA 110 also contribute to the induced velocity near the boundary device 95 (such as at the location in velocity distribution diagram 102).

[0185] The aforementioned induced velocity distribution can also be generated by an appropriate lift or thrust distribution along the propeller blades of the upstream IMSA 104. Since the induced velocity of the upstream IMSA 104 points upstream for at least a portion of the upstream IMSA 104 (i.e., the positive x-direction of the BAF), the operation of the upstream IMSA 104 is analogous to that of a wind turbine. In other words, corresponding to the induced velocity distribution in the wake of the upstream IMSA 104, the thrust experienced by at least a portion of the blades of the upstream IMSA 104 (e.g., the first propeller blade 105) has a non-zero component in the negative x-direction of the BAF, as shown by thrust vector 127.

[0186] At least a portion of the upstream IMSA 104 is configured to extract useful power from the fluid. This power can be extracted in various ways. For example, a generator can be rigidly connected to a drive shaft, which in turn is rigidly connected to the propeller blades of the upstream IMSA 104. Figure 7In the illustrated embodiment, the drive shaft may be parallel to the rotation axis of the propeller blades of the upstream IMSA 104 and parallel to the x-axis of the BAF. In some embodiments, when the upstream IMSA 104 is configured as a conventional propeller, the aforementioned drive shaft is considered as the rotor hub or the propeller shaft of a conventional propeller. Since the electric motor is directly connected to the drive shaft, and the drive shaft is directly connected to the propeller blades, this configuration can also be described as a direct drive configuration.

[0187] In some embodiments, a transmission or gear train may also be present between the generator and the drive shaft. In some embodiments, a clutch may also be present between the propeller and the transmission. In some embodiments, the transmission may be reconfigured. In other words, the gear ratio may be changed, or the gears may be changed. In some embodiments, a mechanical disc brake attached to the drive shaft may also be present, wherein the brake is configured to stop or prevent rotation of the drive shaft. The electricity generated by the generator due to the rotation of the drive shaft may be stored in an energy storage device. For example, such an energy storage device may be a battery or a capacitor. The energy storage device may also include mechanical elements. For example, the energy storage device may include an electric motor or generator configured to accelerate or decelerate the rotational rate of a flywheel that mechanically stores energy in the form of rotational kinetic energy. The electric generator may also power a pump configured to compress and / or expand a gas, such as air, within a tank. It should be noted that at least a portion of the energy stored in the energy storage device can be extracted at a later point in time. Many such energy storage devices or mechanisms are available.

[0188] Electrical power can also be directly transferred to the second actuator, for example, via an electrical conductor. In some embodiments, the second actuator can instantaneously consume power. The second actuator can be any actuator of a device or device assembly associated with the boundary device 95. For example, the second actuator can be used to actuate the downstream IMSA 110. Thus, a portion of the power extracted from the fluid by the upstream IMSA 104 can be transferred to the downstream IMSA 110, whereby the power is reinjected into the fluid. In some embodiments, the second actuator can also be used to... Figure 7 Power is provided by a separate device or mechanism not shown in the diagram.

[0189] The electricity provided by the upstream IMSA 104 can also be decomposed and used to drive the second actuator, the third actuator, and amplify the energy contained, for example, in an energy storage device. In some embodiments, the power extracted from the fluid by the upstream IMSA 104 and applied to a drive shaft rigidly connected to the propeller blades of the upstream IMSA 104 is mechanically transferred to the downstream IMSA 110. This transfer can be facilitated in several ways. For example, the drive shaft rigidly attached to the propeller blades of the upstream IMSA 104 (referred to as the "upstream drive shaft") can also be rigidly connected to the drive shaft rigidly connected to the propeller blades of the downstream IMSA 110 (referred to as the "downstream drive shaft"). In other words, the upstream drive shaft can be the same as the downstream drive shaft. In such a configuration, the upstream rotor and downstream rotor of the upstream IMSA 104 and the downstream IMSA 110 rotate in the same direction. In other embodiments, the upstream drive shaft can transfer power to the downstream drive shaft via a transmission, gear train, or a series of gears and a secondary or auxiliary drive shaft. In some embodiments, a clutch may also be present along the load path between the upstream and downstream drive shafts. In some embodiments, the gear ratio or transmission ratio of the mechanical connection between the upstream and downstream drive shafts may be reconfigured. In other words, the gear ratio may be changed, or the gears may be changed.

[0190] In some embodiments, the upstream and downstream rotors of the upstream IMSA 104 and downstream IMSA 110 rotate in opposite directions. This configuration can reduce any power losses associated with the IMSA components. This may be a result of the downstream IMSA 110 eliminating any vortices imposed on the flow by the upstream IMSA 104.

[0191] In some embodiments, the angle of attack of the propeller blades of the upstream IMSA 104 or downstream IMSA 110 relative to the fluid can be controlled by a pitch control mechanism at the rotor hub (such as rotor hub 107). This pitch control mechanism and the associated pitch degree of freedom, or "DOF," may comprise an electric motor and a disc brake. As an alternative to or in parallel with the disc brake, some embodiments may also include a mechanical lock, which can be configured to lock the propeller blade's pitch DOF at a given pitch angle relative to the rotor hub. The pitch control mechanism may also include a hydraulic system and mechanical linkages, such as those found in common pitch mechanisms in conventional helicopters or propellers. The pitch control mechanism and pitch DOF of the propeller blades of the upstream IMSA 104 or downstream IMSA 110 may also be configured to allow the propeller blades to feather. The pitch angle and the rotational rate of the propeller blades can be controlled, thereby allowing adjustment of the IMSA assembly's influence on the fluid. This will allow for optimization of the performance of IMSA components for different flow conditions, such as different free-flow velocities.

[0192] exist Figure 7 In the illustrated IFMA configuration, the downstream IMSA 110 is configured to balance, eliminate, or counteract the effects of the upstream IMSA 104 and boundary device 95 on the fluid. In this way, the fluid velocity distribution in the far wake (as shown in velocity distribution diagram 103) is substantially equal to the free-flow fluid velocity distribution (as shown in velocity distribution diagram 101). During nominal cruise, the power consumed by the downstream IMSA 110 in this process is typically greater than the power extracted by the upstream IMSA 104.

[0193] The downstream IMSA 110 is configured to apply a positive rate of momentum change to the fluid, i.e., to accelerate the fluid in the negative x-direction. As a result, in the isolated case, the induced velocity of IMSA 110 in the far wake of IMSA 110 points in the negative x-direction of the BAF. The induced velocity of the downstream IMSA 110 in the far wake can be considered to counteract the induced velocity of the upstream IMSA 104 in the far wake.

[0194] Within the simplified framework of lift line theory, the desired induced velocity distribution in the far wake of the downstream IMSA 110 can also be considered as generated by free vortices released into the wake by the propeller blades of the downstream IMSA 110. This is similar to the vortex release of helicopter rotors and conventional propeller blades.

[0195] In the isolated configuration, the aforementioned induced velocity distribution of the downstream IMSA 110 can also be considered as being generated by a suitable lift or thrust distribution along the propeller blades of the downstream IMSA 110. Since the induced velocity of the downstream IMSA 110 in the isolated configuration points downstream (i.e., the negative x-direction of BAF) for at least a portion of the downstream IMSA 110, the operation of the downstream IMSA 110 is similar to the operation of a conventional propeller in a conventional fixed-wing aircraft. In other words, corresponding to the induced velocity distribution in the wake of the downstream IMSA 110 in the isolated configuration, the thrust experienced by at least a portion of the blades of the downstream IMSA 110 has a non-zero component in the positive x-direction of BAF, as shown by thrust vector 128.

[0196] It should be noted that in some embodiments, there is no designated downstream IMSA, for example... Figure 7 The downstream IMSA 110. In such embodiments, the power extracted by the upstream IMSA can be stored or used to provide thrust via alternative fluid manipulation devices or methods. It should be noted that Figure 7 The upstream IMSA 104 in the BAF exerts a force in the negative x-direction. During cruise flight, this force will need to be counteracted by adequate thrust to maintain a constant cruise speed for the BAF. This thrust can be provided in several ways. Figure 7 In this embodiment, the thrust is provided by the downstream IMSA 110. In other embodiments, the thrust may be provided by different thrust devices.

[0197] In some embodiments, this thrust can be provided by increasing the radius of the propeller blades of the upstream IMSA. In such embodiments, the length of the propeller blades of the upstream IMSA is greater than... Figure 7 The radius of the flow tube 100 shown. In this case, the propeller blade of the upstream IMSA 104 can have two distinct parts. The first part can be the portion of the propeller blade located within a first internal flow tube, which can have a radius similar to... Figure 7 The flow tube 100 shown has similar dimensions and configuration and achieves the same Figure 7 The flow tube 100 shown serves a similar purpose. The first part of the propeller blades of the upstream IMSA can be configured to achieve the same purpose as... Figure 7The entire upstream IMSA 104 shown serves a similar purpose. The remaining second section of the propeller blades of such an upstream IMSA can be configured to generate the desired thrust described above. The wake of the second section forms an outer flow tube that surrounds or encloses the inner flow tube. The induced velocity of the thrust-generating section of the upstream IMSA can be uniform throughout the entire outer flow tube in the far wake in order to minimize induced power consumption. Thus, the power extracted by the first section of the propeller blades is directly and mechanically transferred to the second section of the propeller blades via a rigid structural connection between the first and second sections of the propeller blades. A portion of the energy loss of the fluid within the inner flow tube is used to generate thrust and increase the energy of the fluid within the outer flow tube. It should be noted that such a configuration will generate a momentum deficit in the wake within the inner flow tube because, as mentioned above, there is no designated downstream IMSA in such embodiments. Such a configuration will result in a non-uniform velocity distribution in the far wake and will therefore be less efficient than a configuration with a substantially uniform velocity distribution throughout the far wake (i.e., in both the inner and outer flow tubes). However, such a configuration can still provide an improvement over embodiments of the prior art due to the recovery of a portion of the energy loss attributable to viscous drag.

[0198] In other embodiments, the aforementioned momentum loss in the internal flow tube is eliminated by adding a downstream IMSA to the above configuration.

[0199] In other embodiments, the downstream IMSA may extend beyond the flow tube 100. For example, the length of the propeller blades of the downstream IMSA may be greater than the radius of the flow tube 100. In this way, the induced power consumption of the downstream IMSA that generates thrust can be reduced. In this configuration, a uniform far-wake induced velocity distribution can be achieved on both the inner and outer flow tubes of the downstream IMSA, which is desirable for minimizing induced power.

[0200] In other embodiments, with Figure 7 Compared to the illustrated embodiments, both the upstream IMSA and the downstream IMSA can include rotor tip extensions. In some such embodiments, the rotor diameters of the upstream IMSA and the downstream IMSA are substantially the same. In other such embodiments, this is not necessarily the case. As previously described, the rotor tip extensions create an outer flow tube surrounding the inner flow tube. The interiors of the rotors of the upstream IMSA and the downstream IMSA can be aligned with... Figure 7The rotor exterior can be configured in the same manner as described in the context of flow tube 100. The rotor exterior can be configured to generate a desired amount of thrust while minimizing total power consumption, which includes form drag and induced drag. For example, the exteriors of the upstream and downstream IMSAs (i.e., the portions associated with the outer flow tube) can be configured similarly to a coaxial rotor rotating in opposite directions, with both the upstream and downstream IMSAs generating thrust in the positive x-direction of the BAF. In another instance, the exterior of the upstream IMSA can be configured to generate thrust directed in the positive x-direction of the BAF, and the magnitude of this thrust is greater than the desired thrust required for the exteriors of both the upstream and downstream IMSAs. Therefore, the exterior of the downstream IMSA can be configured to generate thrust directed in the negative x-direction of the BAF. This configuration reduces the induced power consumption associated with the exteriors of the upstream and downstream IMSAs compared to a configuration where the thrust vectors of both the upstream and downstream IMSAs are directed in the positive x-direction of the BAF.

[0201] In some embodiments, there may be more than one single upstream propeller (such as upstream IMSA 104) and more than one single downstream propeller (such as downstream IMSA 110). Several propellers may be located within the flow tube 100 near the boundary device 95. Using several propellers within the flow tube 100 may be desirable in order to maintain a desired velocity distribution within the flow tube 100. For example, consider a cylindrical boundary device with a tapered end, such as the fuselage of a conventional commercial transport aircraft. In this case, it is convenient and desirable to arrange several rotors or propellers along the length of the fuselage. For example, the propellers may be located along the x-axis of the BAF, such as... Figure 6 The location shown is the same as the location of the duct (such as the third IMCA 81). The propeller can be mounted on the fuselage in a manner that maintains the fuselage diameter, i.e., the fuselage is located within the propeller hub or passes through the center of the propeller hub. The circular shape of the fuselage facilitates the rotation of the rotor around the fuselage. The rotor hub can form a rigid ring capable of rotating around the fuselage. For example... Figure 7 As shown, in this configuration, the axis of rotation is parallel to the longitudinal axis of the cylindrical fuselage. Several propeller blades can be attached to the rotor hub and perform the desired fluid flow manipulation. An electric motor can power the rotor hub and extract power from the rotation of the rotor hub relative to the fuselage, depending on whether the rotor is in an "upstream" or "downstream" position or configuration. In such a configuration, at least theoretically, the fuselage can be infinitely long, and during nominal constant speed cruise, the flow field within the flow tube 100 remains constant on average, where the average is calculated along the x-axis of the BAF at a distance between propellers evenly spaced along the fuselage length.

[0202] The length of each rotor blade can be a fraction of the fuselage diameter. In the absence of a slip reference, the length of the rotor blade can be approximately the thickness of the boundary layer at that particular location in the flow. In some embodiments, in the absence of a slip reference, the ratio of the rotor blade length to the maximum thickness of the boundary layer along the outer surface of the boundary device (such as the fuselage) is less than 2. In some embodiments, this ratio is less than 5. In some embodiments, this ratio is less than 10. In some embodiments, this ratio is less than 100.

[0203] Figure 6 A cross-sectional view of another IFMA configuration is shown. Figure 6 Some features of the device shown and some operating principles of the device are related to Figure 7 The devices shown are similar, therefore in Figure 6 The context will not describe it in detail, and vice versa.

[0204] Figure 6 A boundary device 70 moving relative to the surrounding fluid is depicted. The boundary device 70 has a leading edge point 73 and a trailing edge point 74. The leading and trailing edge points can also be edges, such as the leading or trailing edge of a wing or airfoil. In the case of a wing, the leading and trailing edges can be considered as the leading and trailing stagnation lines under specific flow conditions. In this embodiment, the boundary device is a rigid body that can be described as a thin shell, having a closed outer surface 71 and an inner surface 72. In this embodiment, the boundary device 70 has a rotational shape, i.e., it is axially symmetrical about an axis passing through the leading edge point 73 and the trailing edge point 74.

[0205] Boundary device 70 can be the hull of a ship or the fuselage of an aircraft. In other embodiments, boundary device 70 can have different geometries. For example, the shape of the boundary device can be similar to that of boundary device 61 shown in FIG. 5. Suitable geometries can be found for any given application. Boundary devices can be manufactured using a variety of existing methods and materials.

[0206] The "Boundary Device Frame" or "BAF" can be defined as follows: The origin is located at the geometric centroid of the volume enclosed by the outer surface 71 of the boundary device 70. The x-axis coincides with the line connecting the leading edge point 73 and the trailing edge point 74, and points towards the leading edge point 73. Unless otherwise specified, the z-axis points perpendicularly to the page of the accompanying drawing.

[0207] Three velocity distribution diagrams 76-78 are shown. Each arrow in the velocity distribution diagram indicates the velocity vector of the incremental fluid element relative to the boundary device, where the incremental fluid element is located at the base of the arrow at the time point in time at which its velocity is measured relative to the boundary device. The line connecting the tips of the arrows in the velocity distribution diagram describes a continuous velocity distribution.

[0208] The boundary device 70 moves relative to the surrounding fluid. In the simplified case illustrated, the free flow velocity is spatially uniform and temporally constant. Figure 6 In the diagram, the free-flowing fluid relative to the boundary device 70 is guided parallel to the x-axis of the BAF and in its opposite direction, i.e., from the top to the bottom of the diagram. Upstream of the distal end of the boundary device 70, the velocity of the incremental fluid element is approximately equal to the free-flowing velocity. Therefore, the velocities in the velocity distribution diagram 76 are spatially uniform and temporally constant, with magnitude and direction equal to the free-flowing velocity relative to the boundary device.

[0209] Velocity distribution diagram 77 depicts the velocity distribution near the boundary device 70. In this embodiment, a no-slip condition exists on the outer surface 71 of the boundary device 70. In other embodiments, non-zero slip velocity may exist along the outer surface 71. Velocity distribution diagram 77 and... Figure 7 The velocity distribution diagram shown is similar to that in diagram 102. Therefore, in Figure 6 The characteristics of the velocity distribution map and its alternative embodiments will not be described in detail in the context of this document.

[0210] Velocity distribution diagram 78 depicts the velocity distribution in the far wake of boundary device 70. In a simplified ideal case, velocity distribution diagram 78 is essentially equal to velocity distribution diagram 76, as shown below. Figure 6 As shown. It should be noted that there is a momentum deficit due to resistance associated with the IMCA component, for example, this can be caused by pressure resistance or viscous resistance. In other embodiments, there may also be a momentum deficit due to resistance associated with the boundary device 70.

[0211] According to some embodiments, the boundary device (such as boundary device 70) is provided with intentional fluid manipulation means. Figure 6 In the illustrated embodiment, the intentional fluid manipulation device can be described as an IMCA assembly comprising a first IMCA 79, a second IMCA 80, a third IMCA 81, and a fourth IMCA 82. Four IMCAs are shown in this embodiment; however, more or fewer IMCAs may be used.

[0212] Each IMCA (such as the first IMCA 79) can be described as a circular conduit. Figure 6In the illustrated embodiment, each conduit is configured to generate lift with a component in the radially outward direction. The central axis of each circular conduit coincides with and points in the direction of the x-axis of the BAF. Roughly speaking, the effect of the conduit on fluid flow can be considered as being generated by vortex rings in the lift line theory. In this simplified model, each vortex ring of each IMCA lies in a plane parallel to the yz plane. When viewed along the positive x-direction, the circulation of each vortex ring surrounds each ring in a clockwise direction. Each IMCA has a leading edge (such as the leading edge 83 of the first IMCA 79) and a trailing edge (such as the trailing edge 89 of the third IMCA 81).

[0213] Streamline 75 describes the boundary of the flow tube, which has a circular cross-section when viewed along the x-direction. Figure 6 The dashed streamline 75 schematically indicates the approximate location of the stagnant streamline of the first IMCA 79, i.e., the streamline incident on the stagnant line at the leading edge of the first IMCA 79. The volume surrounded by all such streamlines can be described as a flow tube.

[0214] It should be noted that Figure 6 The flow tube 75 shown is merely an example of a specific operating condition and configuration for the IMCA assembly. For other operating conditions, such as different free-flow velocities, the shape of the flow tube 75 may differ. For example, the flow tube 75 may pass through the interior region of the second IMCA 80, rather than also incident on the leading edge stagnation line of the second IMCA 80. To avoid flow separation and the associated increase in pressure drag, it may be desirable that the IMCA is not located within the wake of the upstream IMCA, i.e., along or near the stagnation streamline of the upstream IMCA. However, this can increase the viscous skin frictional drag losses associated with the IMCA assembly.

[0215] Each IMCA in the IMCA assembly is rigidly connected to the boundary device 70 via a connecting device. For clarity, in Figure 6 The device is not shown in the image.

[0216] In other embodiments, the IMCA (such as IMCA 79) may comprise several conduits. In such configurations, the IMCA may be described as a multi-element airfoil, rather than... Figure 6 The illustrated unit airfoil. For example, an IMCA can comprise a four-element airfoil, each part effectively forming a separate duct. Such a configuration can increase the maximum lift coefficient of the IMCA.

