Airflow modification device

Abstract

A jet aircraft having an airflow modification device in its engine duct, the airflow modification device comprising an inlet, an outlet, and a flow path extending from the inlet to the outlet, wherein the device is positioned to receive an incoming airflow and is configured to at least partially modify the airflow within the flow path to improve the ordering of the incoming airflow, the airflow modification device further comprising at least one pitot sensor located at the inlet and integrated with the device, and a pressure line having a first end and a second end, the first end being connected to the pitot sensor and the second end being connected to a transducer, wherein the pressure line is completely enclosed within the device.

Description

Technical Field

[0001] The present invention relates to an airflow modification device for measuring pitot pressure for use in an engine duct, more specifically a jet engine duct.

Background Art

[0002] A pitot sensor is used to measure the flow velocity of a fluid and finds utility in measuring the airspeed of an aircraft. A pitot sensor generally comprises a tube with one end closed, and the open end is directed directly into the flow of an incident fluid such as an airflow. In use, the fluid flow moves into the tube and, due to there being no outlet in the tube, it stagnates there. The stagnation point pressure can be measured within this tube, and the fluid flow velocity can be calculated as a standard function of the difference between the stagnation point pressure and the ambient pressure.

[0003] Traditionally, pitot sensors are mounted on the exterior of vehicles, such as aircraft. They are typically mounted outside the boundary layer, away from the vehicle's surface, to neutralize fluid turbulence caused by the vehicle itself. Therefore, pitot sensors are particularly vulnerable to damage on the ground, and in the air, in the case of aircraft. This can be caused by accidental contact between a person or instrument and an exposed pitot sensor, damaging the sensor, or during flight, for example, by a bird strike or contact with an aerial refueling drogue. Furthermore, pitot sensors can be blocked by nesting insects or windblown debris unless properly covered. Damaged or blocked pitot sensors are particularly dangerous to aircraft safety because they can cause the airspeed indicator in the cockpit to give inaccurate readings, potentially leading to fatal errors in pilot control of the aircraft or causing subsystems that use such data, such as the autopilot, to malfunction. Furthermore, in the case of military stealth aircraft, exposed protrusions extending from the aircraft's surface are undesirable because they increase radar reflectivity, thereby increasing the aircraft's overall radar cross-section. Therefore, the possibility of damage to the pitot sensor must be reduced or eliminated, at least partially.

[0004] US2017284304 discloses a system and method for regulating airflow distortion in a gas turbine engine using a valved airflow assembly. The valve can control the airflow and regulate airflow distortion. [Overview of the project]

[0005] According to one aspect of the present invention, an airflow modification device for use in an engine duct is provided, the airflow modification device comprising an inlet, an outlet, and a flow path extending from the inlet to the outlet, wherein the device is positioned to receive an incoming airflow and is configured to at least partially modify the airflow in the flow path to improve the flow ordering of the incoming airflow, the airflow modification device further comprising at least one pitot sensor located at the inlet and integrated with the device, and a pressure line having a first end and a second end, the first end being connected to the pitot sensor and the second end being connected to a transducer, wherein the pressure line is completely enclosed within the device.

[0006] The air pressure of the incoming airflow can be measured directly at the engine surface via an integrated pitot sensor within an airflow diversion device, without requiring an externally mounted pitot sensor that may be damaged or contribute to an increased radar cross-section when used on military stealth aircraft. Airflow diversion devices may be used in engine ducts. An engine duct is a plenum designed to guide air from the outside atmosphere to the engine surface of the engine. In modern military aircraft, engines are typically located within the aircraft fuselage for several reasons, including reducing the aircraft's rolling moment, allowing the incoming airflow to be sufficiently decelerated, and reducing the aircraft's radar cross-section. The incoming airflow to the aircraft is guided from the outside atmosphere to the engine surface by the engine duct. The engine duct may follow a linear path or a convoluted path, meaning that one or more diversions may be provided within the engine duct to guide the incoming air to the engine surface. In both linear and convoluted engine ducts, the incoming airflow is disturbed from laminar to turbulent, resulting in circumferential pressure asymmetry, or radial non-uniformity, in a given cross-section of the engine duct. Circumferentially asymmetric incoming airflow is undesirable on the engine surface, as it degrades engine performance and can even lead to stalling of some blades on the engine fan. Therefore, one or more airflow modification devices may be used in the engine duct to at least partially restore the incoming airflow to laminar, so that the incoming airflow is more circumferentially symmetrical on the engine surface.