[0217] The effect of the IMCA component on fluid flow is to generate a localized induced velocity distribution in the vicinity of the IMCA component. Typically, the induced velocity within the IMCA component, i.e., the induced velocity near the central axis of the IMCA component, has a non-zero component in the positive x-direction of the BAF. The desired induced velocity distribution can be achieved by placing the IMCA (such as the first IMCA 79 and the second IMCA 80) at appropriate locations within the fluid flow and by selecting an appropriate circulation intensity or an appropriate lift per unit circumference.

[0218] According to some embodiments, the IMCA component is configured to reduce the flow velocity at the outer surface 71 of the boundary device 70 in a fully slipped reference condition compared to the fully slipped reference condition. This reduction can result in lower skin frictional resistance at the outer surface 71 in a no-slip condition. For example, this reduction can be caused by a reduction in effective free flow at the outer surface 71, the establishment or maintenance of laminar flow on the outer surface 71, or a reduction in the Reynolds number of the flow at the outer surface 71. For some operating conditions, this reduction in resistance associated with the boundary device 71 can be greater than the increase in resistance of the IMCA component.

[0219] Figure 8 This is a cross-sectional view of IFMA Configuration 150. The center of mass of IFMA Configuration 150 moves at a velocity in an inertial frame of reference, where the magnitude and direction of this velocity are constant in space and time. This velocity is aligned with the X-axis, i.e., pointing in the positive X direction.

[0220] An upstream IMSA 151 exists, which in this embodiment can be described as a propeller. A cross-sectional view of the upstream IMSA 151 shows a first propeller blade 152 and a second propeller blade 154. The trailing edge 153 of the first propeller blade 152 and the leading edge 155 of the second propeller blade 154 are also visible. The propeller blades are structurally supported by a rotor hub 156. The thrust of the IMSA 151 is represented by a thrust vector 183. At station 179, in this embodiment, a positive rate of change of momentum is applied to the fluid via the upstream IMSA 151.

[0221] A downstream IMSA 166 exists, which in this embodiment can be described as a propeller. A cross-sectional view of the downstream IMSA 166 shows a first propeller blade 167 and a second propeller blade 169. The trailing edge 168 of the first propeller blade 167 and the leading edge 170 of the second propeller blade 169 are also visible. The propeller blades are structurally supported by a rotor hub 171. The thrust of the IMSA 166 is represented by a thrust vector 184. At station 181, a negative rate of change of momentum is applied to the fluid via the downstream IMSA 166. Downstream of the IFMA configuration 150, the direction of the flow within the flow tube 176 relative to the IFMA configuration 150 is indicated by arrow 185.

[0222] Intermediate IMSA 161 is also shown. In this embodiment, intermediate IMSA 161 can be described as a wing. For simplicity, wing 161 is a straight wing. For example, the wing can be rigidly attached to the fuselage. For clarity, the fuselage is not shown. Intermediate IMSA 161 can be configured in a manner similar to the fixed wing of a conventional fixed-wing aircraft. Intermediate IMSA 161 generates lift in the positive Y direction and the negative X direction. It should be noted that, for illustrative purposes, the relevant deflection of the flow direction within flow tube 176 has been amplified.

[0223] The intermediate IMSA 161 includes an outer surface 162, a trailing edge 165, and a matrix material 164. The matrix material 164 may comprise a metal such as aluminum or steel, or a composite material such as glass fiber or carbon fiber. The upstream IMSA 151 is rigidly attached to the intermediate IMSA 161 via a hollow link 157 having an outer surface 158. The downstream IMSA 166 is rigidly attached to the intermediate IMSA 161 via a link 172 having an outer surface 173.

[0224] In other embodiments, link 157 or link 172 is rotatably connected to the intermediate IMSA 161 or an associated intermediate support device. In some embodiments, link 157 or link 172 is rotatably connected to hub 157 or hub 171, respectively. This rotatable connection allows the configuration to adapt to different operating conditions. During cruise or maneuvering, the rotatable connection can facilitate control of the pitch angle of the intermediate IMSA 161 and any associated devices, such as the fuselage.

[0225] In this particular embodiment, the magnitude of the upstream thrust vector 183 is greater than the magnitude of the downstream thrust vector 184. Therefore, the upstream IMSA 151 and the downstream IMSA 166 generate a net thrust with a non-zero component in the positive X direction. This net thrust thus helps to counteract any traction drag acting on the IFMA configuration 150. In other embodiments, the magnitudes of these thrust vectors may be substantially the same. In other embodiments, the magnitude of the upstream thrust vector 183 is smaller than the magnitude of the downstream thrust vector 184.

[0226] The upstream IMSA 151 is configured to increase the local free-flow velocity of the intermediate IMSA 161 to a value greater than the free-flow velocity of the intermediate IMSA 161. The downstream IMSA 166 is configured to recover at least a portion of the excess thrust and excess energy transferred to the fluid by the upstream IMSA 151 throughout the process. Compared to a baseline case where the same intermediate IMSA 161 produces the same amount of lift without the upstream IMSA 151 and downstream IMSA 166, the induced drag of the intermediate IMSA 161 can be reduced.

[0227] As a result, the average flow velocity at station 180 is greater than that at stations 178 and 182. The flow tube 176 at station 180 has a smaller flow cross-sectional area than the flow tubes at stations 182 or 178. The increase in the flow cross-sectional area of ​​the flow tube 176 at station 182 compared to station 180 can be considered as an increase in the aspect ratio or span of the intermediate IMSA 161.

[0228] Figure 9 yes Figure 8 The image shows a front view of the IFMA configuration 150. When viewed in the negative X direction, the upstream IMSA 151 and downstream IMSA 166 can rotate counterclockwise. Alternatively, the upstream and downstream IMSA can rotate in opposite directions.

[0229] In other embodiments, the upstream IMSA or downstream IMSA may comprise a plurality of individual propellers. These propellers may be offset from each other in the flow direction. For example, the upstream IMSA or downstream IMSA may comprise coaxial propellers rotating in opposite directions. In some embodiments, the upstream IMSA or downstream IMSA may comprise a plurality of propellers distributed along the width of the flow tube. In other words, the propellers may also be offset from each other in a direction transverse to the flow direction.

[0230] The path followed by the tip of the propeller blade of the upstream IMSA 151 is shown by dashed line 186. Figure 9 The dashed line 187 shows the path followed by the tip of the propeller blade of the downstream IMSA 166.

[0231] Figure 10 , Figure 11 , Figure 12 and Figure 13 Perspective, side, top, and rear views of the IFMA configuration 200, including the intermediate IMSA 201, are shown. For simplicity, the intermediate IMSA 201 can be configured as a straight wing with an elliptical aspect ratio, constant airfoil shape, and zero twist. For example, the wing can be rigidly attached to the fuselage. The fuselage is not shown for clarity. The intermediate IMSA 201 can be configured in a similar manner to the intermediate IMSA 161, or vice versa. The intermediate IMSA 201 can be configured in a manner similar to the wing or horizontal rudder of an aircraft or ship. The intermediate IMSA 201 includes an outer surface 202 and a trailing edge 205.

[0232] IMCA 206 is configured to increase the local free flow at intermediate IMSA 201. In other words, the flow velocity at station 224 is artificially increased by IMCA 206 compared to the flow velocity at upstream station 223 or downstream station 224. IMCA 206 can be considered as a conduit.

[0233] IMCA 206 is rigidly attached to IMSA 201. IMCA 206 includes an outer surface 207 and a trailing edge 210. In this embodiment, when viewed in the flow direction, IMCA 206 is rectangular in shape, as shown below. Figure 13 As shown. In other embodiments, the shape of IMCA206 may be elliptical or circular. In other embodiments, IMCA may describe a mirrored bell shape, wherein the mirror plane coincides with the wingspan of the wing.

[0234] IMCA 206 can be configured not to release any vorticity within the framework of lift line theory. In other words, the circulation associated with IMCA 206 is constant along the wingspan of IMCA 206. In other embodiments, IMCA 206 may also release vortices. For example, IMCA 206 may be configured to contribute to the net lift of IFMA configuration 200. In such embodiments, IMCA 206 can be viewed as a conventional closed wing or annular wing, with the constant wingspan circulation added to the boundary vorticity released into the far wake of IMCA. In other words, IMCA can be viewed as a superposition of IMCA and IMSA. In some embodiments, the intermediate IMSA 201 may also be described as a closed wing.

[0235] The variation of the torsional angle along the span of IMCA 206 is a result of the influence of IMSA 201 on the flow field and the requirements of the boundary vorticity or circulation of IMCA 206.

[0236] In some embodiments, IFMA configuration 200 may include several independent closed airfoils configured in a manner similar to IMCA 206. These independent IMCAs may be offset in the flow direction in a manner similar to that of a multi-element airfoil. Individual independent IMCAs may also be offset in a direction perpendicular to the local flow direction. IMCAs may also be considered to be located within another IMCA. For example, a first circular IMCA may be considered to be concentrically arranged with a second circular IMCA.

[0237] Streamline 222 illustrates the reduction in the cross-sectional area of ​​the flow tube surrounded by IMCA 206 at station 224 due to the accelerated flow via IMCA 206. The cross-sectional area of ​​this flow tube is larger at station 225, corresponding to the larger effective span of IMSA 201.

[0238] Figure 14 This is a cross-sectional view of IFMA configuration 240, which is used in conjunction with... Figure 10The IFMA200 shown is configured in a similar manner. In this embodiment, the conduit 241 releases the eddies into the wake. Therefore, the conduit 241 is also referred to as IMSA 241. IMSA 241 can be considered as a superposition of IMCA and IMSA. IMSA 241 is configured to increase the local free-flow velocity of the intermediate IMSA 247.

[0239] In this embodiment, IMSA 241 is substantially axially symmetrical. IMSA 241 includes an outer surface 242, an inner surface 243, a substrate material 246, and a trailing edge 244. The substrate material 246 may be configured in a similar manner to substrate material 164. The intermediate IMSA 247 is configured in a similar manner to the intermediate IMSA 201. The intermediate IMSA 247 includes an outer surface 248 and a trailing edge 250.

[0240] Flow tube 254 surrounds all streamlines, which encircle IMSA 241, i.e., pass through the interior of IMSA 241. The cross-sectional area of ​​the flow tube at upstream station 255 is larger than that at station 256, while the cross-sectional area of ​​station 256 is smaller than that at downstream station 257.

[0241] Figure 15 This is another perspective view of IFMA configuration 270. Figure 15 Some features of the device shown and some operating principles of the device are consistent with other accompanying drawings (especially...). Figure 7 The apparatus shown in ) is similar, therefore in Figure 15 The context will not describe it in detail, and vice versa.

[0242] IFMA Configuration 270 is depicted as a fixed-wing aircraft, such as a commercial transport aircraft or a jet airliner, such as a Boeing 737 or Airbus A320. It has a fuselage 293, a left wing 300 and a right wing 299, a vertical tail 301 including a rudder, and a left horizontal stabilizer 304 and a right horizontal stabilizer for all-flight operations. During nominal level cruise, the flight direction of IFMA 270 is substantially in the direction of thrust vector 292. During nominal level cruise, the direction of airflow around Configuration 270 relative to the free flow of Configuration 270 is indicated by arrow 305.

[0243] An upstream IMSA 271 exists, which in this embodiment can be described as a ducted fan. In this embodiment, the duct is configured to slow the flow before encountering a fan disk located within the fan. In some embodiments, this can be used to avoid or mitigate wave drag losses associated with the fan disk. The upstream IMSA 271 includes a duct 272 and a fan disk. The upstream IMSA 271 is configured to apply a force to an IFMA configuration 270, directed in the same direction as the mean free flow relative to the IFMA 270, as indicated by thrust vector 281. The upstream IMSA 271 is configured to extract energy from the surrounding fluid. The IFMA 270 is configured to transfer at least a portion of the energy to the downstream IMSA 282. As described above, the transfer can be facilitated by connecting the fan disk of the upstream IMSA 271 to the fan disk of the downstream IMSA 282 via a mechanical drive shaft. The fan disk of the upstream IMSA 271 can transfer power to the fan disk of the downstream IMSA 282 via, for example, a direct, rigid mechanical connection. The fan disk of the upstream IMSA 271 can transmit power to the fan disk of the downstream IMSA 282 via a drive shaft and gear train. The drive shaft can pass through the fuselage 293. The fan disk of the upstream IMSA 271 can transmit power to the fan disk of the downstream IMSA 282 via a generator, which transmits power to an electric motor via wires or conductors, and the electric motor then transmits power to the fan disk of the downstream IMSA 282. The upstream IMSA 271 and downstream IMSA 282 are rigidly attached to the fuselage 293.

[0244] In some embodiments, the downstream IMSA 282 may be described as a turbofan engine. Where power is transferred from the upstream IMSA 271 to the downstream IMSA 282, the downstream IMSA 282 may be described as a hybrid electric turbofan engine. In other embodiments, the downstream IMSA 282 may be described as a turbojet engine. The downstream IMSA 282 includes a duct 283. The downstream IMSA 282 is configured to apply a force to embodiment 270 directed in the opposite direction to the mean free flow relative to the IFMA configuration 270, as indicated by thrust vector 292. In this embodiment, the thrust magnitude of the downstream IMSA 282 is greater than the thrust magnitude of the upstream IMSA 271. Therefore, the downstream IMSA 282 is configured to meet any unresolved thrust requirements of the IFMA configuration 270. In other embodiments, at least one separate propulsion unit or engine may be attached to at least one wing. For example, such a separate engine may be a conventional turbofan or a hybrid electric turbofan.

[0245] The upstream IMSA 271 can be configured to artificially reduce at least the local free flow of the fuselage 293, and the downstream IMSA 282 is configured to counteract at least a portion of the reduction in velocity in the wake of the fuselage 293 and near the fuselage 293.

[0246] In some embodiments, the upstream IMSA 271 can be considered as generating an artificial boundary layer for the fuselage 293, wherein the boundary layer is generally surrounded by flow channels passing through the interior of the conduit 272. It should be noted that the fuselage 293 and the artificial boundary layer can also be considered as being surrounded by a natural boundary layer. The upstream IMSA 271 is configured to alter the velocity distribution within the artificial boundary layer or near the wetted surface of the fuselage 293 in such a way that it reduces the overall drag of the fuselage 293 and the IFMA configuration 270 compared to the baseline case where the upstream IMSA 271 is absent, i.e., compared to the case where the fuselage is surrounded only by a natural boundary layer. For example, the reduction in drag can include a reduction in viscous drag, and / or a reduction in wave drag or compressive drag. The drag reduction is associated with altering the spatial distribution of fluid velocity relative to the fuselage 293 through the upstream IMSA 271 and, to a lesser extent, the downstream IMSA 282.

[0247] Reducing the magnitude of the local free-flow fluid velocity in the fuselage 293 via the upstream IMSA 271, reducing the fluid velocity at and relative to the wetted surface of the fuselage 293, and generating a more favorable velocity distribution near the wetted surface of the fuselage 293 can contribute to the reduction of viscous drag. For example, a more favorable velocity distribution may include a reduced peak spatial fluid velocity gradient or a reduced spatial average magnitude of the spatial fluid velocity gradient near the IMSA configuration 270.

[0248] The reduction in wave drag can result from a smoother change in the fluid flow direction as the fluid flows around the IFMA configuration 270, or from a smoother displacement of the fluid by the IFMA configuration 270. This is facilitated by the deceleration of the fluid flow by the upstream IMSA 271 and the acceleration of the fluid flow by the IMSA 282. Therefore, the intensity of the disturbance to the fluid flow by the IFMA configuration 270 can be reduced, which can reduce the wave drag associated with the IMMA configuration 270.

[0249] The reduction in drag can decrease the power consumption of the IFMA configuration 270 compared to the baseline case, or, for a given power consumption, allow the IFMA configuration 270 to move faster relative to the fluid. This can increase the range or maximum speed of the IFMA configuration 270.

[0250] Figure 16 This is a top-down view of another IFMA configuration 315. Figure 16 Some features of the device shown and some operating principles of the device are consistent with other accompanying drawings (especially...). Figure 3The apparatus shown in ) is similar, therefore in Figure 16 The context will not describe it in detail, and vice versa.

[0251] IFMA configuration 315 can be described as a quadcopter helicopter or quadcopter aircraft. Embodiment 315 can also be described as an octocopter or multirotor. IFMA configuration 315 includes four IMSA components, such as IMSA components 316, 339, 362, and 385. Each IMSA component includes an upstream IMSA (such as upstream IMSA 365 of IMSA component 362) and a downstream IMSA (such as downstream IMSA 375 of IMSA component 362).

[0252] Each upstream or downstream IMSA can be described as a propeller. Each propeller may include a first propeller blade (such as the first propeller blade 377 of the downstream IMSA 375) and a second propeller blade (such as the second propeller blade 378 of the downstream IMSA 375). In other embodiments, the propeller may include at least one blade or only one blade. In other embodiments, the propeller may include at least three blades. A propeller hub (such as propeller hub 379 or 369) connects each propeller to a drive shaft or actuator.

[0253] IFMA configuration 315 is displayed as hovering. The flow induced by the IMSA component is directed in a vertically downward direction, essentially aligned with the thrust vector 380.

[0254] An upstream IMSA (such as upstream IMSA 365) is configured to generate thrust acting on IFMA configuration 315 in an upward direction, as shown by thrust vector 370 or 347. A downstream IMSA (such as downstream IMSA 375) is configured to generate thrust acting on configuration 315 in a downward direction, as shown by thrust vector 380 or 357.

[0255] Compared to the case where the IMSA assembly comprises only one IMSA (i.e., only the upstream IMSA), the upstream IMSA is configured to increase the local free-flow velocity relative to itself. The corresponding downstream IMSA is configured to counteract any excess momentum in the fluid flow in the wake of the upstream IMSA. It should be noted that during nominal hover, the sum of the net thrust generated by all four IMSA assemblies is substantially equal to the weight of the IFMA configuration 315. During nominal hover, the net thrust generated by any one IMSA assembly is substantially equal to the net thrust generated by any of the other four IMSA assemblies. During nominal hover, the magnitude of the thrust vector of the downstream IMSA is smaller than the magnitude of the thrust vector of the corresponding upstream IMSA.

[0256] Each IMSA component in IFMA configuration 315 also includes a nacelle, such as nacelle 340, which houses actuators, generators, gearboxes, or drive shafts that facilitate the transfer of energy from the downstream IMSA to the upstream IMSA. It should be noted that a downstream IMSA of the first IMSA component can also transfer power to the upstream IMSA of the second IMSA component.

[0257] exist Figure 16 In the configuration shown, the induced power consumption of the IMSA assembly is lower than that of the equivalent baseline or reference configuration, where the effect of the downstream IMSA on the fluid is negligible, meaning the thrust of the upstream IMSA is essentially equal to the net thrust requirement. In the baseline configuration, the IMSA assembly can be considered to consist only of the upstream IMSA. It should be noted that, as mentioned above, in some embodiments, the IMSA (such as the upstream IMSA) may comprise several propellers or thrust devices. In this case, the baseline configuration is the same as that of a conventional quadcopter helicopter.

[0258] Each IMSA assembly is rigidly connected to the fuselage 408 via a beam. Each beam is enclosed in an aerodynamic or hydrodynamic fairing, such as beam fairing 341. In some embodiments, the beam fairing is rotatably connected to the beam, i.e., capable of rotating relative to the fuselage 408 and the corresponding nacelle. In some embodiments, at least one beam fairing is used to generate lift during nominal level cruise, wherein the lift is generated in a manner similar to that of a conventional fixed-wing aircraft, wherein the fuselage long axis is oriented in a substantially horizontal direction, i.e., the direction of motion in the inertial frame, and wherein at least one IMSA assembly is configured to generate net thrust that counteracts drag acting on the IFMA configuration 315. It should be noted that in some embodiments, the pitch angle of the propellers of some IMSAs can be varied. It should be noted that during cruise, the propellers of some IMSA assemblies can be feathered.

[0259] In some embodiments, the upstream IMSA may be powered by an electric motor. In some embodiments, the upstream IMSA may be powered by a brushless DC motor containing permanent magnets. In some embodiments, the IMSA assembly may be powered by an AC induction motor. In some embodiments, the drive shaft of the upstream IMSA is rigidly connected to the drive shaft of the corresponding downstream IMSA. In some embodiments, an actuator powering the drive shaft is rigidly connected to the drive shaft in a direct drive configuration. In some embodiments, the actuator is connected to the drive shaft via a clutch or gear train. For example, power may be provided by a battery, an internal combustion engine, or a turboshaft engine. Actuators powering one or more IMSA assemblies may also be located within the housing 408. For example, power may be transferred mechanically or electrically from such actuators to the IMSA assemblies.

[0260] In some implementations, the upstream or downstream IMSA includes several propellers. For example, the upstream or downstream IMSA may include at least two coaxial propellers rotating in opposite directions or in the same direction.

[0261] It should be noted that the propellers of the upstream IMSA and the corresponding downstream IMSA do not need to be in phase and do not need to rotate at the same angular velocity during nominal operation. In some embodiments, there exists an optimal phase angle for a given interval between the upstream and downstream IMSA, where optimality may refer to minimizing the aircraft's operating costs or maximizing its durability.

[0262] Figure 17 This is another IFMA configuration 425 oblique top view. Figure 17 Some features of the device shown and some operating principles of the device are consistent with other accompanying drawings (especially...). Figure 3 The apparatus shown in ) is similar, therefore in Figure 17 The context will not describe it in detail, and vice versa.

[0263] The IFMA configuration 425 can be described as a conventional helicopter. The IFMA configuration 425 includes a fuselage 448 with windows 449 and a tail rotor assembly 451.

[0264] IFMA configuration 425 is displayed as being in nominal hover, where the induced flow is directed vertically downward, as shown in flow direction 456.

[0265] The upstream IMSA 426 is configured to generate thrust acting on the IFMA configuration 425 in an upward direction, as shown by thrust vector 434 associated with the first rotor blade 427 or thrust vector 435 associated with the second rotor blade 430. The first blade 427 and the second blade 430 are connected to the drive shaft via a rotor hub 433. The drive shaft may be surrounded by an aerodynamic fairing 436.

[0266] The downstream IMSA 437 is configured to generate thrust acting on embodiment 425 in a downward direction, as shown by thrust vector 445 associated with the first rotor blade 438 or thrust vector 446 associated with the second rotor blade 441. The first blade 438 and the second blade 441 are connected to a drive shaft via rotor hub 444. The drive shaft may be surrounded by an aerodynamic fairing 447. In some embodiments, the drive shafts of the upstream IMSA 426 and the downstream IMSA 437 are identical. In other embodiments, the drive shaft of the upstream IMSA 426 passes coaxially through the center of the drive shaft of the downstream IMSA 437. In other embodiments, a fuselage 448 is located between the upstream IMSA 426 and the downstream IMSA 437.

[0267] The IFMA Configuration 425's main rotor system can be described as an IMSA assembly comprising the upstream IMSA 426 and the downstream IMSA 437. Figure 17 In the hovering configuration shown, the induced power consumption of the IMSA assembly is lower than that of the equivalent baseline or reference configuration, where the impact of the downstream IMSA on the fluid is negligible, meaning the thrust of the upstream IMSA is essentially equal to the net thrust requirement. In the baseline configuration, the IMSA assembly can be considered to consist only of the upstream IMSA. In this case, the baseline configuration is the same as that of a conventional helicopter.

[0268] Within the nominal level cruise operating conditions, at least a portion of the downstream IMSA 437 is no longer located in the wake of the upstream IMSA 426. When this portion is sufficiently large, the downstream IMSA 437 can feather. In some embodiments, feathering of the downstream IMSA 437 may involve reducing the angular velocity of the rotor blades to zero. In some embodiments, the rotor blades of the downstream IMSA 437 are folded. For example, the rotor blades may be folded into an aerodynamic fairing for nominal level cruise. In other embodiments, during nominal level cruise, the downstream IMSA 437 may be configured to generate thrust or lift with a positive component along the lift vector of the upstream IMSA 426. In this respect, the downstream IMSA 437 and the upstream IMSA 426 may operate or be configured in a manner similar to the rotors of a coaxial helicopter in the prior art.

[0269] It should be noted that the principles of some embodiments can also be applied to tiltrotor aircraft. For example, a single rotor of a tiltrotor aircraft can be replaced by two rotors separated by a support shaft, similar to two rotors, namely the upstream IMSA 426 and the downstream IMSA 437, as shown below. Figure 17 As shown. In this way, some of the advantages of the embodiments can be applied to cruise flight and hovering flight.

[0270] Figure 18 This is another oblique side view of IFMA configuration 470. Figure 18 Some features of the device shown and some operating principles of the device are consistent with other accompanying drawings (especially...). Figure 3 The apparatus shown in ) is similar, therefore in Figure 18 The context will not describe it in detail, and vice versa.

[0271] The IFMA configuration 470 can be described as a wind turbine. Wind direction is indicated by arrow 501. The IFMA configuration 470 includes a vertical support 496 rotatably connected to a horizontal nacelle 495, with the rotation axis parallel to the vertical axis. An upstream IMSA 471 and a downstream IMSA 483 are rotatably connected to the nacelle 495, with their rotation axes coaxial and parallel to the horizontal axis.

[0272] In this embodiment, the upstream IMSA 471 can be described as a propeller and includes a first blade 472, a second blade 478, and a third blade 475. Each blade is rotatably connected to a rotor hub 481, with the axis of rotation substantially parallel to the long axis of the blade. The pitch angle of each rotor blade can be adjusted according to wind conditions to optimize the performance of the wind turbine, where performance can refer to, for example, the power extracted from the wind. The upstream IMSA 471 is configured to accelerate the fluid flow at the location of the downstream IMSA 483, i.e., to increase the magnitude of the fluid velocity relative to the inertial frame. The upstream IMSA 471 applies a thrust in the upstream direction in embodiment 470, as indicated by thrust vector 482.

[0273] The downstream IMSA 483 in this embodiment can be described as a propeller and includes a first blade 484, a second blade 490, and a third blade 475. Each blade is rotatably connected to a rotor hub 493, with the axis of rotation substantially parallel to the long axis of the blade. The pitch angle of each rotor blade can be adjusted. The downstream IMSA 483 is configured to slow the fluid flow downstream of the downstream IMSA 483, i.e., reduce the magnitude of the fluid velocity relative to the inertial frame. The downstream IMSA 483 applies a downstream thrust at the IFMA configuration 470, as shown by thrust vector 494. A portion of the power extracted from the fluid by the downstream IMSA 483 is transferred to the upstream IMSA 471, and a portion of the transferred power is applied to the fluid by the upstream IMSA 471. As described above, this power can be transferred mechanically or electrically, for example.

[0274] The rotor system of IFMA Configuration 470 can be described as an IMSA assembly comprising upstream IMSA 471 and downstream IMSA 483. Figure 18 In the configuration shown, the power extracted by the IMSA component from the motion of the surrounding fluid (e.g., wind or water flow) is greater than that extracted by the equivalent baseline or reference configuration, where the influence of the upstream IMSA on the fluid is negligible, i.e., the thrust of the downstream IMSA in the baseline configuration is essentially equal to... Figure 18 The IFMA configuration shown has a net thrust of 470. In the baseline configuration, the IMSA component can be considered as containing only the downstream IMSA. For the depicted configuration, the baseline configuration is the same as that of a conventional wind turbine. The performance improvement is particularly significant at low wind or low flow rates.

[0275] Figure 19 This is a side view of another IFMA configuration 515. Figure 19 Some features of the device shown and some operating principles of the device are consistent with other accompanying drawings (especially...). Figure 7 The apparatus shown in ) is similar, therefore in Figure 19 The context will not describe it in detail, and vice versa.

[0276] The IFMA configuration 515 can also be described as a vessel having a hull 536, a superstructure 539 above the water surface 548, and a rudder 542 below the water surface.

[0277] The upstream IMSA 516 can be described as a propeller having at least a first propeller blade 517 and a second propeller blade 520. Each propeller blade is rotatably connected to a hub 523, with the axis of rotation parallel to the long axis of the blade. The pitch of each propeller blade can be adjusted according to the operating conditions of the vessel. The upstream IMSA 516 is supported by a fairing 525, which in some embodiments surrounds a drive shaft rigidly connected to the hub 523. In some embodiments, the hub 523 is connected to a generator in a direct-drive configuration. The upstream IMSA 516 is configured to slow the flow and reduce local free-flow flow on the hull 536. Therefore, the upstream IMSA 516 applies thrust to the IFMA configuration 515 in the direction of fluid flow relative to the hull 536, as indicated by thrust vector 524.

[0278] The downstream IMSA 526 can be described as a propeller having at least a first propeller blade 533 and a second propeller blade 530. Each propeller blade is rotatably connected to a hub, with the axis of rotation parallel to the long axis of the blade. The pitch of each propeller blade can be adjusted according to the operating conditions of the vessel. The downstream IMSA 526 is supported by a fairing 535, which in some embodiments surrounds a drive shaft rigidly connected to the hub. In some embodiments, the hub is connected to an electric motor in a direct-drive configuration. The downstream IMSA 526 is configured to accelerate flow. Therefore, the downstream IMSA 526 applies thrust to the IFMA configuration 515 in the direction opposite to the fluid flow relative to the hull 536, as indicated by thrust vector 534.

[0279] The upstream IMSA 516 can reduce the drag of the IFMA configuration 515. This drag reduction can include a reduction in the viscous drag of the hull 536 and / or a reduction in the gravity wave drag of the hull 536. The drag reduction is associated with altering the spatial distribution of fluid velocity relative to the hull 536 via the upstream IMSA 516. Reducing the magnitude of the local free-flow fluid velocity of the hull 536, reducing the fluid velocity at and relative to the wetted surface of the hull 536, and generating a more favorable velocity distribution near the wetted surface of the hull 536 via the upstream IMSA 516 can contribute to the reduction of viscous drag. For example, a more favorable velocity distribution can include a reduced peak spatial fluid velocity gradient or a reduced spatial average magnitude of the spatial fluid velocity gradient near the IFMA configuration 515. The reduction in wave drag can result from a smoother change in the direction of fluid flow as the fluid flows around the IFMA configuration 515, or from a smoother displacement of the fluid by the IFMA configuration 515 due to the deceleration of the fluid flow by the upstream IMSA 516 and the acceleration of the fluid flow by the IMSA 526. Therefore, the intensity of the disturbance to the fluid flow by the IFMA configuration 515 can be reduced. In some embodiments, for example, the upstream IMSA 516 can be configured to perform a function similar to that of a spherical bow found in conventional hull designs.

[0280] Figure 20 This is a side view of another IFMA configuration 560. Figure 20 Some features of the device shown and some operating principles of the device are consistent with other accompanying drawings (especially...). Figure 7 The apparatus shown in ) is similar, therefore in Figure 20 The context will not describe it in detail, and vice versa.

[0281] The IFMA configuration 560 can also be described as a train or truck, and includes a first car 61, a second car 576, a third car 577, a fourth car 589, and a fifth car 591. Each car is supported by wheels (such as wheels 563), which facilitate movement of the car relative to the road or track 605. Each car is connected to an adjacent car via connectors (such as connectors 566). The cars are rotatably connected to the wheels via support structures (such as support structures 578).

[0282] The upstream IMSA 567 can be described as a propeller having at least a first propeller blade 568 and a second propeller blade 571. Each propeller blade is rotatably connected to a hub 574, with rotation parallel to the long axis of the blade. The pitch of each propeller blade can be adjusted according to the operating conditions of the aircraft. The upstream IMSA 567 is configured to slow down the flow and reduce the local free flow of the remaining aircraft. Therefore, the upstream IMSA 567 applies thrust to the IFMA configuration 560, directed in the direction of fluid flow relative to the IFMA configuration 560, as indicated by thrust vector 575.

[0283] The downstream IMSA 596 can be described as a propeller. In the IFMA configuration 560, the first carriage 561 can be the same as the fifth carriage 591 to reduce the manufacturing cost of embodiment 560. It should be noted that the first carriage 561 operates in a different manner than the fifth carriage 591. The downstream IMSA 596 is configured to accelerate the flow. Therefore, the downstream IMSA 596 applies thrust to the IFMA configuration 560 in the opposite direction of the fluid flow relative to embodiment 560, as shown by thrust vector 604.

[0284] Due to the length of the IFMA configuration 560, the drag reduction effect of the upstream IMSA 574 decreases as the distance from the upstream IMSA 574 along the length of embodiment 560 increases. This could be due to viscous effects, for example. The intermediate IMSA 580 is configured to correct for any distortions in the actual velocity distribution compared to an ideal velocity distribution near the outer surface of the IFMA configuration 560. The intermediate IMSA 580 includes at least a first propeller blade 581 and a second propeller blade 584. Each propeller blade is rotatably connected to a hub 587, with the axis of rotation parallel to the long axis of the blade. The pitch of each propeller blade can be adjusted according to the operating conditions of the aircraft. The intermediate IMSA 580 is configured to slow the flow and reduce local free-flow in the remaining aircraft. Therefore, the intermediate IMSA 580 applies thrust to the IFMA configuration 560 in the direction of fluid flow relative to embodiment 560, as indicated by thrust vector 588.

[0285] In some embodiments, the sum of the drag acting on the aircraft portion between the intermediate IMSA 580 and the downstream IMSA 596 and the thrust or drag acting on the intermediate IMSA 580 is less than the drag acting between the third and last cars in this embodiment without an intermediate IMSA (i.e., in the case where the third car is configured in a manner similar to the second car 576). For some embodiments, for some operating conditions, the net traction drag acting on embodiments without a dedicated intermediate IMSA (such as intermediate IMSA 580) is greater than the net traction drag acting on the IFMA configuration 560. It should be noted that some embodiments may include several intermediate IMSAs configured in a manner similar to intermediate IMSA 580. It should be noted that several cars (such as car 576) may be located between upstream IMSAs, intermediate IMSAs, or downstream IMSAs. In some embodiments, the connection between adjacent cars includes an aerodynamic fairing configured to allow the cars to rotate relative to each other during curves or bends in a road or track.

[0286] The upstream IMSA 567 and intermediate IMSA 580 can be configured to extract energy from the surrounding fluid, while the downstream IMSA 596 can be configured to apply at least a portion of the extracted energy to the fluid surrounding the IFMA configuration 560. It should be noted that embodiments similar to the IFMA configuration 560 may include a separate traction motor, which is configured to facilitate propulsion of the embodiment by transmitting torque to at least one wheel. In other embodiments, any unresolved thrust requirements of the embodiment are provided by the downstream IMSA 596.

[0287] Figure 21 This is a side view of another IFMA configuration 620. Figure 21 Some features of the device shown and some operating principles of the device are consistent with other accompanying drawings (especially...). Figure 7 and Figure 20 The apparatus shown in ) is similar, therefore in Figure 21 The context will not describe it in detail, and vice versa.

[0288] The IFMA configuration 620 can also be described as a train or truck, and includes a first car 621, a second car 632, a third car 633, a fourth car 634, a fifth car 646, and a sixth car 647. Each car is supported by wheels (such as wheels 623), which facilitate movement of the car relative to a road or track 657. Each car is connected to adjacent cars via connectors (such as connectors 626). The cars are rotatably connected to the wheels via support structures.

[0289] The upstream IMSA 627 can be described as a ducted fan comprising a duct 628 surrounding a propeller having at least a first propeller blade and a second propeller blade. Each propeller blade is rotatably connected to a hub, with the axis of rotation parallel to the long axis of the blade. The pitch of each propeller blade can be adjusted according to the operating conditions of the aircraft. The upstream IMSA 627 is configured to slow the flow and reduce the local free flow of the remaining aircraft. Therefore, the upstream IMSA 627 applies thrust to embodiment 620 in a direction relative to the fluid flow, as indicated by thrust vector 631.

[0290] The downstream IMSA 652 can be described as a ducted fan. In the IFMA configuration 620, the first compartment 621 is identical to the sixth compartment 647 to reduce the manufacturing cost of embodiment 620. It should be noted that the first compartment 621 operates in a different manner than the sixth compartment 647. The downstream IMSA 652 is configured to accelerate the flow. Therefore, the downstream IMSA 652 applies a thrust to embodiment 620 directed in the opposite direction of the fluid flow relative to embodiment 620, as shown by thrust vector 656.

[0291] IFMA configuration 620 may include an intermediate IMSA, similar to embodiment 560. In IFMA configuration 620, the intermediate IMSA is implemented by two cars (i.e., third car 633 and fourth car 634) instead of one car. Both cars are identical to the sixth car 647 or the first car 621 to reduce the manufacturing cost of embodiment 620. In this embodiment, the ducted fan 634 of the third car 633 is feathered. The ducted fan 640 of the fourth car 634 is... Figure 20 The intermediate IMSA 580 is configured in a similar manner. Therefore, the IMSA 640 applies a thrust to embodiment 620 in the direction of fluid flow relative to embodiment 620, as shown by thrust vector 644.

[0292] Upstream IMSA can reduce the drag of IFMA configuration 560 or 620. This drag reduction can include a reduction in the viscous drag of the carriage. The drag reduction is associated with altering the spatial distribution of fluid velocity relative to and near IFMA configuration 560 or 620 through upstream IMSA. This alteration can refer to reducing the average magnitude of the spatial velocity gradient of the fluid flow. For example, the configurations of upstream and downstream IMSA can be mathematically optimized to minimize the total power consumption of IFMA configuration 560 or 620 constrained by constraints such as structural or economic limitations.

[0293] Figure 22This is a cross-sectional view of a catheter device 700 according to some embodiments. Some features of the device shown in FIG1 and some operating principles of the device are similar to those of devices shown in other figures, and therefore will not be repeated. Figure 22 The same details are described in the context of the other, and vice versa.

[0294] The conduit assembly 700 may surround the fuselage assembly 719. As shown, the conduit assembly 700 has a circular cross-section when viewed along the X-axis and is axially symmetrical about an axis parallel to the X-axis. The conduit assembly 700 is an embodiment of IMCA. The conduit assembly 700 may include an outer surface 717 and a channel 703, the inner surface 718 of which is located between a first opening 704 and a second opening 712, wherein the channel may be formed to include a first contraction 705, a first expansion 706, a region with a substantially constant cross-sectional area when viewed in the X direction, a second expansion 708, a second contraction 710, and a third expansion 711. It should be noted that the terms "contraction" and "expansion" refer to the relative sizes of the radii of the axially symmetrical channel.

[0295] The conduit assembly 700 may include a first compartment 730 and a second compartment 732. These compartments can be used for a variety of purposes. In some embodiments, they may be used to secure components of landing gear, fuel, cargo, or other lifting or thrust mechanisms.

[0296] It should be noted that the channel radius or geometry can be changed in different ways as a function of position along the X-axis, or configured differently for other embodiments or other operating conditions. In some embodiments, the third expansion portion 711 is not required, i.e., the second opening can be located at the end of the second contraction portion 710. In some embodiments, the cross-sectional geometry of the channel 703 or the outer surface 717 can be square, rectangular, or elliptical. In some embodiments, the cross-sectional geometry of the channel 703 can, for example, change from a square to a circle in the positive X direction.

[0297] In some embodiments, the cross-sectional area of ​​the circular or annular channel 703 can vary over time. For example, the radius of the channel at station 739 can be changed for different operating conditions. The radius can be increased or decreased depending on the magnitude of the free-flow velocity. In this way, the characteristics of the flow through the conduit 703 can be altered and controlled, allowing the principles of the invention to be applied to different free-flow conditions. For example, the presence or location of shock waves within the first expansion portion 706 or the second expansion portion 708 can be adjusted by controlling the cross-sectional area of ​​the channel 703 at station 739. Various methods can be used to change the cross-sectional area of ​​the channel as a function of time. For example, a ramp connected to the conduit assembly 700 can be hydraulically extended into the channel, thereby reducing the cross-sectional area of ​​the channel. In another example, a spike located within the channel 703 can be moved axially along the length of the channel, i.e., along the X direction, toward or away from the contraction of the channel, thereby reducing or increasing the annular cross-sectional area of ​​the channel 703, respectively.

[0298] The conduit device 700 may be constructed from bulk material 70, which may include metal alloys such as aluminum, steel, or titanium. In some embodiments, bulk material 701 comprises composite materials such as carbon fiber or glass fiber.