[0007] The inventors have found that by incorporating a Pitot sensor within an airflow modification device, it is possible to estimate the accurate measurement of the incoming airflow to an aircraft, eliminating the need for an external Pitot sensor to be mounted on the aircraft. Therefore, the airflow modification device includes a Pitot sensor located at the inlet of the airflow modification device. The Pitot sensor is integrated with the airflow modification device, so that it does not protrude from the outer surface of the device. The Pitot sensor is generally oriented substantially in the direction of the incoming airflow. A pressure line is connected to the Pitot sensor at a first end. The pressure line may be connected to a transducer at a second end. The pressure line may be a hollow passage formed within the device, so that the incoming air can collect and stagnate within the passage, where the transducer is configured to measure the stagnation pressure in the pressure line in order to estimate the airspeed. Alternatively, the pressure line may be formed from a separate material within the device, for example, as a hollow tube embedded within the device. The pressure line is completely enclosed within the airflow modification device. In other words, the pressure line does not extend outside the outer mold line of the airflow changing device between the first and second ends, thereby minimizing further flow turbulence in the engine duct before the air reaches the engine surface.

[0008] In some configurations, the airflow modification device may have a spoke design. The spoke design may comprise a core hub and at least one blade extending radially therefrom. Each blade may comprise a blade root located proximal to the core hub and a blade tip located distal to the core hub. The blade(s) may be enclosed by a housing. The blades may have an integrated pressure line positioned to connect a pitot sensor to the blade tip. In an alternative configuration, the blades may have an integrated pressure line positioned to connect a pitot sensor to the blade root. The routing of the pressure line to the blade tip or blade root is determined by the positioning of the transducer. The integrated pressure line may be completely enclosed within the blade such that the pressure line does not extend outside the outer mold line of the blade between the first and second ends. The blades may be fixedly mounted to the core hub using mechanical fasteners, adhesives, or interference fits, or alternatively, they may be formed together with the core hub from a single billet or through additive manufacturing techniques. Multiple blades may be present, extending radially from the core hub. These blades may be evenly distributed radially around the core hub, or irregularly distributed around the core hub. Preferably, there are multiple blades ranging from 5 to 30, more preferably 12 to 20, distributed around the core hub. Each blade may have a cross-sectional thickness ranging from 3 mm to 10 mm. These blades may be substantially collinear with the engine duct, or, in the case of an intricate engine duct, substantially collinear with the direction of the incident airflow. Alternatively, the blades may be offset at a predetermined angle with respect to the incident airflow. The arrangement of each blade relative to the incident airflow will be known to those skilled in the art, depending on the velocity, angle of incidence, and swirl characteristics of the incident airflow. A single Pitot sensor may be provided on at least one blade. A single blade may have multiple Pitot sensors, for example, distributed along the leading edge of the blade. This may provide redundancy when measuring a specific region of the airflow.When multiple blades are provided, there may be more than one pitot sensor; for example, each blade may have at least one pitot sensor. In an alternative arrangement, the multiple pitot sensors may be irregularly distributed among the multiple blades.

[0009] In an alternative configuration, the airflow modification device may feature a honeycomb design. The honeycomb design may comprise multiple cells separated by cell walls arranged to regulate the incoming airflow. The cross-sectional shape of the cells may be square, rectangular, circular, pentagonal, hexagonal, or any other shape with more sides arranged in a mosaic pattern. The cross-sectional width or perimeter of each cell may range from 10 mm to 300 mm, more preferably 75 mm to 125 mm, and more preferably 100 mm. The width of the cell walls is determined by the requirements of the system and is known to those skilled in the art, but it will be understood that the width of the cell walls should be sufficient to incorporate a Pitot sensor at the inlet and to encapsulate the pressure lines within the cell walls.

[0010] Airflow modification devices may be equipped with multiple pitot sensors. This may allow for averaging across the pitot sensors to estimate the aircraft's airspeed more accurately. The average could be the mean, mode, or median of the measurements. Furthermore, if three or more pitot sensors are provided, outlier data can be identified and ignored, for example, by majority vote. Multiple pitot sensors may be distributed on a single blade or cell of the airflow modification device.

[0011] A Pitot sensor may be equipped with a bellmouth orifice. Preferably, unaligned incoming airflow can be captured by a bellmouth orifice, which can improve the accuracy of the Pitot sensor. In one configuration, the cross-sectional diameter of the bellmouth orifice may be equal to the width of the leading edge of the blade or cell wall. This can allow stagnation point pressure to be accurately captured.

[0012] The airflow modification device may include transducers located inside or outside the device. In-device placement can reduce the length of the pressure line, thereby at least partially reducing the delay in acquiring Pitot sensor measurements. The transducers may be mounted inside the blades or cell walls of the airflow modification device. Alternatively, when the device has a spoke design, the transducers may be located at the hub of the device, or within or near the housing of the device.

[0013] The airflow modification device may include a de-icing mechanism. The de-icing mechanism may optionally be an electric heater integrated with this device. In an alternative configuration, the pressure line may be configured to receive an electric current, thereby facilitating de-icing of the pressure line.

[0014] The airflow modification device may include a second sensor selected from the group comprising a static pressure sensor or a temperature sensor. This arrangement may allow for the estimation of further measurements, such as the direction of flow across the engine surface and the swirl within the engine duct. Furthermore, when the temperature sensor is used in conjunction with the de-icing mechanism of the airflow modification device, ice detection can be fully facilitated within the device, where the de-icing mechanism is activated in response to reaching a temperature threshold.

[0015] Airflow changing devices can be made of metal or metal alloy.

[0016] According to a second embodiment, a jet aircraft is provided having an engine duct having an inlet for receiving an incoming airflow and an outlet for directing the airflow to the engine surface, wherein the engine duct is equipped with an airflow changing device according to the first embodiment, the airflow changing device being located directly in front of the engine surface. In one configuration, the engine duct is an intricately shaped engine duct. The jet aircraft may be a military jet, such as a fighter jet. The jet aircraft may be a stealth military aircraft.

[0017] According to a third aspect, a method for using an airflow changing device is provided, which comprises the steps of: providing an airflow changing device according to the first or second aspect in an engine duct; providing an incoming airflow; and measuring the air pressure in the airflow changing device using a Pitot sensor.

[0018] A fourth aspect provides a method for manufacturing an airflow changing device according to the first aspect, the method comprising providing a blade or honeycomb cell wall and forming a channel in the blade or cell wall to form a pressure line.

[0019] In one configuration, the method may involve forming channels by machining or additive manufacturing techniques. Preferably, machining the airflow changing device from a single billet tends to improve the mechanical rigidity of the device. Smooth channels may be machined to form pressure lines using conventional drilling techniques such as gun drilling. Alternatively, additive manufacturing techniques may allow the introduction of internal geometric shapes for the pitot sensor and pressure lines into the airflow changing device that would not be possible using conventional machining techniques.