[0299] In some embodiments, the fuselage assembly 719 includes a leading edge point 720, a trailing edge point 721, an inner surface 723, and an outer surface 722. In some embodiments, a first fuselage compartment 724 is separated from a second fuselage compartment 725 by a partition 728. The fuselage assembly 719 may be rigidly connected to the duct assembly 700 by one or more support rods (such as support rods 727). In some embodiments, the support rods may reduce the cross-sectional area of ​​the channel 703 at the location of the support rods by only a small amount. In some embodiments, the fuselage may be configured to carry, for example, cargo, passengers, or fuel.

[0300] As previously defined, embodiments of the invention are at least partially surrounded by a fluid. It should be noted that different types of fluids can simultaneously surround at least a portion of embodiments of the invention. For example, embodiments such as those involving a ship traversing water can be surrounded by both water and air (i.e., liquid and gaseous fluids). Figure 22 In this context, fluids are compressible. For example, a fluid can be a gas such as air.

[0301] Figure 22The operating conditions shown may include nominal horizontal cruise operating conditions. In the simplified case shown, the free flow relative to the center of mass of the duct device 700 is constant in time and spatially uniform in magnitude and direction, with the direction parallel to the X-axis. Under the operating conditions shown, the magnitude of the free flow velocity relative to the duct device 700 is greater than the speed of sound in the fluid. Since wind speed is assumed to be negligible in this case, this is equivalent to the duct device 700 moving relative to the fluid at a speed faster than the speed of sound in the fluid in an inertial frame of reference. Figure 22 In the middle, the free flow velocity relative to the conduit device 700 is aligned with and parallel to the X-axis, that is, from the left side of the page to the right side of the page.

[0302] Dashed lines 715 and 716 indicate stagnant streamlines that are incident on the leading edge of the conduit assembly 700 or begin at the trailing edge of the conduit assembly 700. Therefore, streamlines 715 and 716 are part of a flow surface or flow tube that separates the fluid flowing around the conduit assembly 700 from the fluid flowing in the channel 703 of the conduit assembly 700. In this embodiment, the flow tube is circular when viewed along the X direction.

[0303] The fluid upstream of the conduit assembly 700 (e.g., at station 734) moves faster relative to the conduit assembly 700 than... Figure 22 The speed of sound in the fluid in the illustrated configuration. The first contraction 705, the first expansion 706, and the second expansion 708 of channel 703 are configured to compress the fluid flowing through channel 703 in the positive X direction. A first throat is defined as a portion of channel 703, having the minimum cross-sectional area of ​​channel 703 between the first contraction 710 and the first expansion 711 when viewed along the X direction. The average velocity of the fluid relative to the conduit assembly 700 at the first throat (i.e., station 735) is approximately equal to the speed of sound in the fluid at that location. In this embodiment, upstream, such as at station 734, the average relative velocity is greater than the speed of sound, while downstream, such as at stations 737 or 738, the average relative velocity is less than the speed of sound in the fluid. In the illustrated embodiment, the flow through channel 703 is substantially adiabatic and isentropic when friction is neglected. In other embodiments, shock waves may be present between the first throat and station 738. In other words, the relative velocity of the fluid downstream of the first throat can be faster than the speed of sound in the fluid, wherein the relative velocity decreases to a speed slower than the speed of sound throughout the shock wave, thereby generating a relative velocity slower than the speed of sound at station 738, such as in the ideal case where there is an infinitely weak impact at the first throat.

[0304] Both the second contraction 710 and the third expansion 711 of channel 703 are configured to expand the fluid flowing in channel 703 in the positive X direction. A second throat is defined as a portion of channel 703, having the minimum cross-sectional area of ​​channel 703 between the second contraction 710 and the third expansion 711 when viewed along the X direction. The average velocity of the fluid relative to the conduit assembly 700 at the second throat (i.e., station 739) is approximately equal to the speed of sound in the fluid at that location. In this embodiment, upstream, such as at station 738, the average relative velocity is less than the speed of sound, while downstream, such as at station 740, the average relative velocity is greater than the speed of sound in the fluid.

[0305] It should be noted that in other embodiments, the fuselage, such as fuselage assembly 719, may be incorporated into the conduit assembly. For example, such embodiments do not need to feature a centrally located fuselage, such as fuselage assembly 719, but may be located within an annular volume. For example, the first compartment 730 or the second compartment 732 may be considered and configured as the fuselage. In another instance, the axially symmetrical fuselage assembly 719 does not need to be arranged concentrically with the axially symmetrical conduit assembly 700. In other words, the central axis of the fuselage assembly 719 need not coincide with the central axis of the conduit assembly 700. For example, the fuselage assembly may be arranged flush with the inner surface 718 of the conduit assembly 700, similar to the first compartment 730, rather than being located at the center within the channel 703 as shown in 22. In this case, the outer surface 722 of the fuselage is the same as the inner surface 718 of the channel 703, and the channel 703 only passes through the center of the fuselage. Figure 22 Compared to the configuration of the illustrated embodiment, this can reduce the wetting area and viscous resistance. In some embodiments, the first compartment 730 can be considered connected to the second compartment 732 in a similar manner to the first compartment 730 via an annular body section embedded within the conduit assembly 700. In some embodiments, the first compartment 730 and the second compartment 732 can be considered congruent. It should be noted that when viewed along the X direction, the angle formed by the cross-section of the body relative to the central axis of the conduit assembly 700 need not be 360 ​​degrees as in the circumferential case exemplified by the annular first compartment 730, but can be, for example, 200 degrees, or 100 degrees, or 60 degrees. In other embodiments, when viewed along the X direction, the cross-section of the body assembly 719 can be elliptical or rectangular.

[0306] Disturbances moving through a fluid at speeds greater than the wave velocity typically induce wave drag. Wave drag is a measure of the wave energy generated by the disturbance. There are several methods to quantify wave drag. For example, wave drag can be calculated by dividing the wave power generated by a particular disturbance by the mean free-flow velocity.

[0307] Disturbances can be caused by a volume configured to displace the fluid. This volume could be the hull of a ship that generates gravity waves, or the fuselage or wing of a supersonic aircraft that generates shock waves. Disturbances can also be caused by devices configured to alter the fluid flow characteristics at a specified location, where such alterations could include, for example, changes in flow direction, changes in the magnitude of flow velocity in inertial space, or changes in fluid temperature. Such devices could be, for example, electric or magnetic field generators or lasers. Surface discontinuities can also disturb adjacent flow fields. Disturbances can cause fluid flow to shift, thereby generating shock waves in the air or surface gravity waves in the water.

[0308] According to some embodiments of the present invention, conduit devices can be used to manipulate fluid flow near disturbances in a manner that reduces wave drag associated with disturbances.

[0309] For example, in embodiments involving travel through incompressible fluids such as water, the resistance due to surface waves can be reduced by using a conduit assembly configured as follows: After entering the conduit assembly through the inlet, the fluid is accelerated through a first contraction, wherein in some embodiments, the first contraction can be configured in a manner similar to a first contraction 705, and the inlet can be configured in a manner similar to a first opening 704. It should be noted that, in this case, the acceleration of the fluid in the first contraction is similar to that in… Figure 22 In the illustrated embodiments, the fluid deceleration is reversed. In some embodiments, after being accelerated in the first contraction, the fluid flows through a cross-section having a substantially constant cross-sectional area. For example, the fluid may flow through a pipe or channel with a circular cross-section. In other embodiments, the pipe has an annular cross-sectional area, such as in... Figure 22The annular portion of channel 703 at station 737. For a given cross-sectional area, a circular cross-section may be more advantageous than an annular cross-section as the wetting area decreases. In some embodiments, the conduit is substantially straight. In some embodiments, the conduit includes curves or bends. For example, the conduit may guide fluid flow around the cargo hold of a container ship. After a cross-section having a substantially constant cross-section, the fluid flow then enters a first expansion section, where the fluid is slowed before flowing out through an outlet or a second opening. In some embodiments, the velocity of the fluid leaving the outlet is substantially equal to the free flow velocity. In some embodiments, the outlet velocity may be greater than or less than the free flow velocity. In the case of the conduit device used on a ship, the leading edge of the conduit device forms the bow, and the outer surface of the conduit device, such as the outer surface 717 of the conduit device 700, forms the outer hull of the ship, and the trailing edge of the conduit device forms the stern. The volume within the outer surface of the conduit device not occupied by the fluid flowing through the channel (including the first contraction section, the conduit with a substantially constant cross-sectional area, and the first expansion section) can be considered as the effective volume of the ship, which may, for example, contain a cargo hold or passenger compartment. When viewed in the direction of flow, the conduit device may have a circular cross-section. In other embodiments, the conduit device may have a semi-circular cross-section similar to that of a conventional ship's hull. To reduce wave drag associated with gravity waves in the water, only a portion of the ship in contact with the water may be surrounded, embedded in, or configured as the conduit device.

[0310] During nominal operation, the conduit device can be configured to reduce wave drag associated with the effective volume movement or other disturbances via fluid. The fluid interacting with the conduit device can be distinguished as fluid flowing through internal channels of the conduit device (referred to as "internal fluid") and fluid flowing around the conduit device on one side of its outer surface that does not flow through internal channels (referred to as "external flow"). The conduit device is configured to reduce disturbances imposed on the external flow. In this embodiment, this is achieved by an outer surface parallel to the free flow. For example, the outer surface of the conduit device 700 is cylindrical and parallel to the free flow. This reduces disturbances imposed by the outer surface. In some embodiments, the circular cross-section of the outer surface of the conduit device along the flow direction may, for example, have a reduced diameter in the downstream direction. This can reduce boundary layer disturbances on the portion of the external flow located outside the boundary layer on the outer surface. In some embodiments, the wave drag associated with the outer surface of the conduit device is negligible when friction is ignored.

[0311] The conduit device can also be configured to reduce wave drag associated with the internal flow. In some embodiments, during nominal operation, the cross-sectional area and shape of the flow tube associated with the internal flow upstream of the inlet are substantially equal to the cross-sectional area and shape of the inlet. In other embodiments, the cross-sectional area of ​​the former may be greater than or less than that of the latter. For example, in other embodiments, the shape of the cross-sectional area of ​​the former may be greater than that of the latter. Since the objective may be to minimize total drag, not just wave drag, some embodiments may have reduced but non-zero wave drag compared to embodiments in the prior art. In some embodiments, during nominal operation, the cross-sectional area and shape of the flow tube associated with the internal flow downstream of the outlet are substantially equal to the cross-sectional area and shape of the outlet. For example, in other embodiments, the cross-sectional area of ​​the former may be greater than that of the latter. In other embodiments, the shape of the cross-sectional area of ​​the former may be greater than that of the latter. In some embodiments, disturbances applied to the internal flow produce negligible disturbances or negligible wave drag on the external flow. In some embodiments, the wave drag imposed on the external flow by disturbances in the internal flow is reduced compared to embodiments in the prior art. Generally speaking, the magnitude of the disturbance exerted on the fluid due to the initial deflection around a finite volume, such as the disturbance exerted in the first contraction, can be reduced by controlling the disturbance within the conduit device until it can be eliminated or mitigated by a second disturbance, such as the disturbance exerted by the first expansion before the second opening of the conduit device.

[0312] In some embodiments, the propulsion unit is located within the channel of the conduit assembly, wherein the propulsion unit may include at least one propeller configured to accelerate fluid, similar to a marine pump jet propeller. For example, the propeller may be located in a first contraction section, with the propeller thrust directed upstream. In some embodiments, the propeller may be used to reduce or avoid localized pressure increases near the inner wall of the first contraction section and ensure uniform flow within the first contraction section. The first contraction section is configured to accelerate the fluid within it in a manner that reduces the wave drag of the conduit assembly compared to other configurations. To this end, the variation in fluid velocity magnitude for a given cross-sectional area of ​​the first contraction section can be reduced when viewed in a direction parallel to the free flow, i.e., in the flow direction. This can be achieved, for example, by the propulsion unit or an annular foil located within the first contraction section. Such fluid flow manipulation devices can ensure that a reduction in the cross-sectional area of ​​the first contraction section is accompanied by a corresponding increase in the fluid velocity magnitude and a corresponding decrease in the fluid pressure within the first contraction section. A first expansion section can be configured in a similar manner.

[0313] In some embodiments, a propeller may be located in a first expansion section, wherein the propeller thrust is directed downstream, and wherein at least a portion of the energy extracted from the fluid is mechanically or electrically recovered and stored for later use or for useful work, such as powering an upstream propeller in a first contraction section. The propeller in the expansion section can be used to regulate the fluid flow rate through the channel. Such a propeller can also be used to avoid or reduce flow separation in the first expansion section, which can reduce the length of the expansion section along the flow direction. In other embodiments, an annular foil or conduit may be placed within the expansion section to avoid or reduce resistance due to flow separation. In some embodiments, a propulsion unit may be placed between the first expansion section and the first contraction section. For example, such a propulsion unit can be used to at least counteract a reduction in fluid flow rate through the conduit device due to friction.

[0314] In another example, for a disturbance traveling through a compressible fluid at a velocity greater than the wave velocity in the fluid, it can be addressed by, for example... Figure 22 The conduit device shown is configured to reduce wave drag associated with disturbances. For example, although the principles of the invention can be applied to other types of waves, the wave discussed can be a sound wave or a shock wave. In such embodiments, the conduit device can be configured to artificially reduce the fluid velocity near the disturbance. Figure 22 In this context, the disturbance discussed can be considered as the fuselage 719, although the ducting device itself also introduces disturbances to the fluid flow. In the case of the ducting device, at least some disturbances, such as those associated with deflecting, slowing, or accelerating the fluid, are configured to cancel each other out or be canceled out near the ducting device. In this particular embodiment, some disturbances associated with the fuselage device 719, such as those associated with deflecting, slowing, or accelerating the fluid, are also configured to cancel each other out or be canceled out near the ducting device. In other embodiments, it is not necessary to eliminate at least one type of disturbance introduced into the fluid by the fuselage device, but it may manifest itself in the far wake downstream of both the ducting device and the fuselage device, such as... Figure 24 As discussed in the context of the illustrated embodiments.

[0315] exist Figure 22In this embodiment, assuming zero viscous resistance, the flow outside the flow tube 715 is not disturbed. This is due to the cylindrical outer surface 717 parallel to the free flow. Therefore, the flow near the outer surface 717 is deflected by only a minimal amount. For example, this deflection can be attributed to the boundary layer associated with the outer surface 717. In other embodiments, the external flow may experience localized disturbances. The outer surface of the conduit device need not be parallel to the free flow velocity. For example, the cross-sectional area of ​​the outer surface along the flow direction can increase or decrease in the downstream direction. For example, the external flow can be deflected slightly in a radially outward direction. In some embodiments, the deflection can be in a radially inward direction. The conduit device can be configured in such a way that the total resistance associated with the motion of the embodiment relative to the fluid is minimized. In addition to configuring the outer surface of the conduit device to reduce the disturbance exerted on the external flow by said surface, the dimensions and shapes of the upstream flow tube 715 and the downstream flow tube 716 of the conduit device are also configured to remain unchanged under an idealized frictionless condition. In other words, any disturbances caused by the conduit device are not transmitted to the external flow in the form of changes in the shape or size of the flow tube, resulting in negligible wave drag associated with the conduit device in the external flow. The uniform cylindrical shape of the flow tube 715 upstream of the conduit device is a result of the conduit device traveling faster than the wave velocity in the fluid, and the geometry of the conduit device being configured to prevent the formation of bow-shaped impacts during nominal operation.

[0316] As discussed in previous examples, at least a portion of the disturbance to the internal flow applied at the inlet of the conduit assembly 700, namely the compression of the fluid in the first contraction 705 and the first expansion 706, is configured to be contained within the conduit assembly 700, such as in a region 707 or a second expansion 708 having a substantially constant cross-sectional area, until they are canceled out at the outlet, namely, the expansion of the fluid in the second contraction 710 and the third expansion 711. For simplicity, when assuming inviscid flow, the compression within the first contraction 705 is configured to be isentropic and adiabatic. This can be achieved by gradually compressing the fluid flowing through the first contraction 705. The respective compressibility characteristics generated by the elements of the inner surface 718 within the first contraction 705 are combined with the corresponding characteristics of the circumferentially adjacent elements, and then the compressibility characteristics generated by the adjacent elements flowing downstream can be combined, integrated, or overtaken by the upstream characteristics to form a shock wave. In such embodiments, the first contraction 705 can be considered as a sector containing an infinitely weak compressive shock wave. In other embodiments, a shock wave of finite size can be formed within the first contraction 705. For example, this could be a result of a more realistic finite leading edge angle of the first inner surface 718 at the first opening 704. When wall friction and heat transfer effects are neglected, it can also be assumed that the expansion through the second contraction 710 and the third expansion 711 is isentropic and adiabatic. The fluid velocities at the second opening 712 and the first opening 704 are spatially uniform in magnitude and direction, and... Figure 22 The simplified ideal case shown is equal to the free flow velocity vector.

[0317] Because the fluid velocity is reduced to subsonic before encountering the fuselage assembly 719, in the simplified embodiment shown, there is no shock wave generated by the fuselage assembly 719 within the duct assembly 700. In other embodiments, shock waves may form within the channel 703. For example, this could be due to localized transonic flow. For example, around an IMSA (such as...) Figure 24The fluid flow in the IMSA 817 can locally reach supersonic speeds. For example, the IMSA 817 can be a transonic airfoil. In another example, the shock wave can also be located within the first expansion 706, as mentioned. This avoids the failure of flow through the channel 703 to begin due to changes in free flow, thus preventing bow-shaped impacts. For example, such changes could be caused by wind in the atmosphere. In another example, the flow velocity within the channel can be supersonic throughout the channel or near the disturbance generating device. In such embodiments, shock waves will form within the channel. At least a portion of these shock waves can be configured to cancel each other out, similar to the shock waves in a Bussmann biplane. In configurations where these shock waves are not canceled out, the wave drag associated with the disturbance generating device within the channel of the duct device or near the fluid control device configured according to the invention, and the combined wave drag associated with the disturbance generating device and the fluid control device, can, however, be lower than the wave drag associated with an equivalent disturbance generating device for which no change in fluid flow is made by the fluid control device configured according to the invention. By reducing the local free-flow of the disturbance generation device relative to the free-flow, the wave drag of the disturbance generation device can be reduced even when the local free-flow is still supersonic.

[0318] It should be noted that the movement of a body such as fuselage 719 through a fluid such as air at supersonic speeds will generate shock waves. However, the wave drag associated with fuselage 719 can be reduced due to the manipulation of the fluid flow via duct device 700. The combined wave drag of duct device 700 and fuselage device 719 can be lower than the theoretical wave drag of fuselage 719 alone, i.e., in the “reference case,” without being included in or embedded in a fluid manipulation device (such as duct device 700) configured according to the invention. In other embodiments, such as Figure 24 As shown, different types of disturbance generating devices can be positioned at the location of the body assembly 719, i.e., replacing the body assembly 719. In some embodiments, the total resistance of the combined assembly can be lower than the theoretical total resistance of the disturbance generating devices or only a suitable equivalent amount traveling in the fluid, i.e., in the reference case. For example, the reduction in wave resistance can be greater than the increase in viscous resistance associated with the additional conduit assembly. In other embodiments, the total resistance can be greater than the total resistance in the reference case. For example, this can be attributed to the increased viscous resistance associated with the increased or enlarged wetting area combined with the conduit assembly and the body assembly. In some such embodiments, the benefits gained from the reduction in noise associated with the waves generated by the disturbance generating devices can still offset any cost increase associated with the increase in total resistance. It should be noted that a reduction in the fluid velocity within channel 703 can also help reduce the viscous resistance of the conduit assembly 700.

[0319] The purpose of the duct device 700 can be considered in part as the deceleration and pressure increase of the compressible fluid near any disturbance generating device (in this case, the fuselage device 719) in order to reduce the wave drag associated with the disturbance generating device. The disturbance generating device may also include, for example, a propeller, a fan of a turbofan engine, a wing, a horizontal or vertical control surface, or a type of IMCA or IMSA.