[0020] Next, embodiments of the present invention will be described simply as examples with reference to the drawings. [Brief explanation of the drawing]

[0021] [Figure 1] Figure 1 shows an example of prior art in which a pitot sensor is mounted on the outside of an aircraft. [Figure 2] Figure 2 shows an example of a schematic diagram of an engine duct in an aircraft equipped with an airflow modification device according to the present invention. [Figure 3] Figure 3 shows a schematic diagram of the engine duct shown in Figure 2. [Figure 4a] Figure 4a shows an airflow modification device for spoke design. [Figure 4b] Figure 4b shows an airflow modification device for spoke design. [Figure 5] Figure 5 shows a cross-sectional view of the blade of the airflow modification device. [Figure 6] Figure 6 shows the airflow modification device of the honeycomb design.

Best Mode for Carrying Out the Invention

[0022] Figure 1 shows an example of the prior art. An aircraft 100, in this example a fighter jet, is shown, and includes a plurality of pitot sensors 102 attached to the underside of the nose of the aircraft 100. In an alternative arrangement, the pitot sensor(s) 102 may be attached on the tip of the nose of the aircraft, or on the leading edge of the aircraft extending into the free airflow, such as on the wing. The pitot sensors 102 are used to measure the aircraft's airspeed relative to the air, and optionally are configured to calculate other aircraft parameters such as static pressure, angle of attack, and sideslip. When the pitot sensors 102 are attached outside the aircraft 100, they are vulnerable to damage by inadvertent contact and blockage by nesting animals or debris. Further, such protrusions increase the radar cross-section of the aircraft, which is undesirable in stealth aircraft.

[0023] Figure 2 shows an example of a schematic view of an engine duct 204 in an aircraft 200 including an airflow modification device 206 according to the present invention. In this example, the aircraft includes an internal engine 208 having an engine face 210 housed within the upper structure of the aircraft 200. To direct the incoming airflow 212 to the engine face 210 of the engine, the engine duct 204 has an inlet towards the front of the aircraft to direct air internally in the upper structure of the aircraft 200 to the engine face 210. The incoming airflow 212 is a substantially laminar fluid. When the incoming airflow 212 enters the engine duct 204, turbulence occurs, which causes the cross-sectional flow at any point within the engine duct 204 to be circumferentially asymmetric. To at least partially condition the flow and restore the flow to a laminar state at the engine face 210, the airflow modification device 206 is provided immediately upstream of the engine face 210. The airflow modification device 206 comprises a geometric shape configured to condition the flow.

[0024] Figure 3 shows the engine duct of Figure 2 in more detail. When the incoming air flow 212 enters the engine duct 204, the flow substantially transitions from laminar to turbulent, as indicated by the flow arrow 214. As the turbulent air flow passes through the inlet of the air flow modification device, the flow is conditioned and at least partially restored to laminar flow at the engine face 210.

[0025] Next, the air flow modification device will be described in more detail. Figures 4a and 4b show an example of a spoke-designed air flow modification device 406. Figure 4a shows a side view of the air flow modification device 406, and Figure 4b shows a cross-sectional view along axis A of Figure 4a. In Figure 4a, the air flow modification device 406 includes an inlet 416, an outlet 418, and a flow path 420 extending from the inlet 416 to the outlet 418. In Figure 4b, the air flow modification device 406 includes a core hub 422 and eight blades 424 radially extending from the core hub 422 in an equiangular arrangement. Each blade 424 includes a blade root portion 426 located proximal to the core hub 422 and a blade tip portion 428 at the distal end of each blade 424. In this arrangement, the blade tip portion 428 of each of the blades 424 is surrounded by a housing 430. In this arrangement, the core hub 422, the blades 424, and the housing 430 are made from a single body manufactured, for example, by additive manufacturing, but in an alternative arrangement, they can be made from individual components that are mechanically joined, chemically joined, or have joining geometries that allow for interference fits. In this arrangement, one of the blades 425 includes an integral pitot sensor 402, which can be seen more clearly in Figure 5.