[0320] exist Figure 22 In this embodiment, the body assembly 719 is shown as a structure connected to the conduit assembly 700 but easily distinguishable from it. In other embodiments, the body may be embedded within the conduit assembly 700 in such a way that the body is contained within the inner surface 718 and outer surface 717 of the conduit assembly 700. In some such embodiments, similar to the first compartment 730 or the second compartment 732, the body is configured in an annular, cylindrical manner. In other words, the channel 703 may be configured to pass through the center of the body, while the outer surface of the body is the same as the outer surface 717 of the conduit assembly 700. In other embodiments, such as Figure 22 As shown, the fuselage does not need to completely surround the channel 703, and the channel 703 does not need to completely surround the fuselage. For example, the channel can have a circular cross-section along the flow direction, partly defined by the fuselage portion of the ducting device and partly defined by the outer wall of the ducting device. Instead of an annular cross-section, the fuselage can be semi-circular or semi-annular in the cross-section along the flow direction. The circumferential extent of the fuselage or the angle formed by the fuselage around the central axis of the cylindrical ducting device does not need to be 360 ​​degrees as in the annular or circular case, but can be, for example, 300 degrees, 200 degrees, 100 degrees, or 60 degrees. In other words, the fuselage can be configured as a continuous volume, i.e., a volume that does not completely surround the channel 703, and the channel can be circular or semi-circular in shape. It should be noted that, with such as Figure 22 Compared to the annular channel shown, a channel with a closed shape (such as a closed circular cross-sectional shape) can be used to reduce the wetting area of ​​the conduit device.

[0321] Figure 24 This is a cross-sectional view of another embodiment of the present invention. Figure 24 Some features and operating principles of the embodiments shown are similar to those described in other accompanying drawings, and therefore will not be repeated. Figure 24 The same detailed description is given in the context of the text, and vice versa.

[0322] It should be noted that the device contained within the inner surface 816 and the outer surface 815 need not be a solid material, but may include open spaces to avoid unnecessarily increasing the mass or cost of the catheter device 800. For example, the catheter device 800 may contain a material similar to Figure 22 The first compartment 730 or the second compartment 732 shown.

[0323] The catheter device 800 surrounds the IMSA 817. In the illustrated embodiment, the catheter device 800 has a circular cross-section when viewed along the X-axis and is axially symmetrical about an axis parallel to the X-axis. The catheter device 800 can be considered as an IMCA. The catheter device 800 includes an outer surface 815 and a channel 803 having an inner surface 816 located between a first opening 804 and a second opening 810, wherein the channel may include a first contraction 805, a first expansion 806, a region of substantially constant cross-sectional area 807 of the channel 803 when viewed in the X direction, a second contraction 808, and a second expansion 809. It should be noted that the terms "contraction" and "expansion" refer to the size of the radius of the axially symmetrical channel.

[0324] In some embodiments, the cross-sectional area of ​​channel 803 is elliptical or rectangular. In some such embodiments, the major axis of the shape is parallel to the Z-axis during nominal operation. Such conduit devices can be configured to receive or surround and manipulate local free-flow of a wing with a major axis that is also parallel to the Z-axis.

[0325] The conduit device 800 may be constructed from bulk material 801, which may include metal alloys such as aluminum, steel, or titanium. In some embodiments, bulk material 801 includes composite materials, such as carbon fiber or glass fiber.

[0326] The IMSA 817 can be formed into the shape of an aircraft wing. Figure 24 The cross-sectional view shows the airfoil profile of IMSA 817 with trailing edge 819 and outer surface 820. IMSA 817 can be rigidly connected to the duct assembly via support rod 824. The stagnant streamlines of IMSA 817, namely the streamlines incident on the leading edge stagnant point of the right wingtip of IMSA 817 and the streamlines originating from the trailing edge stagnant point of the right wingtip of IMSA 817, are indicated by dashed line 841. The lift vector of IMSA 817 has a fundamental component parallel to the Y-axis. It should be noted that, for clarity, the shape and dimensions of wing 817 are shown in an enlarged manner, not as a scale representation or actual wing.

[0327] As previously defined, embodiments of the invention are at least partially surrounded by fluid. Figure 23 In this context, fluids are compressible. For example, a fluid can be a gas such as air.

[0328] exist Figure 23The operating conditions shown may include nominal horizontal cruise operating conditions. In the simplified case shown, the free flow relative to the center of mass of the duct device 800 is constant in time and spatially uniform in magnitude and direction, with the direction parallel to the X-axis. Under the operating conditions shown, the magnitude of the free flow velocity relative to the duct device 800 is greater than the speed of sound in the fluid. Since wind speed is assumed to be negligible in this case, this is equivalent to the duct device 700 moving relative to the fluid at a speed faster than the speed of sound in a stationary fluid in an inertial frame of reference. Figure 23 In the middle, the free flow velocity relative to the conduit device 800 is aligned with and parallel to the X-axis, that is, from the left side of the page to the right side of the page.

[0329] Dashed lines 813 and 814 indicate stagnant streamlines that are incident on the leading edge of the conduit assembly 800 or begin at the trailing edge of the conduit assembly 800. Therefore, streamlines 813 and 814 are part of a flow surface or flow tube that separates the fluid flowing around the conduit assembly 800 from the fluid flowing in the channel 803 of the conduit assembly 800. In this embodiment, the flow tube is circular when viewed along the X direction.

[0330] The fluid upstream of the conduit assembly 800 (such as at station 834) moves faster relative to the conduit assembly 800 than... Figure 23 The speed of sound in the fluid is shown in the configuration. The first contraction 805 and the first expansion 806 of channel 803 are configured to compress the fluid flowing through channel 803 in the positive X direction. A first throat is defined as a portion of channel 803, having the minimum cross-sectional area of ​​channel 803 between the first contraction 805 and the first expansion 806 when viewed along the X direction. The average velocity of the fluid relative to the conduit assembly 800 at the first throat (i.e., station 835) is approximately equal to the speed of sound in the fluid at that location. In this embodiment, upstream, such as at station 834, the average relative velocity is greater than the speed of sound, while downstream, such as at station 837, the average relative velocity is less than the speed of sound in the fluid. In the illustrated embodiment, the flow through channel 803 is substantially adiabatic and isentropic when friction is neglected. In other embodiments, shock waves may be present between the first throat and station 837. In other words, the relative velocity of the fluid downstream of the first throat can be faster than the speed of sound in the fluid, where the relative velocity decreases to a speed slower than the speed of sound throughout the shock wave, thus generating a relative velocity slower than the speed of sound at station 837, such as in the ideal case where there is an infinitely weak impact at the first throat.

[0331] Both the second contraction 808 and the second expansion 809 of channel 803 are configured to expand the fluid flowing through channel 803 in the positive X direction. A second throat is defined as a portion of channel 803 having the minimum cross-sectional area of ​​channel 803 between the second contraction 808 and the second expansion 809 when viewed along the X direction. The average velocity of the fluid relative to the conduit assembly 800 at the second throat (i.e., station 839) is approximately equal to the speed of sound in the fluid at that location. In this embodiment, upstream, such as at station 837, the average relative velocity is less than the speed of sound, while downstream, such as at station 840, the average relative velocity is greater than the speed of sound in the fluid.

[0332] The conduit device 800 is configured to slow the fluid flow near the disturbance generating device (in this case, which can be considered as IMSA 817), such that the local free-flow of IMSA 817 is less than the magnitude of the free-flow velocity. As a result of the conduit device, the wave drag associated with IMSA 817 is reduced compared to the reference case, where the local free-flow of IMSA 817, or an equivalent IMSA, or the lifting device, is substantially equal to the free-flow. It should be noted that the local free-flow can still be faster than the wave velocity within the fluid. In such embodiments, the resulting wave drag is greater than zero, but reduced only slightly. In the illustrated embodiment, the reduction in local free-flow compared to the free-flow is large enough that, by means of fluid manipulation with a properly configured conduit device, the magnitude of the local free-flow of IMSA 817 is less than the speed of sound of the fluid on IMSA 817. In such embodiments, the resulting wave drag can be significantly reduced. In the reference scenario, the IMSA 817 or an equivalent IMSA travels faster than the speed of sound relative to the surrounding fluid during nominal operation because the local free-flow is faster than the speed of sound at the location of the IMSA 817. Therefore, the IMSA 817 or an equivalent IMSA will be associated with wave drag in the reference scenario. For example, the equivalent IMSA in the reference scenario could be configured to generate the same lift as the IMSA 817 and have the same planar area and / or geometry. It is this wave drag associated with the disturbance generation device, which can be reduced by the fluid manipulation device configured according to the invention.

[0333] It should be noted that the principles of the present invention can also be used to reduce wave drag associated with transonic flows. In other words, the free-flow velocity can be less than the speed of sound in the free flow, and the fluid manipulation device can be configured according to the present invention to reduce the local free-flow velocity of the IMSA, IMCA, or other disturbance generating device to a magnitude less than the free-flow velocity, such that the combined wave drag associated with the disturbance generating device and the fluid manipulation device can be lower than the wave drag associated with the equivalent disturbance generating device in the prior art. The latter wave drag can be, for example, the wave drag associated with the equivalent disturbance generating device in the reference case, where the local free-flow velocity is substantially equal to the free-flow velocity.

[0334] As mentioned, for Figure 22 The illustrated embodiment can be a case where the fuselage device 719 travels alone at the same free-flow velocity as the duct device 700. For Figure 23 The illustrated embodiment can be a scenario where the IMSA 817 travels alone at the same free-flow velocity as the duct assembly 800. Another scenario for the duct assembly 800 can be a scenario where a theoretically supersonic aircraft travels at the same free-flow velocity as the duct assembly 800, wherein the weight of the aircraft is equal to the lift of the IMSA 817, and the geometry of the aircraft (such as the length of the aircraft or the volume of the fuselage) shares common features with the geometry of the duct assembly 800, such as the length or volume of the internal compartments.

[0335] The conduit device 800 is configured to reduce local free-flow near a disturbance-generating device (such as IMSA 817) in a manner that reduces wave drag associated with the conduit device 800 compared to fluid manipulation devices in the prior art. This can be achieved by configuring the fluid manipulation device such that, as mentioned, negligible or minor disturbances are applied only to external flow outside the conduit device 800, and gradual compression and deceleration of internal flow entering the conduit device 800 are used to suppress pressure increases through the outer wall of the conduit device, and gradual expansion and acceleration of internal flow exiting the conduit device 800. It should be noted that the suppression of pressure increases associated with the deceleration of internal flow is used to prevent or mitigate the transmission or transfer of disturbances applied to the internal flow by the conduit device to the external flow. Disturbances applied to the internal flow during compression are configured to be at least partially eliminated during expansion or before leaving the channel.

[0336] It should be noted that, typically, embodiments of the present invention do not require the inclusion of a duct device. Other embodiments may include a fluid manipulation device configured to perform at least a portion of the aforementioned functions of the duct device 800. Embodiments of the present invention include a fluid manipulation device configured to reduce local free-flow at a designated disturbance generating device, wherein the generated local free-flow may be greater than or less than the speed of sound, and wherein the disturbance generating device may be an IMSA or IMCA, such as a wing, propeller, control surface, or fuselage. The fluid manipulation device is also configured to artificially suppress pressure increases near the disturbance generating device. This can reduce the wave drag of the disturbance generating device and can mitigate the wave drag associated with the fluid manipulation device.

[0337] For example, a fluid manipulation device can be configured to apply a body force per unit mass to a fluid near a designated disturbance generating device. The magnitude and direction of this body force per unit mass can be configured to slow down the fluid upstream of the disturbance generating device, suppress or limit the increase in pressure generated near the disturbance generating device, and accelerate the fluid downstream of the disturbance generating device. Recall that in the case where the fluid is a liquid such as water, conversely, the fluid manipulation device can accelerate the flow upstream of the disturbance generating device and slow down the flow downstream of the disturbance generating device. Near the disturbance generating device, the flow can be considered to be protected from high-pressure "external" flow, i.e., the external flow can be considered to be constrained or suppressed. It should be noted that in such embodiments, a channel through the fluid manipulation device is not required. Instead, a body force per unit mass generating field can be generated outside the fluid manipulation device, where the streamlines passing near the disturbance generating device are referred to as "internal flow," and the remaining flows are referred to as "external flow," although both types of flows can occur outside the fluid manipulation device.

[0338] Various physical forces exist in per-unit-mass generation apparatuses and methods, as are known in the art. For example, fluid upstream of the perturbation generation apparatus may be ionized in an upstream portion of a fluid manipulation device and subsequently subjected to an electric field configured to slow, confine, and accelerate the ionized fluid near the perturbation generation apparatus before being deionized or neutralized again in a downstream portion of the fluid manipulation device. Alternatively or simultaneously, a magnetic field may be used. In some embodiments, the fluid may also be electrically or magnetically polarized.

[0339] Body force can arise from the presence of a potential field gradient. One such instance is the force generated by a potential gradient. For example, the elements of a fluid can be configured to be charged. In the context of fluids, the term "element" refers to the components of the fluid, such as molecules. In the case of gases, molecules can be, for example, positively or negatively ionized. By applying an electric field, body force per unit mass can be applied to the charged elements of the fluid via a fluid manipulation device.

[0340] In other embodiments, using, obtaining, or generating a fluid with a moving charge may be impossible or inconvenient. In such cases, the elements of the fluid can be polarized by applying an electric field, or these elements may already possess intrinsic polarization, as in the case of polar molecules (such as water). When placed in an electric field gradient, these polarized elements will experience body forces. It should be noted that, among other parameters, the magnitude of these forces depends on the orientation of the polarization axis relative to the electric field. Thus, the electric field can be configured to generate body forces per unit mass on polar elements in the fluid and, if necessary, on polarized elements in the fluid. The electric field can be applied in a variety of ways known in the art.

[0341] Magnetism can also be used to generate body forces. Fluids can contain diamagnetic, paramagnetic, or ferromagnetic elements. When magnetized, the elements in the fluid may form magnetic dipoles, or these elements may already possess intrinsic magnetic dipoles, such as electrons. When these magnetic dipoles are placed in a magnetic field with a non-zero curl or gradient, they experience body forces. It should be noted that, among other parameters, the magnitude of the body force is a function of the orientation of the magnetic dipoles relative to the local magnetic field. Therefore, an external magnetic field can be configured to generate a body force per unit mass on the magnetized elements in the fluid, and to magnetize the magnetized elements in the fluid if necessary. In addition to other methods known in the art, the magnetic field can also be generated by other ferromagnetic materials that are at least instantaneously magnetized, or by an electric current flowing through electromagnetic lines.

[0342] exist Figure 23In this configuration, the duct device 800 releases only a small amount of vorticity compared to the vorticity released by the IMSA 817. This is achieved in part by ensuring that the IMSA 817 is sufficiently far from the inner surface 816 so that the induced velocity of the IMSA 817 and the associated wake at the inner surface 816 are sufficiently small. It should be noted that any vorticity released by the duct device 800 or any induced velocity within the supersonic external flow can potentially induce wave drag on the external flow. Therefore, it may be advantageous for the duct device 800 to be large enough that neither the bound vorticity of the IMSA 817 nor any vorticity released by the IMSA 817 imposes a theoretically induced velocity at the inner surface 816, i.e., an induced local free-flow velocity. Such theoretically induced velocities cause theoretical boundary vortices associated with the duct device 800, or vortex releases caused by the duct device 800, as the theoretical constraint prevents fluid from flowing across the inner surface 816. At the trailing edge of the duct device 800, i.e., at the second opening 810, these released vortices induce shock waves and wave drag. The magnitude of this wave drag can be reduced by minimizing the disturbance of the IMSA 817 and the interference of its wake on the duct assembly 800. This can be achieved by appropriately configuring parameters such as the dimensions of the duct assembly 800, which can be measured based on the diameter or cross-sectional area at station 837 or the length of the duct assembly 800 downstream of the IMSA 817. For example, the position and dimensions of the IMSA 817 within the duct assembly 800, where dimensions can be measured based on the wingspan chord or reference area, the magnitude of the lift generated by the IMSA 817, and the fluid characteristics at station 837, where these characteristics can refer to the local free-flow velocity or density. It should be noted that by altering the local free-flow of the IMSA 817 and its wake, the duct assembly 800 can and does exert a significant disturbance on the IMSA 817 and its wake.

[0343] In the second contraction section 808 and the second expansion section 809, the vortex vanes of the IMSA 817 (as shown by streamline 841) accelerate together with the internal flow (i.e., the overall flow within channel 803) in the positive X direction. In the illustrated embodiment, at the second opening 810, the vortices in the vortex vanes of the IMSA 817 move in the positive X direction at a speed greater than the speed of sound, as is the case with the internal flow at that location. Downstream of the second opening 810, the vortex vanes of the IMSA 817 do not move at a speed greater than the speed of sound relative to the overall flow. Therefore, the vortex vanes can traverse from the internal flow to the external flow without causing shock waves at the interface. It should be noted that this is true even when there is a slip velocity, velocity difference, or velocity gradient between the internal and external flows.

[0344] In some embodiments, the wave drag associated with the acceleration of the vortex plate of the IMSA 817 ranges from a velocity less than the speed of sound relative to the conduit assembly 800 in a region with a substantially constant cross-sectional area within the conduit assembly 800 to a velocity greater than the speed of sound relative to the conduit assembly 800 at station 840, and in some embodiments may be small or negligible compared to the wave drag associated with an equivalent IMSA in the prior art. This is because the acceleration of the free vortices of the vortex plate, as well as the acceleration of most of the internal flow, prevents the vortex from moving faster than the surrounding fluid. By means of a fluid manipulation device such as the conduit assembly 800, a given vortex (bound or free) of the IMSA 817 is prevented or hindered from generating a significant induced velocity or inducing disturbance in the fluid moving at supersonic speeds relative to the vortex source. The gradual acceleration of the fluid in the second contraction 808 and the second expansion 809 can be used to reduce the intensity of any shock waves associated with the vortex plate of the IMSA 817.

[0345] Figure 24 Is Figure 23 The position shown is when viewed in the positive X direction. Figure 23 A cross-sectional view of the embodiment shown.

[0346] Streamline 841 is shown. The stagnant streamlines of IMSA 817, namely the streamlines incident on the leading edge stagnant point of the left wingtip of IMSA 817 and the streamlines originating from the trailing edge stagnant point of the left wingtip of IMSA 817, are indicated by dashed line 842. The inner surface 823 of IMSA 817 is shown.

[0347] Figure 25 Is Figure 24 The position shown is when viewed in the positive X direction. Figure 23 A cross-sectional view of the embodiment shown.

[0348] The cross-section of the theoretically released vortex vane at this location, as shown by dashed line 843, is represented by the IMSA 817. The roll-up of the vortex vane is schematically represented.

[0349] Figure 26 Is Figure 24 The position shown is when viewed in the positive X direction. Figure 23 A cross-sectional view of the embodiment shown.

[0350] The cross-section of the theoretically released eddy current plate at station 839 in IMSA 817 is indicated by dashed line 844. The convolution of the eddy current plate is further developed.

[0351] Figure 27 Is Figure 24 The position shown is when viewed in the positive X direction. Figure 23 A cross-sectional view of the embodiment shown.

[0352] The cross-section of the theoretically released vortex plate at this location, as indicated by the dashed line 845, is shown in IMSA 817. The convolution of the vortex plate is further developed.

[0353] The dashed line 846 shows the projection of the outer surface 815 onto a plane parallel to the YZ plane downstream of the sectional view.

[0354] Figure 28 Is Figure 24 The position shown is when viewed in the negative X direction. Figure 23 A cross-sectional view of the embodiment shown.

[0355] Figure 29 This is a cross-sectional view of another embodiment of the present invention. Figure 30 Some features and operating principles of the embodiments shown are similar to those described in other accompanying drawings, and therefore will not be repeated. Figure 30 The same details are described in the context of the other, and vice versa.

[0356] The duct assembly 850 surrounds the IMSA 892, and in some embodiments, it may be a wing, an upstream IMSA 908, a fuselage assembly 869, a downstream IMSA 919, and an engine 925.

[0357] In the illustrated embodiment, engine 925 may be described as a turbofan engine. In some embodiments, the drive shaft of engine 925 may be coupled to a gearbox. In some magnetic embodiments, engine 925 may be described as a turboshaft engine.

[0358] In the illustrated embodiment, the cross-section of the conduit device 850 is circular when viewed along the X-axis and is axially symmetrical about an axis parallel to the X-axis. The conduit device 850 can be considered an IMCA (Integrated Motion Compatibility Association). The conduit device 850 includes an outer surface 867 and a channel 853 having an inner surface 868 located between a first opening 854 and a second opening 862, wherein the channel includes a first contraction 855, a first expansion 856, a region where the cross-sectional area 857 of the channel 853 gradually increases when viewed in the X direction, a second expansion 858, a second contraction 860, and a third expansion 861. It should be noted that the terms "contraction" and "expansion" refer to the size of the radius of the axially symmetrical channel.

[0359] The fuselage assembly 869 includes a leading edge point 870, a trailing edge point 871, an inner surface 873, an outer surface 872, and a fuselage compartment 874, schematically separated from the rest of the fuselage by dashed lines 875. The fuselage assembly 869 is rigidly connected to the ductwork assembly by a plurality of support rods. In the illustrated embodiment, a single stator blade, such as stator blade 913, can also be considered as a support rod, and vice versa. In some embodiments, the fuselage may be configured to, for example, carry cargo, passengers, or fuel.

[0360] The conduit assembly includes a first compartment 880 within an upstream neck or conduit element 951 and a second compartment 882 within a downstream neck or conduit element 952. These compartments can serve a variety of purposes. In some embodiments, they can be used to store landing gear, fuel, or cargo.

[0361] It should be noted that the channel radius or geometry can be changed in different ways as a function of position along the X-axis, or configured differently for other embodiments or other operating conditions. In other embodiments, the cross-sectional geometry of channel 853 or outer surface 867 can be square, rectangular, or elliptical when viewed along the X-direction. In some embodiments, the cross-sectional geometry of channel 853 can be changed from square to circular in the positive X-direction, for example.

[0362] In some embodiments, the cross-sectional area of ​​the circular channel 853 can vary over time. For example, the channel radius at station 890 can be changed for different operating conditions. The radius can be increased or decreased according to the free-flow velocity. In this way, the characteristics of the flow through the conduit 853 can be altered and controlled, thereby allowing the principles of the invention to be applied under different free-flow conditions. For example, the presence or location of the shock wave within the first expansion section 856 can be adjusted by controlling the cross-sectional area of ​​the channel 853 at station 890. Various methods can be used to change the cross-sectional area of ​​the channel as a function of time. For example, a ramp connected to the conduit assembly 850 can be hydraulically extended into the channel, thereby reducing the cross-sectional area of ​​the channel. In another example, a spike located within the channel 853 can be moved axially along the length of the channel, i.e., along the X direction, toward or away from the contraction of the channel, thereby decreasing or increasing the annular cross-sectional area of ​​the channel 853, respectively.

[0363] Similarly, the cross-sectional area of ​​channel 853 at station 885 can be changed to ensure the required flow profile within channel 853 as well as upstream and downstream of channel 853.

[0364] The conduit device 850 may be constructed from bulk material 851, which may include metal alloys such as aluminum, steel, or titanium. In some embodiments, bulk material 851 includes composite materials, such as carbon fiber or glass fiber.

[0365] In some embodiments, IMSA 892 may be a wing. Figure 29 The cross-sectional view shows the airfoil section 893 of the IMSA 892, which has a trailing edge 895, an inner surface 899, and an outer surface 896. The IMSA 892 is rigidly connected to the duct assembly via a support rod 900. The stagnant streamlines of the IMSA 892, namely the streamlines incident at the leading edge stagnant point of the right wingtip of the IMSA 892 and the streamlines originating at the trailing edge stagnant point of the right wingtip of the IMSA 892, are indicated by the dashed line 901. Figure 29 During the supersonic, nominal, constant speed, and level cruise configurations shown, IMSA 892 is configured to generate lift, as shown in lift vector 941, which has a substantial component parallel to the Y-axis.

[0366] The upstream IMSA 908 comprises a propeller or a fan disk with fan blades or propeller blades (such as blade 911), mounted on a central hub 909 having a leading edge point 870. Stator blades, such as stator blade 913, are located downstream of the propeller. In other embodiments, there are no dedicated stator blades, and the upstream IMSA 908 consists of only a single fan disk or propeller. In another example, the upstream IMSA may consist of two coaxial and counter-rotating propellers. In the illustrated embodiment, the propeller blades and stator blades are configured to rotate about their long axis. In other words, the blade pitch angle can be adjusted for the stator and rotor blades of the upstream IMSA 908. Figure 29 During the supersonic, nominal, level cruise configuration shown, the fan and stator blades of the upstream IMSA 908 are feathered, i.e., in a low-drag configuration. In some embodiments, in this configuration, the rotor of the upstream IMSA 908 is stationary, i.e., does not rotate relative to the duct assembly 850. In other embodiments, the rotor of the upstream IMSA 908 may rotate in this configuration.

[0367] The downstream IMSA 919 comprises a propeller or a fan disk with fan blades or propeller blades (such as blade 922) mounted on a central shaft. Stator blades, such as stator blade 924, are located downstream of the propeller. In other embodiments, there are no dedicated stator blades, and the downstream IMSA 919 consists of only a single fan disk or propeller. In another example, the downstream IMSA may consist of two coaxial and counter-rotating propellers. In the illustrated embodiment, the rotor of the downstream IMSA 919 rotates in the same direction as the rotor of the upstream IMSA 908. In other embodiments, the direction of rotation of the downstream IMSA 919 may be opposite to that of the upstream IMSA 908. This can be used to reduce the torque acting on the duct assembly 850 about the axis of rotation parallel to the upstream and downstream IMSA due to the resistance acting on both the upstream and downstream IMSA, as explained in the context of the upstream IMSA 908, where the propeller blades and stator blades of the downstream IMSA 919 are configured to rotate about their long axis. In other words, the pitch angle of the stator and rotor blades of the downstream IMSA 919 can be adjusted. Figure 29 During the supersonic, nominal, level cruise configuration shown, the fan and stator blades of the downstream IMSA 919 are feathered, i.e., in a low-drag configuration. In some embodiments, in this configuration, the rotor of the downstream IMSA 919 is stationary, i.e., does not rotate relative to the duct assembly 850. In other embodiments, the rotor of the downstream IMSA 919 may rotate in this configuration.

[0368] In some embodiments, engine 925 may be a jet engine having a compressor 928, a combustion chamber 940, and a turbine 932 within a nacelle 931. The first stage of turbine 932 consists of a rotor disk with rotor blades (such as rotor blade 934) and a stator with stator blades (such as stator blade 935). The second stage of turbine 932 consists of a rotor disk with rotor blades (such as rotor blade 936) and a stator with stator blades (such as stator blade 937). Engine 925 has a dual-valve-spool configuration, with the first-stage rotor disk of turbine 932 driving a first valve spool 926, which in turn drives the rotor disk of compressor 928. Compressor 928 may have three stages, each consisting of a rotor disk with rotor blades (such as rotor blade 929 of the third stage) and a stator with stator blades (such as stator blade 930 of the third stage). The rotor disc of the second stage of turbine 932 drives a second valve core, which in turn drives the rotors of both upstream IMSA 908 and downstream IMSA 919, for example, via drive shafts 927, 915, and 916. Cushion 933 is configured to reduce the drag of engine 925 by reducing or avoiding flow separation at the outlet of turbine 932. A trailing point 871 is indicated for cowl 933.

[0369] In the illustrated embodiment, the inlet ramp or door 938 may be configured to prevent most of the internal flow from entering the engine 925. The inlet door 938 may be configured to close the inlet to the engine 925. The outlet door 939 may be configured to provide an aerodynamic or hydrodynamic cowling to the nacelle 931. Figure 29 During the supersonic, nominal, level cruise configuration shown, inlet door 938 and outlet door 939 are shown in a fully closed configuration. During this operating condition, thrust is provided by the injection and combustion of fuel by a flame stabilizer (such as flame stabilizer 724) within channel 853. During this operating mode, engine 925 can be considered off, i.e., completely powered off or in a state of not providing significant power. In other embodiments, engine 925 may remain on during supersonic, nominal, level cruise. For example, engine 925 may drive a generator to provide power to auxiliary systems on aircraft 850. This power can be used to charge batteries or consumed by electrical equipment such as flight computers or air conditioning units. Inlet door 938 and outlet door 939 in Figure 30 and Figure 31 The diagram is shown in a fully open configuration. In this configuration, a portion of the fluid flowing through channel 853 can be absorbed by or flow through engine 925, which, for example, generates power through the combustion of fuel.

[0370] As mentioned, the power generated by engine 925 is transmitted via a drivetrain to upstream IMSA 908 and downstream IMSA 919. In some embodiments, the drivetrain may include, for example, a clutch, drive shaft, gears, or gearbox. In other embodiments, the power generated by engine 925 may be electrically transmitted to upstream IMSA 908 and downstream IMSA 919. Engine 925 may power a generator, and at least a portion of the generated power may be transmitted via an electrical conductor to an electric motor, wherein the electric motor may be configured to power upstream IMSA 908 and / or downstream IMSA 919. A portion of the power may also be used to power the auxiliary electrical system of duct assembly 850. In some embodiments, the rotor disc of downstream IMSA 919 may be connected to drive shaft 927, such as... Figure 29 As shown, the drive shaft 927 can also be configured to drive a generator, the power of which can be transmitted via conductors surrounding the fuselage compartment 874 to an electric motor 908 that drives the rotor disk of the upstream IMSA.

[0371] Power is mechanically transmitted from drive shaft 927 to the upstream IMSA 908 via universal joints, guiding the drivetrain to the fuselage compartment 874. In the duct assembly 850, the universal joint is a constant velocity joint or CV joint, such as CV joint 907 that connects drive shaft 915 to drive shaft 916.

[0372] In the illustrated embodiment, the stator blades of the downstream IMSA 919 are configured to inject fuel into an adjacent fluid flow and stabilize the flame during combustion of the fuel. Therefore, the stator of the IMSA 919 can be considered a flame stabilizer. Figure 29 During the supersonic, nominal, level cruise configuration shown, the flame stabilizer is configured to inject fuel into channel 853 and stabilize the flame during combustion of the fuel. In this embodiment, and during this operating mode, channel 853 can operate in the same manner as a ramjet engine. The thrust exerted by the fluid on the duct assembly 850 is schematically represented by a thrust vector (such as thrust vector 943). It should be noted that the thrust is a result of the fluid pressure acting on the duct assembly 850. In other words, the thrust comes from the integral of the pressure acting on the wetted surface of the duct assembly 850. As a result, the magnitude of the internal flow velocity at station 891 is greater than the magnitude of the free flow velocity, i.e., the magnitude of the internal flow velocity at station 884.

[0373] By adjusting the pitch angle of the downstream and / or upstream IMSA or the orientation of the stator blades relative to the fluid, any residual torque exerted on the remainder of the duct assembly 850 by the combination of the upstream and downstream IMSA can be eliminated. In some embodiments, the stator blades may also be used for roll, pitch, and yaw control of the duct assembly 850. In other embodiments, a dedicated IMSA, similar to IMSA 892, may be located in a region of channel 853 where the fluid flows at subsonic speeds relative to the duct assembly, wherein the dedicated IMSA is configured to maintain roll, pitch, and / or yaw control. In yet another embodiment, a control surface may be located in a region within channel 853 where the fluid moves at supersonic speeds relative to the duct assembly. In some such embodiments, the control surface may be located at the trailing edge of the duct assembly, i.e., at the second opening 862. Pitch and yaw control can be achieved via thrust vectoring, for example, where thrust is generated by the acceleration of the internal flow. In some embodiments, a tail surface, such as a vertical or horizontal tail fin, may be mounted on the outer surface 867 and configured to interact with external flow (i.e., flow outside the cylindrical flow tubes 865 or 866).

[0374] As previously defined, embodiments of the invention are at least partially surrounded by fluid. Figure 29 In this context, fluids are compressible. For example, a fluid can be a gas such as air.

[0375] In some embodiments, Figure 29The operating conditions shown can be nominal horizontal cruise operating conditions. In the simplified case shown, the free flow relative to the center of mass of the duct device 850 is constant in time and spatially uniform in magnitude and direction, with the direction parallel to the X-axis. Under the operating conditions shown, the magnitude of the free flow velocity relative to the duct device 850 is greater than the speed of sound in the fluid. Since wind speed is assumed to be negligible in this case, this is equivalent to the duct device 850 moving relative to the fluid at a speed faster than the speed of sound in a stationary fluid in an inertial frame of reference. Figure 29 As shown by arrow 944, the free flow velocity relative to the conduit device 850 is aligned with and parallel to the X-axis, i.e., from the left side of the page to the right side of the page.

[0376] Dashed lines 865 and 866 indicate stagnant streamlines that are incident on the leading edge of the conduit assembly 850 or begin at the trailing edge of the conduit assembly 850. Therefore, streamlines 865 and 866 are part of a flow surface or flow tube that separates the fluid flowing around the conduit assembly 850 from the fluid flowing in the channel 853 of the conduit assembly 850. In this embodiment, the flow tube is circular when viewed along the X direction.

[0377] The fluid upstream of the conduit assembly 850 (such as at station 884) moves faster relative to the conduit assembly 850 than... Figure 29 The speed of sound in the fluid is shown in the configuration. The first contraction 855 and the first expansion 856 of channel 853 are configured to compress the fluid flowing through channel 853 in the positive X direction. A first throat is defined as a portion of channel 853 having the minimum cross-sectional area of ​​channel 853 between the first contraction 855 and the first expansion 856 when viewed along the X direction. The average velocity of the fluid relative to the conduit assembly 850 at the first throat (i.e., station 885) is approximately equal to the speed of sound in the fluid at that location. In this embodiment, upstream, such as at station 884, the average relative velocity is greater than the speed of sound, while downstream, such as at stations 887, 888, or 889, the average relative velocity is less than the speed of sound in the fluid. In the illustrated embodiment, the flow through channel 853 is substantially adiabatic and isentropic when friction is neglected. In other embodiments, a shock wave may be present between the first throat and station 887. In other words, the relative velocity of the fluid immediately downstream of the first throat can be faster than the speed of sound in the fluid, wherein the relative velocity decreases to a speed slower than the speed of sound throughout the shock wave, thereby generating a relative velocity slower than the speed of sound at station 887, ideally where there is an infinitely weak impact at the first throat. In a preferred embodiment, such a shock wave is configured to be located upstream of the upstream IMSA 908.

[0378] Both the second contraction 860 and the third expansion 861 of channel 853 are configured to expand the fluid flowing through channel 853 in the positive X direction. A second throat is defined as a portion of channel 853, having the minimum cross-sectional area of ​​channel 853 between the second contraction 860 and the third expansion 861 when viewed along the X direction. The average velocity of the fluid relative to the conduit assembly 850 at the second throat (i.e., station 890) is approximately equal to the speed of sound in the fluid at that location. In this embodiment, upstream, such as at station 887, the average relative velocity is less than the speed of sound, while downstream, such as at station 891, the average relative velocity is greater than the speed of sound in the fluid.

[0379] exist Figure 29 During the supersonic, nominal, level cruise configuration shown, the duct assembly 850 is configured to reduce local free-flow of disturbance-generating devices such as the upstream IMSA 908, fuselage assembly 869, IMSA 892, downstream IMSA 919, fuel injectors and flame stabilizers 924, or engine 925. The duct assembly 850 is also configured to achieve this reduction in local free-flow without generating unnecessarily large wave drag. This can be achieved by configuring the duct assembly as described above. For example, the diameter variation of the circular outer surface 867 of the duct assembly 850 in the downstream direction can be configured to be small and gradual. Disturbances imposed on the internal flow by the duct assembly during internal flow deceleration can be isolated from the external flow by the outer wall of the duct assembly, and at least a portion of these disturbances can be eliminated before the internal flow exits through the second opening 862. Any eddy release, such as that generated by IMSA 892 or upstream IMSA 908, can be configured to occur within the conduit assembly 850 at a localized free-flow velocity reduced compared to the free-flow velocity, such that the wave drag associated with the release process is reduced or negligible compared to the reference case. As mentioned, the same principle can be applied to other disturbances, such as trapped eddies or IMCAs, engine or fuel combustion. The disturbance or localized free-flow velocity change imposed by trapped or free eddies within the conduit assembly 850 (such as the inner surface 868 of the conduit assembly 850) is low, so that the conduit assembly 850 does not generate unnecessarily large wave drag, where the associated waves can be in the internal or external flow. This can be achieved by ensuring that the diameter of the channel 853 is sufficiently large relative to the strength and location of the eddies. The strength of the trapped or free eddy filaments and their distance to the inner or outer surface of the conduit assembly are some parameters that determine the intensity of the disturbance. It should be noted that although not all disturbances carry or release eddies, such as those generated by fuel combustion, the principles of the present invention also apply to such disturbances.

[0380] During supersonic, nominal, level cruise, the majority of the weight of the duct assembly 850 is supported by the lift 941 generated by the IMSA 892, while the majority of the thrust is generated by the channel 853, which can be configured as a ramjet engine. For example, the duct assembly 850 can be described as a supersonic aircraft. Figure 29 In the middle, the conduit device 850 moves at supersonic speed in the negative X direction parallel to the X-axis relative to the stationary free-flowing fluid.

[0381] Figure 30 yes Figure 29 The figures shown are cross-sectional views of embodiments for different operating modes. Figure 30 In this configuration, the duct assembly 850 moves at a subsonic speed parallel to the X-axis in the negative X-direction relative to the stationary free-flowing fluid. The direction of the free-flowing fluid relative to the duct assembly 850 is indicated by arrow 950. In this configuration, the lift 945 acting on the duct assembly 850 carries a portion of the weight of the duct assembly 850. The longitudinal axis of symmetry of the duct assembly 850 rotates in the negative Z-direction. The angle of attack generated by the duct assembly 850 causes the internal and external flows to deflect in the negative Y-direction, thereby generating lift and drag acting on the duct assembly 850. During this operating mode, the duct assembly 850 can be considered as a closed wing or annular wing.

[0382] To minimize interference between IMSA 892 and downstream IMSA 919, IMSA 892 is feathered during this operating mode. Interference can cause flow field deformation at downstream IMSA 919, potentially leading to unwanted drag, noise, and vibration. Therefore, the shape of IMSA 892 is altered in a simplified, frictionless manner without releasing any eddies. In some embodiments, IMSA 892 can be deformed such that the outboard angle and angle of attack of each airfoil portion of IMSA 892 are zero. In other embodiments, IMSA 892 can be retracted into a fairing or mounted flush with an inner surface (such as inner surface 868 or fuselage outer surface 872). This reduces the wetting area of ​​the duct assembly 850 while minimizing or reducing any interference between IMSA 892 and downstream IMSA 919.

[0383] The upstream IMSA 908 is configured to generate thrust in the upstream direction, as shown by thrust vector 946, and the downstream IMSA 919 is configured to generate thrust in the downstream direction, as shown by thrust vector 949. This increases the mass flow rate through channel 853 and reduces the induced drag associated with generating lift and thrust. It should be noted that the upstream IMSA 908 and downstream IMSA 919 generate a net thrust in the upstream direction, which counteracts the drag acting on the conduit assembly 850 and contributes to the net lift of the conduit assembly 850.

[0384] The power consumed by the upstream IMSA 908 is provided by the internal flow of the downstream IMSA 919 and the power extracted by the engine 925.

[0385] exist Figure 30 During subsonic, nominal, level cruise, no fuel flow enters the internal flow via the flame stabilizer, nor is fuel burned within the internal flow, except within the combustion chamber 940 of engine 925. In other operating modes, similar to the operation of an afterburner, the flame stabilizer can inject and burn fuel in channel 853. Similarly, fuel can also be injected and burned directly downstream of turbine 932 in engine 925.

[0386] Dashed lines 959 and 960 indicate stagnant streamlines that are incident on the leading edge of the conduit assembly 850 or begin at the trailing edge of the conduit assembly 850. Therefore, streamlines 959 and 960 are part of a flow surface or flow tube that separates the external flow (i.e., the fluid flowing around the conduit assembly 850) from the internal flow (i.e., the fluid flowing in the channel 853). In this embodiment, the flow tube is circular when viewed along the X direction.