[0026] Figure 5 shows a cross-sectional view of the blade 424 of Figure 4b along axis B. In particular, the blade 424 is shown with a Pitot sensor 502 integrated with the blade 424 of the airflow changing device. The Pitot sensor 502 has a bell mouth orifice. Also shown is a pressure line 534 connected to the Pitot sensor 502 at a first end and connected to a transducer 536 at a second end. The pressure line 534 is completely enclosed within the blade 424 of the airflow changing device between the first and second ends. During use, the incident airflow enters the Pitot sensor 502 and remains stationary in the pressure line 534. The transducer 536 is configured to measure the stagnant pressure in the pressure line 534, which can then be used to estimate the airvelocity of the incident air 512. In this configuration, the transducer 536 is shown as being outside the blade 424, proximal to the blade root 426; however, the transducer 536 may alternatively be located inside the blade 424.

[0027] Figure 6 shows an alternative arrangement of the airflow changing device 606 according to the present invention. In this example, the airflow changing device 606 is as shown in Figure 4(406), but instead of the core hub 422 and blades 424, the airflow changing device 606 has a honeycomb design comprising a plurality of hexagonal cells 638, each cell separated by a cell wall 640. The cells 638 are bounded by a housing 630 as shown in Figure 4. In this example, a plurality of pitot sensors 602 are provided, which are integrated with the cell wall 640 of the airflow changing device 606. The pitot sensors 602 are formed within the cell wall 640 (not to scale). Each pitot sensor 602 has its own pressure line (not shown), which is completely enclosed within the cell wall 640.

Claims

1. A jet aircraft comprising an engine duct having an inlet for receiving an incoming airflow and an outlet for directing the airflow to the engine surface, wherein the engine duct comprises an airflow modification device located directly in front of the engine surface, and the airflow modification device is Inlet and Outlet and A flow path extending from the inlet to the outlet, Equipped with, Here, the device is positioned to receive the incoming airflow, The device is configured to at least partially regulate the airflow in the flow path in order to improve the ordering of the incoming airflow at the engine surface. The aforementioned airflow changing device is At least one pitot sensor, which is integrated with the device and located at the inlet, A pressure line having a first end and a second end, wherein the first end is connected to the Pitot sensor and the second end is configured to be connected to a transducer, Furthermore, Herein, the pressure line is completely enclosed within the device, in a jet aircraft.

2. The jet aircraft according to claim 1, wherein the device comprises a spoke design or a honeycomb design.

3. The device described above, Core hub and, From there, at least one blade extends radially, It has a spoke design that includes The jet aircraft according to claim 2, wherein each blade comprises a blade root located near the core hub and a blade tip located at the distal end, and the integrated pressure line is arranged to connect the pitot sensor to the blade root or tip.

4. The jet aircraft according to claim 3, wherein the blade has a cross-sectional thickness in the range of 3 mm to 10 mm.

5. A jet aircraft according to any one of claims 1 to 4, wherein a plurality of pitot sensors are provided.

6. The jet aircraft according to any one of claims 1 to 5, wherein the pitot sensor is provided with a bellmouth orifice.

7. A jet aircraft according to any one of claims 1 to 6, comprising a transducer located within the aforementioned device.

8. The jet aircraft according to any one of claims 1 to 7, wherein the device comprises an ice removal mechanism.

9. The jet aircraft according to any one of claims 1 to 8, wherein the device comprises a second sensor selected from the group comprising a static pressure sensor or a temperature sensor.

10. The aircraft according to any one of claims 1 to 9, wherein the engine duct is an intricately designed engine duct.

11. A method for using a jet airflow modification device according to any one of claims 1 to 10, wherein the method is: The steps of providing an incoming airflow, The steps include: measuring the air pressure in the airflow changing device using the Pitot sensor; A method that includes [a certain feature].

12. A method for manufacturing a jet airflow modification device according to any one of claims 1 to 10, wherein the method is: By providing a blade or honeycomb cell wall, To form a pressure line, a channel is formed in the blade or cell wall, A method that includes [a certain feature].

13. The method according to claim 12, further comprising forming the channel by machining or additive manufacturing techniques.

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