[0387] exist Figure 30 In the operating mode shown, the thrust of the downstream IMSA 919 can decrease as the free-flow velocity increases. Figure 30 and Figure 31During the operating mode shown, the purpose of the downstream IMSA 919 is to increase the mass flow rate through channel 853. As the free-flow velocity increases, the service of the downstream IMSA 919 is only required to a lesser extent. Therefore, the thrust of the downstream IMSA 919 can be reduced. Depending on the net thrust requirement, the thrust of the upstream IMSA 908 can decrease or increase with increasing free-flow velocity. At low free-flow velocities, the thrust generated by the upstream IMSA 908 may be limited by structural constraints or power limitations of engine 925. With increasing free-flow velocity, or at the aforementioned low free-flow velocities, the thrust generated by the upstream 908 may also be limited by increased wave drag, compressive drag, or noise of the rotor blades of the upstream IMSA 908. Wave drag can be generated by the tip velocity of the rotor or fan of the upstream IMSA 908 relative to the fluid exceeding the speed of sound at that location. Parts of the rotor blades of the upstream 908 may also encounter compressible drag at high velocities relative to the surrounding fluid. As the thrust of the upstream IMSA 908 decreases, the thrust of the downstream IMSA 919 also decreases to meet a given net thrust requirement. At sufficiently high free-flow velocities, the thrust of the downstream IMSA 919 is so small that feathering downstream of the IMSA 919 is more advantageous. Therefore, the downstream IMSA 919 can be disengaged from the drivetrain via a clutch and feathered, while the upstream IMSA 908 continues to provide thrust. In this configuration, the upstream IMSA 908 and engine 925 can be considered to operate as conventional turbofan engines, with the fan represented by the upstream IMSA 908 and the core represented by engine 925.

[0388] As the speed increases further, the thrust and rotational speed of the upstream IMSA 919 rotor can be reduced to avoid or reduce wave drag and / or compressibility drag associated with the rotor blades of the upstream IMSA 919. As previously stated, the upstream IMSA 908 and engine 925 can be considered conventional turbofan engines, although the percentage of thrust generated by the fan (i.e., the upstream IMSA 919) is reduced. The remaining portion of the required thrust can be provided by the acceleration of the fluid through engine 925, which itself can be considered as a turbojet engine.

[0389] When the free-flow velocity approaches and exceeds Mach 1, the afterburner of engine 925 can optionally engage to compensate for the reduced thrust and speed of the upstream IMSA 908 near the Mach 1 engine and to help engine 925 meet net thrust requirements. Alternatively or simultaneously, fuel can be injected and burned at channel 889 within channel 853 by a flame stabilizer and fuel injectors. As the velocity increases to above Mach 1, the local free-flow velocity of the upstream IMSA 908 decreases, allowing the rotational speed and the thrust generated by the upstream IMSA 908 to increase again. At sufficiently high velocities, any fuel entering the afterburner of engine 925 or flowing internally at station 889 can be reduced or completely stopped to improve fuel efficiency. At such velocities, the upstream IMSA 908 and engine 925 can be considered as a supercruise turbofan engine. During some operating modes, this reduction in fuel flow is not required to aid in the acceleration of duct assembly 850. As the speed increases further, any fuel flow entering the afterburner chamber of engine 925 or in the internal flow at station 889 can be increased. Fuel can be injected into channel 853 and burned through flame stabilizers and injectors (such as flame stabilizer 924). The portion of the internal flow in channel 853 that remains outside engine 925 can therefore be considered as operating as a ramjet engine in this mode of operation. As the speed increases further, the thrust generated by upstream IMSA 908 can decrease, and upstream IMSA 908 can also be feathered, which corresponds to Figure 29 The configuration shown.

[0390] The preceding description describes acceleration from subsonic to supersonic speeds. It should be noted that the wave drag associated with the conduit assembly 850 is relatively low during this acceleration. This is not to say that such acceleration can be achieved in other ways. For example, a shock wave could be allowed to form upstream of the first opening 854. This shock wave could be generated, for example, by a separate dedicated shock body (such as a separate fuselage). Alternatively, a shock wave could be generated by appropriately reducing the cross-sectional area of ​​channel 853 at station 890 or station 885. Compared to the above, this would reduce the mass flow rate through channel 853 and increase the thrust and rotational speed of the upstream IMSA 919 rotor near Mach 1 and at supersonic speeds. However, this could introduce wave drag and create noise pollution. The reduction in the mass flow rate through channel 853 could also increase the induced resistance or induced power of the conduit assembly 850.

[0391] Figure 31 yes Figure 29 The diagram shows a cross-sectional view of an embodiment for different operating modes. This operating mode can be described as constant-speed climb. It should be noted that the configuration of the duct device 850 during hovering flight is similar to... Figure 31The configuration shown is described. The duct device 850 can be described as a vertical takeoff and landing (VTOL) aircraft capable of supersonic flight.

[0392] exist Figure 31 In this configuration, the conduit assembly 850 moves at a subsonic speed in the positive Y direction parallel to the Y-axis relative to the stationary free-flowing fluid. The direction of the free-flowing fluid relative to the conduit assembly 850 is indicated by arrow 958.

[0393] Dashed lines 961 and 962 indicate stagnant streamlines that are incident on the leading edge of the conduit assembly 850 or begin at the trailing edge of the conduit assembly 850. Therefore, streamlines 961 and 962 are part of a flow surface or flow tube that separates the external flow (i.e., the fluid flowing around the conduit assembly 850) from the internal flow (i.e., the fluid flowing in the channel 853). In this embodiment, the flow tube is circular when viewed along the X direction.

[0394] The upstream IMSA 908 is configured to generate thrust in the upstream direction, as shown by thrust vector 955, and the downstream IMSA 919 is configured to generate thrust in the downstream direction, as shown by thrust vector 841. As mentioned, this increases the mass flow rate through channel 853 and reduces the induced drag associated with thrust generation. It should be noted that the upstream IMSA 908 and downstream IMSA 919 generate a net thrust in the upstream direction, which counteracts the traction drag and gravity acting on the duct assembly 850 during uniform ascent.

[0395] The power consumed by the upstream IMSA 908 is provided by the power flowing internally from the downstream IMSA 919 and the power extracted from the engine 925. In this embodiment, the power is mechanically transmitted to the upstream IMSA 908 via a drivetrain including a driveshaft (such as driveshaft 915).

[0396] exist Figure 31 During subsonic, nominal, constant-speed, and vertical climb, no fuel flows into the internal flow via the flame stabilizer, nor does fuel burn within the internal flow, except within the combustion chamber 940 of engine 925. In other operating modes, similar to the operation of an afterburner, the flame stabilizer can inject and burn fuel in channel 853. Similarly, fuel can also be injected and burned directly downstream of turbine 932 in engine 925.

[0397] for Figure 31 The operating modes shown are as follows: Figure 30 As described in the context, IMSA 892 is feathered. It should be noted that IMSA 892 can be used as a control surface, or the control surfaces of IMSA 892 can remain active during the feathering configuration of IMSA 892.

[0398] During landing, the duct assembly 850 can deploy its landing gear and, in a manner similar to... Figure 31 The configuration shown is perpendicular to the ground. Takeoff and hovering flight can follow the same principle. After takeoff, the duct device 850 can... Figure 31 The operating mode shown is switched to Figure 30 The operating mode shown, and then switched to Figure 29 The operating modes are shown. For example, switching can be accomplished using the same mechanism as pitch control. As mentioned, this can be done, for example, via control surfaces or thrust vectors.

[0399] In some embodiments, the conduit assembly 850 may include slots that allow fluid to pass through an outer surface 867 and an inner surface 868. These slots may be located downstream of the contraction 951, i.e., downstream of the first contraction 855 and downstream of the first expansion 856, and upstream of the upstream IMSA 908. In some embodiments, the slots may also pass through the contraction 951, i.e., through a portion of the first compartment 880. Slots may be located upstream of the contraction 952, i.e., upstream of the second contraction 860 and downstream of the downstream IMSA 919. In some embodiments, the slots may also pass through the contraction 952, i.e., through a portion of the second compartment 882. The slots may be arranged circumferentially around a cylindrical or circular conduit assembly 850. Doors or ramps may be configured to close or open the slots. For example, these slots may resemble the slots at the jet engine inlet of a Hawker Siddeley Harrier jet engine. During subsonic operation (such as subsonic cruise or climb), the trough can be in the open position, allowing fluid to flow into the upstream channel 853 of the upstream IMSA 908 and out of the downstream channel 853 of the downstream IMSA 919. This can increase the mass flow rate of the fluid through the upstream and downstream IMSAs. The trough can also be used to reduce flow separation at the first opening 854 and / or the second opening 862 or the first or second contraction 951 or the second contraction 952 by allowing flow to bypass the first contraction 951 or the second contraction 952. This reduces the intensity of the trapped eddies associated with the first or second contraction 951 or the second contraction 952 and can reduce the amount of flow separation. At higher free-flow velocities, such as supersonic, the trough can be closed, resulting in... Figure 29 The configuration shown is similar to the configuration shown.

[0400] In other embodiments, other types of disturbance generation devices within channel 853 may be used or employed, or different arrangements of disturbance generation devices such as IMCA, IMSA, or devices configured to increase or decrease fluid temperature may be used.

[0401] For example, in other embodiments, the fuselage of the duct assembly 850 may be replaced by the engine 925, which may be located upstream of, rather than downstream of, the downstream IMSA 919. Such embodiments do not require a wing, such as the IMSA 892 of the duct assembly 850, and the drivetrain may comprise a single straight shaft, in contrast to a series of shafts connected by universal joints or constant velocity joints. For example, such embodiments may be considered as and operate as turbofan jet engines.

[0402] In other variations of the duct assembly 850, the engine 925 may also be embedded within the fuselage assembly 869. In other words, the engine 925 may be located within or surrounded by the outer surface 872 of the fuselage assembly 869, and is located upstream of the downstream IMSA 919 and downstream of the upstream IMSA 908. Air may be supplied to the engine 925 via a duct that enters the fuselage assembly 869 from the channel 853. Other variations of the duct assembly 850 do not have a downstream IMSA similar to the downstream IMSA 919. In some embodiments, the rotor of the upstream IMSA 919 may be powered by at least one electric motor, which in turn may be powered by, for example, a battery.

[0403] In other embodiments, the aircraft may be configured to maintain a basic level during takeoff, hovering, or landing. In other words, as... Figure 29 As shown, during VTOL operation, the long axis can be substantially parallel to the X-axis. Therefore, embodiments configured in a manner similar to catheter device 850 can have the following variations compared to catheter device 850.

[0404] As previously described, the outer wall of the duct assembly may have a groove extending circumferentially around the duct assembly. The groove may be located between IMSA 908 and IMSA 919, i.e., near station 887. It should be noted that the groove needs to be large enough to allow sufficient fluid flow through the duct assembly to support its weight. In other embodiments, the groove may also be described as a door leading to the interior of the duct assembly or channel 853. In some embodiments, the groove is located only on the top of the duct assembly, i.e., the portion in the positive Y direction, to prevent or reduce vortex ring conditions and re-intake of engine exhaust by engine 925.

[0405] and Figure 30Compared to the nominal subsonic cruise shown, the rotation direction of IMSA 908 and 919 can be reversed. This can be achieved via a gearbox and clutch configured to change the rotation direction of the drive shafts driving the IMSA 908 and 919. If the IMSA 908 or 919 is driven by an electric motor, the rotation direction of the electric motor can be reversed. Furthermore, the individual blades of the IMSA 908 and IMSA 919 are configured to rotate approximately 180 degrees about their long axis (i.e., the radially outward axis). In other embodiments, during VTOL operation, it is not necessary to reverse the rotation direction of the rotors of the IMSA 908 and IMSA 919 compared to subsonic, nominal level cruise. For example, the airfoils of the rotors of the IMSA 908 and IMSA 919 can be symmetrical, or they can have a sufficiently small canard angle or twist so that the direction of the thrust vector can be reversed without changing the rotation direction of the airfoil of the rotors of the IMSA 908 and IMSA 919. It should be noted that each stator blade of the IMSA can be used to mitigate any efficiency losses associated with operating the rotor in a thrust-reverse manner compared to subsonic, nominal horizontal cruise.

[0406] Additionally, the portion of the duct preceding the second opening 862 can be bent, and in some cases can extend approximately 90 degrees. Similarly, the portion of the duct near the first opening 654 can be bent, and in some cases can extend approximately 90 degrees. The portions of the duct near the first opening 854 and the portions of the duct near the second opening 862 can rotate about the aircraft's roll axis and pitch axis. These rotating portions of the duct assembly can be configured, for example, in a manner similar to the rotating duct downstream of the main engine of the Lockheed F-35. In different embodiments, similar to the bucket used in conventional thrust reversers for jet engines, a curved or deflecting portion of the nominally straight duct wall can be provided to redirect or redirect the flow by extending a ramp or bucket into the flow. Alternatively or simultaneously, during nominal VTOL operation, guide vanes can be used to deflect the fluid in a downward direction, i.e., the negative Y direction. These vanes can be reconfigured to redirect the flow in the desired direction, for example, this direction can have two degrees of freedom, or "DOF," relative to the volume of the duct assembly. These DOFs can include the rotation of the flow exiting the ductwork around the pitch or roll axis of the aircraft.

[0407] During the nominal hover period, i.e., without disturbance, the flow enters the conduit assembly through the slot near station 887. This flow then branches and moves towards IMSA 908 or IMSA 919. Similar to... Figure 29In the scenario shown, the thrust generated by IMSA 908 is directed in the positive X-direction, i.e., upstream of the hovering position, and the thrust generated by IMSA 919 is directed in the negative X-direction, also upstream of the hovering position. After being accelerated by IMSA 919 or IMSA 908, the fluid deflects 90 degrees from a direction substantially parallel to the X-axis to a direction substantially parallel to the Y-axis, pointing in the negative Y-direction. Now, the planes of the second opening 862 and the first opening 854 are no longer parallel to the YZ plane, but are parallel to the XZ plane during the nominal hovering period.

[0408] In the foregoing embodiments, the power consumed during hovering is provided by engine 925. It should be noted that, as described above, such embodiments of the invention enable both vertical and horizontal VTOL operation.

[0409] During hovering, roll control can be provided via the stator blades of the IMSA 908 or IMSA 919. Roll control can also be provided via the thrust vector when the line of action of the net thrust vector does not pass through the center of mass. Pitch and yaw control can be provided by adjusting the plane of the first or second opening of the rotating duct assembly (i.e., via the thrust vector) and by adjusting the magnitude of the thrust of the IMSA 908 or IMSA 919. Position control can be provided by the net thrust and thrust vector of the IMSA 908 and IMSA 919. Recall that the individual rotor blades of the IMSA 908 and IMSA 919 can rotate about their long axis to allow for thrust control with sufficient amplitude over sufficient time.

[0410] In other embodiments capable of horizontal VTOL operation, the flow direction can be reversed compared to the above scenario. Instead of drawing in fluid through a central channel (i.e., the channel near station 887), fluid can be discharged through a series of central channels. The thrust direction of the IMSA908 is the negative X direction, and the thrust direction of the IMSA 919 is the positive X direction, which is consistent with... Figure 30 The thrust direction is the same during the nominal horizontal cruise at subsonic speeds. This simplifies the design of IMSA 908 and IMSA 919. The trough can contain thrust vectoring devices, which can be used to ensure the stability and control of the aircraft. For example, the trough can contain guide vanes configured to control the direction of fluid exiting the trough. The troughs can be positioned sufficiently far apart from each other along the walls of the duct assembly to facilitate sufficient pitch and yaw control authority. It should be noted that such embodiments draw in fluid through the first opening 854 and the second opening 862, which does not require the aforementioned nominal 90-degree bend. However, such a bend can improve the controllability of the aircraft. IMSA 908 and IMSA 919 are used to increase pressure or power the flow at station 887, where the flow enters the trough inlet and then exits through the trough outlet in a direction determined by guide vanes near the outlet, where the guide vanes are controlled, for example, by a flight control computer.

[0411] In some of these other embodiments, the inlet of engine 925 is located downstream of IMSA 908, but upstream of the inlet of the slot on inner surface 868. In this way, the engine does not reabsorb its own exhaust during horizontal VTOL operation.

[0412] In some of these other embodiments, the inlet of the slot is one of a plurality of openings on the inner surface 868 of a channel circumferentially located between IMSA 908 and IMSA 919, while the outlet of the same slot is located at one of four locations on the outer surface 867 of the conduit assembly. The outlet of the slot is connected to the corresponding inlet via a conduit, channel, or pipe passing through the wall of the conduit assembly. Two outlets may be located in the first compartment 880, and two outlets may be located in the second compartment 882. Figure 29 In the scenario shown, these outlets can be offset from each other in the Z direction and are typically oriented towards the negative Y direction. Guide vanes can be located directly upstream of the outlets, where they can be configured to control the flow direction of the fluid exiting through the outlets. Valves within the pipe can regulate the mass flow rate of the fluid through a given outlet. The inlet and outlet of the tank can be closed by gates to ensure smooth outer surfaces 867 and inner surfaces 868 during non-VTOL operation.

[0413] The benefits of horizontal VTOL operation include, among other things, more comfortable patient transport and reduced wind disturbance near the ground. Such wind disturbances are typically oriented parallel to the ground, and by aligning the aircraft in the dominant direction of these disturbances, drag caused by the disturbances can be reduced.

[0414] In some embodiments, the combustion chamber or flame stabilizer may be located upstream of the downstream IMSA 919 and downstream of the upstream IMSA 908. The combustion chamber may, for example, be located at station 887. In some operating modes, channel 853 can therefore be considered as a turbojet engine and operates as such. An additional flame stabilizer may be located downstream of the IMSA 919 and operate as an afterburner for the turbojet engine.

[0415] In some embodiments, a portion of the engine 925 may be located in the portion of the channel 853 corresponding to the third expansion 861. This can reduce the overall length of the conduit assembly 850, i.e., the extent of the conduit assembly 850 along the central axis, which can reduce the overall wetting area and viscous resistance. However, in some embodiments, this can increase wave drag.

[0416] Unless otherwise specified or explicitly stated in the context, the term “or” is equivalent to “and / or” in this document.

[0417] The embodiments and methods described herein are intended only to illustrate and demonstrate the principles of the invention. The invention can be practiced in several different ways and is not limited to the examples, embodiments, arrangements, configurations, or methods of operation described herein or depicted in the accompanying drawings. This also applies to situations where only one embodiment is described or depicted. Those skilled in the art will be able to devise many alternative examples, embodiments, arrangements, configurations, or methods of operation, although not shown or described herein, that embody the principles of the invention and are therefore within its spirit and scope.

[0418] aspect

[0419] Furthermore, the present invention is described in the following aspects.

[0420] Aspect 1. A system for reducing wave drag, the system comprising: an outer surface configured to receive an external fluid flow of a fluid; a channel coupled to the outer surface and configured to receive an internal fluid flow of the fluid, the channel including a fluid inlet and a fluid outlet, the channel being configured to manipulate the internal fluid flow to reduce wave drag; wherein the channel includes: a first fluid manipulation device (“FMA”) configured to receive the internal fluid flow downstream of the fluid inlet and further configured to change the velocity and pressure of the fluid flow within the channel; a pressure containment device (“PCA”) configured to receive the internal fluid flow downstream of the first FMA; and a second FMA configured to receive the internal fluid flow downstream of the PCA and upstream of the fluid outlet, the second FMA being configured to further change the velocity and pressure of the internal fluid flow, wherein the free flow has a free flow velocity greater than the wave velocity of a wave within the free flow.

[0421] Aspect 2. The system according to aspect 1, wherein the first FMA and / or the second FMA comprises a contractile catheter.

[0422] Aspect 3. The system according to aspect 1, wherein the first FMA and / or the second FMA comprises a dilator catheter.

[0423] Aspect 4. The system according to aspect 1, wherein the first FMA and / or the second FMA comprises a dilating catheter.

[0424] Aspect 5. The system according to aspect 1, wherein the first FMA and / or the second FMA comprises a propeller or thrust generating device.

[0425] Aspect 6. The system according to aspect 1, wherein the first FMA and / or the second FMA comprises a physical strength generation device.

[0426] Aspect 7. The system according to aspect 1, wherein the fluid is compressible.

[0427] Aspect 8. The system according to aspect 7, wherein the fluid is a gas containing air, nitrogen or carbon dioxide.

[0428] Aspect 9. The system according to aspect 7, wherein the first FMA is configured to slow down the internal fluid flow and increase the pressure relative to the free flow.

[0429] Aspect 10. The system according to aspect 9, wherein the first FMA is configured to decelerate the internal fluid flow to a subsonic fluid velocity.

[0430] Aspect 11. The system according to aspect 9, wherein the first FMA is configured to decelerate the internal fluid flow to transonic speeds.

[0431] Aspect 12. The system according to aspect 9, wherein the first FMA is configured to slow the internal fluid flow to a lower supersonic speed.

[0432] Aspect 13. The system according to aspect 7, wherein the second FMA is configured to accelerate the internal fluid flow and reduce the pressure relative to the free flow.

[0433] Aspect 14. The system according to aspect 13, wherein the second FMA is configured to accelerate the internal fluid flow to a speed substantially equal to the free flow velocity.

[0434] Aspect 15. The system according to aspect 13, wherein the second FMA is configured to accelerate the internal fluid flow to a speed greater than the free flow velocity.

[0435] Aspect 16. The system according to aspect 13, wherein the second FMA is configured to accelerate the internal fluid flow to a velocity less than the free flow velocity.

[0436] Aspect 17. The system according to aspect 1, wherein the fluid is substantially incompressible.

[0437] Aspect 18. The system according to aspect 17, wherein the fluid comprises water.

[0438] Aspect 19. The system according to aspect 17, wherein the first FMA is configured to accelerate the internal fluid flow and reduce the pressure of the internal fluid flow relative to the free flow, thereby reducing the cross-sectional area of ​​the internal fluid flow leaving the first FMA and entering the PCA compared to an equivalent free flow cross-sectional area.

[0439] Aspect 20. The system according to aspect 19, wherein the first FMA is configured to accelerate the internal fluid flow, thereby reducing the total drag, including wave drag, on an aircraft containing the system.

[0440] Aspect 21. The system according to aspect 17, wherein the second FMA is configured to decelerate the internal fluid flow and increase the pressure of the internal fluid flow relative to the free flow, thereby increasing the cross-sectional area of ​​the internal fluid flow exiting the second FMA.

[0441] Aspect 22. The system according to aspect 21, wherein the second FMA is configured to reduce the internal fluid flow to a speed substantially equal to the free flow velocity.

[0442] Aspect 23. The system according to aspect 21, wherein the second FMA is configured to reduce the internal fluid flow to a speed greater than the free flow velocity.

[0443] Aspect 24. The system according to aspect 21, wherein the second FMA is configured to reduce the internal fluid flow to a speed less than the free flow velocity.

[0444] Aspect 25. The system according to aspect 1, wherein the PCA is configured to maintain a pressure difference between the internal fluid flow within the PCA and the free flow outside the outer surface.

[0445] Aspect 26. The system according to aspect 25, wherein the PCA includes a channel having a circular, rectangular, elliptical, or polygonal cross-section, and / or a straight edge segment, bend, elbow, or turn.

[0446] Aspect 27. The system according to aspect 1, wherein the PCA includes a wing configured to generate lift and transfer net momentum to the fluid within the PCA.

[0447] Aspect 28. The system according to aspect 1, wherein the PCA includes a fuselage.

[0448] Aspect 29. The system according to aspect 1, wherein the PCA includes an intentional momentum carrying device, an intentional momentum releasing device, a turboshaft engine, a turbofan engine, a turboprop engine, a turbojet engine, a ramjet engine, a thrust device, a drag device, a pump-jet engine, a propeller, or an afterburner.

[0449] Aspect 30. The system according to Aspect 1, wherein the PCA comprises: a first thrust device configured to apply a first induced velocity to a local free flow during a nominal operating requirement, the first thrust device generating a flow tube; and a second thrust device located downstream of the flow tube, the second thrust device configured to apply a second induced velocity to the local free flow, wherein the second induced velocity at the location of the second thrust device has a component in the opposite direction to the direction of the first induced velocity at the location of the second thrust device.

[0450] Aspect 31. The system according to aspect 30, wherein the first thrust device or the second thrust device comprises a propeller.

[0451] Aspect 32. The system according to aspect 30, wherein at least a portion of the power extracted by one thrust device is directed as power for another thrust device.

[0452] Aspect 33. The system according to aspect 1, wherein the volume between the outer surface and the inner surface comprises at least a portion of the aircraft, wherein the outer surface and the inner surface are configured to reduce the effect of wave drag in free flow.

[0453] Aspect 34. The system according to aspect 33, wherein the outer surface is substantially parallel to the free flow lines.

[0454] Aspect 35. The system according to aspect 33, wherein the outer surface comprises an annular cylinder, wherein the first FMA is located at an upstream end of the cylinder, and the second FMA is located at a downstream end of the cylinder.

[0455] Aspect 36. The system according to aspect 35, wherein the outer surface of the aircraft is in the shape of a conical cylinder, wherein the radius of the cylinder decreases in the downstream direction.

[0456] Aspect 37. The system according to aspect 33, wherein the cross-sectional area of ​​the outer surface is circular, elliptical, rectangular or polygonal when viewed along the free flow direction.

[0457] Aspect 38. The system according to aspect 33, wherein the aircraft is configured for vertical takeoff and nominal operation without inducing significant wave drag.

[0458] Aspect 39. The system according to aspect 33, wherein the aircraft is configured to fly at subsonic and / or supersonic speeds in horizontal cruise without inducing significant wave drag.

[0459] Aspect 40. The system according to aspect 1, wherein the outer surface and the inner surface form an intentional momentum-carrying device; wherein the system further includes a boundary device; and wherein the IMCA reduces the local free-flow velocity of the boundary device relative to the free-flow velocity.

[0460] Aspect 41. The apparatus according to aspect 40, wherein the reduction in the local free-flow velocity of the boundary device is higher than the reduction in the wave velocity within the local free-flow fluid.

[0461] Aspect 42. The apparatus according to aspect 40, wherein the local free-flow velocity of the boundary device is reduced to substantially equal to the velocity of the wave velocity within the local free-flow.

[0462] Aspect 43. The apparatus according to aspect 40, wherein the local free-flow velocity of the boundary device is reduced to less than the wave velocity within the local free-flow.

[0463] Aspect 44. The apparatus according to aspect 40, wherein the local free-flow velocity of the boundary device is reduced to a supersonic velocity within the local free-flow of the boundary device.

[0464] Aspect 45. The apparatus according to aspect 40, wherein the local free-flow velocity of the boundary device is reduced to a transonic velocity within the local free-flow of the boundary device.

[0465] Aspect 46. The apparatus according to aspect 40, wherein the local free-flow velocity of the boundary device is reduced to a subsonic velocity within the local free-flow of the boundary device.

[0466] Aspect 47. The apparatus according to aspect 40, wherein the boundary device comprises a fuselage or hull.

[0467] Aspect 48. The apparatus according to aspect 40, wherein the boundary device comprises a wing.

[0468] Aspect 49. The system according to aspect 40, wherein the boundary device includes a third FMA configured to deliver a net induced velocity to the far wake of a third FIA, wherein at least a portion of the far wake of the third FMA is located within the channel and is at a local free-flow velocity less than the free-flow velocity due to the reduction in local free-flow velocity upstream, downstream of the channel and near the third FIA.

[0469] Aspect 50. The apparatus according to aspect 49, wherein the induced velocity in the far wake transmitted from the third FIA to the third FMA has a non-zero net component perpendicular to the local free-flow flow within the PCA downstream of the third FMA.

[0470] Aspect 51. The apparatus according to aspect 50, wherein the third FIA is a wing and configured to generate lift during nominal level cruise operation, and wherein at least a portion of the far wake of the wing is located within a region of reduced local free flow within the channel, and wherein the far wake of the wing extends outside the outlet of the channel and into the free flow downstream therefrom.

[0471] Aspect 52. The system according to aspect 51, wherein the wingspan is less than half the effective diameter of the channel at the location of the wing.

[0472] Aspect 53. The system according to aspect 51, wherein the wingspan is less than one-quarter of the effective diameter of the channel at the location of the wing.

[0473] Aspect 54. The system according to aspect 51, wherein the wingspan is less than one-tenth of the effective diameter of the channel at the location of the wing.

[0474] Aspect 55. The apparatus according to aspect 49, wherein the induced velocity in the far wake transmitted from the third FIA to the third FMA has a non-zero net component parallel to the local free-flow.

[0475] Aspect 56. The apparatus according to aspect 55, wherein the third FIA is a fuselage or propeller and is configured to generate thrust or drag during nominal level cruise operation.

[0476] Aspect 57. The apparatus according to aspect 40, wherein the boundary device is located within the flow tube formed by the leading and trailing edges of the IMCA.

[0477] Aspect 58. A method for reducing wave drag of an aircraft, the method comprising: providing a first fluid manipulation device (“FMA”); providing a second FMA at least partially within a downstream flow channel of the first FMA; and providing a pressure containment device (“PCA”) configured to at least partially surround the flow channel passing through both the first FMA and the second FMA.

[0478] Aspect 59. The method according to aspect 58, wherein the fluid is compressible, and wherein the first FMA is configured to decelerate the fluid and increase the pressure of the fluid, and wherein the second FMA is configured to accelerate the fluid and decrease the pressure of the fluid, and wherein the method further includes providing a wing within the PCA such that lift is generated at a lower speed and higher pressure flow compared to free flow.

[0479] Aspect 60. The method according to aspect 58, wherein the fluid is incompressible, and wherein the first FMA is configured to accelerate the fluid and reduce the pressure of the fluid, and wherein the second FMA is configured to decelerate the fluid and increase the pressure of the fluid, and wherein the method further comprises transmitting a flow with lower pressure and lower cross-sectional area via the PCA through the aircraft from the first FMA to the second FMA, such that the aircraft generates less wave drag.

Claims

1. A system for reducing wave drag, the system comprising: An outer surface configured for external fluid flow during nominal operating conditions, the outer surface including a leading edge and a trailing edge; A channel configured for internal fluid flow during the nominal operating conditions, the channel including a fluid inlet and a fluid outlet, the fluid inlet being coupled to a leading edge of the outer surface and the fluid outlet being coupled to a trailing edge of the outer surface; A first fluid manipulation device ("FMA") is configured to manipulate the internal fluid flow within the flow tube during the nominal operating conditions, and is configured to reduce the velocity of the internal fluid flow in the downstream direction and increase the pressure of the internal fluid flow in the downstream direction. A second fluid manipulation device is configured to manipulate the internal fluid flow downstream of the first fluid manipulation device during the nominal operating conditions, and is configured to increase the velocity of the internal fluid flow in the downstream direction and decrease the pressure of the internal fluid flow in the downstream direction. A pressure containment device ("PCA") is configured to act on the internal fluid flow downstream of the fluid inlet and upstream of the fluid outlet, and is configured to maintain a pressure difference between the internal fluid flow and the external fluid flow. as well as A third fluid manipulation device is configured to manipulate the internal fluid flow downstream of the fluid inlet and upstream of the fluid outlet, and is configured to transmit a net induced velocity to the far wake of the third fluid manipulation device during the nominal operating conditions, wherein, at the location of the third fluid manipulation device, the local free-flow velocity of the third fluid manipulation device is less than the free-flow velocity, wherein at least a portion of the far wake of the third fluid manipulation device is located within the channel, within which the local free-flow velocity of the far wake of the third fluid manipulation device is less than the free-flow velocity, wherein the far wake of the third fluid manipulation device extends outside and downstream of the outlet of the channel, and wherein the induced velocity transmitted by the third fluid manipulation device to the far wake of the third fluid manipulation device has a non-zero net component perpendicular to the local free-flow of the far wake of the third fluid manipulation device within the pressure containment device downstream of the third fluid manipulation device. During the nominal operating conditions, the flow velocity of the free flow is greater than the wave velocity within the free flow, and the fluid is compressible. The system is configured to manipulate the internal fluid flow to reduce the wave drag of the third fluid manipulation device. The first fluid manipulation device includes a constriction catheter or a dilatation catheter during the nominal operating conditions. The pressure-retaining device includes a conduit during the nominal operating conditions. The second fluid manipulation device includes a constricting catheter, a dilating catheter, or a gradually dilating catheter during the nominal operating conditions.

2. The system of claim 1, wherein the fluid is a gas.

3. The system of claim 1, wherein the first fluid manipulation device is configured to reduce the internal fluid flow to a subsonic fluid flow velocity.

4. The system of claim 1, wherein the first fluid manipulation device is configured to decelerate the internal fluid flow to a transonic fluid flow speed.

5. The system of claim 1, wherein the first fluid manipulation device is configured to slow the internal fluid flow to a lower supersonic fluid flow velocity.

6. The system of claim 1, wherein the second fluid manipulation device is configured to accelerate the internal fluid flow to a speed equal to the free flow velocity.

7. The system of claim 1, wherein the second fluid manipulation device is configured to accelerate the internal fluid flow to a speed greater than the free flow velocity.

8. The system of claim 1, wherein the second fluid manipulation device is configured to accelerate the internal fluid flow to a speed less than the free flow velocity.

9. The system of claim 1, wherein the pressure-retaining device is configured to maintain a pressure difference between the internal fluid flow within the flow tube and the external fluid flow outside the flow tube.

10. The system of claim 1, wherein the first fluid manipulation device, the pressure containment device, or the second fluid manipulation device comprises a channel, wherein the flow tube passes through at least a portion of the channel, wherein the channel has a circular, rectangular, elliptical, or polygonal cross-section, and / or the channel has a straight side segment, a bend, an elbow, or a turn.

11. The system of claim 1, wherein the third fluid manipulation device comprises a wing configured to generate lift and transfer net momentum to the fluid within the pressure reservoir.

12. The system of claim 1, wherein the first fluid manipulation device, the pressure containment device, the second fluid manipulation device and / or the third fluid manipulation device comprises a fuselage.

13. The system of claim 1, wherein the internal fluid flow is manipulated downstream of at least a portion of the first fluid manipulation device and upstream of at least a portion of the second fluid manipulation device via an intentional momentum carrying device, fuselage, intentional momentum releasing device, turboshaft engine, turbofan engine, turboprop engine, turbojet engine, ramjet engine, thrust device, drag device, propeller, compressor, combustion chamber, turbine, or afterburner.

14. The system of claim 1, wherein the first fluid manipulation device, the pressure containment device, and / or the second fluid manipulation device comprises an intentional momentum carrier ("IMCA"). The intentional momentum-carrying device reduces the local free-flow velocity of the third fluid manipulation device at the third fluid manipulation device relative to the free-flow velocity, and The intentional momentum bearing device described herein includes an outer surface and an inner surface.

15. The system of claim 14, wherein during the nominal operating conditions, the local free-flow velocity of the third fluid manipulation device at the third fluid manipulation device is reduced relative to the free-flow velocity.

16. The system of claim 14, wherein the intentional momentum bearing device comprises a fuselage.

17. The system of claim 14, wherein the third fluid manipulation device comprises a wing.

18. The system of claim 1, wherein the third fluid manipulation device is configured to transmit a net induced velocity to the far wake of the third fluid manipulation device during the nominal operating conditions, wherein at least a portion of the far wake of the third fluid manipulation device is located within the internal fluid flow downstream of at least a portion of the first fluid manipulation device and upstream of at least a portion of the second fluid manipulation device, and wherein the induced velocity transmitted by the third fluid manipulation device to the far wake of the third fluid manipulation device has a non-zero net component perpendicular to the local free flow within the pressure containment device downstream of the third fluid manipulation device.

19. The system of claim 18, wherein the induced velocity transmitted from the third fluid manipulation device to the far wake of the third fluid manipulation device has a non-zero net component parallel to the local free flow in the far wake of the third fluid manipulation device.

20. The system of claim 18, wherein the third fluid manipulation device comprises a wing configured to generate lift during a nominal operating state and transfer net momentum to the fluid, and wherein at least a portion of the far wake of the wing is located within the internal fluid flow downstream of at least a portion of the first fluid manipulation device and upstream of at least a portion of the second fluid manipulation device, and wherein the far wake of the wing extends into the free flow downstream of the second fluid manipulation device.

21. The system of claim 20, wherein the flow tube passes through at least a portion of the channel, wherein the wingspan is less than half the effective diameter of the channel at the location of the wing.

22. The system of claim 20, wherein the flow tube passes through at least a portion of the channel, wherein the wingspan is less than one-third and / or one-quarter of the effective diameter of the channel at the location of the wing.

23. The system of claim 20, wherein the flow tube passes through at least a portion of the channel, wherein the wingspan is less than one-tenth of the effective diameter of the channel at the location of the wing.

24. The system of claim 1, wherein the third fluid manipulation device comprises a propeller, rotor, control surface, intentional momentum carrying device ("IMCA"), or intentional momentum releasing device ("IMSA").

25. The system of claim 14, wherein the third fluid manipulation device is located within the flow tube surrounded by the leading and trailing edges of the intentional momentum carrier.

26. The system of claim 1, wherein the first fluid manipulation device, the second fluid manipulation device and / or the pressure containment device are configured to reduce the local free-flow velocity of the third fluid manipulation device relative to the free-flow velocity.

27. The system of claim 26, wherein the flow velocity of the third fluid manipulation device in the local free flow of the third fluid manipulation device is reduced to a flow velocity less than the wave velocity of the third fluid manipulation device in the local free flow of the third fluid manipulation device.

28. The system of claim 26, wherein the local free-flow velocity of the third fluid manipulation device is reduced to a flow velocity greater than the wave velocity within the local free-flow of the third fluid manipulation device.

29. The system of claim 1, wherein the nominal operating conditions include stable nominal level cruise.

30. The system of claim 1, wherein during the nominal operating conditions, there is a thrust exerted on the system in the upstream direction by the internal fluid flow.

31. The system of claim 20, wherein thrust is generated via an intentional momentum release device, a turboshaft engine, a turbofan engine, a turboprop engine, a turbojet engine, a ramjet engine, a thrust device, a propeller, an afterburner, a compressor, fuel combustion in the combustion chamber, or an electric motor driving the intentional momentum release device.

32. The system of claim 1, wherein the first fluid manipulation device, the pressure containment device, and / or the second fluid manipulation device comprises an outer surface having a leading edge and a trailing edge, wherein the cross-sectional area of ​​the outer surface decreases in a downstream direction between the leading edge and the trailing edge.

33. The system of claim 1, wherein the system comprises a conduit device, wherein the conduit device includes the first fluid manipulation device and / or the second fluid manipulation device and / or the pressure-retaining device.

34. The system of claim 1, wherein the system includes a channel, and wherein the flow tube passes through at least a portion of the channel.

35. The system of claim 34, wherein the first fluid manipulation device, the pressure containment device, or the second fluid manipulation device is configured to change the cross-sectional area of ​​the channel.

36. The system of claim 35, wherein the first fluid manipulation device, the pressure containment device, or the second fluid manipulation device comprises a ramp or a translation spike.

37. The system of claim 14, wherein the volume between the outer surface and the inner surface comprises at least a portion of the aircraft, wherein the outer surface and the inner surface are configured to reduce the effect of wave drag on the aircraft in free-flow.

38. The system of claim 14, wherein the outer surface is parallel to the local free-flow velocity of the intended momentum-bearing device during the nominal operating conditions.

39. The system of claim 14, wherein the intentional momentum bearing device comprises an annular cylinder, wherein the first fluid manipulation device is located at the upstream end of the annular cylinder, and the second fluid manipulation device is located at the downstream end of the annular cylinder.

40. The system of claim 14, wherein the outer surface is in the shape of a conical cylinder, wherein the radius of the conical cylinder decreases in the downstream direction.

41. The system of claim 14, wherein the cross-sectional geometry of the outer surface is circular, elliptical, rectangular, or polygonal when viewed along a direction aligned with the free flow.

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