An intelligent flow control method and system for air-breathing high-speed aircraft

Abstract

The present invention discloses an intelligent flow control method and system for an air-breathing high-speed aircraft, relating to the field of flow control of aircraft aerodynamic performance, including: S1, arranging a suction module on the compression surface of the aircraft's air inlet and / or at a location within the aircraft that is prone to flow separation; S2, arranging a blowing module in an area on the aircraft's outer surface where drag reduction is required; S3, using a control system to control the air source obtained by a driving module from the suction module and delivering it to the blowing module through a regulating valve. The present invention provides an intelligent flow control method for an air-breathing high-speed aircraft, which achieves air source-free flow control of the aircraft and can simultaneously achieve flow control of both suction and blowing, that is, improving the aerodynamic performance of the air inlet through suction and improving the aerodynamic performance of the aircraft's outer surface through blowing, thereby reducing drag.

Description

Technical Field

[0001] The present invention relates to the field of flow control for aerodynamic performance of aircraft, and more particularly to an intelligent flow control method and system for air-breathing high-speed aircraft. Background Art

[0002] Air-breathing high-speed aircraft are typically powered by scramjets or ramjets, capable of hypersonic cruise and strong maneuverability, meeting the requirements of long-range and wide-speed flight. The inlet, a key component of air-breathing combined-cycle engines, decelerates and boosts the airflow by compressing it, providing oxidizer for the combustion chamber. Designing a high-quality, high-flow hypersonic inlet is a primary task in engine design.

[0003] Air-breathing high-speed aircraft experience complex shock wave / boundary layer interactions, which induce boundary layer separation and form a large separation bubble. When the size of the separation bubble exceeds the spatial dimensions of the hypersonic inlet to a certain extent, the inlet flow capacity decreases, the flow capture coefficient significantly reduces, the inlet wave system and flow field structure are destroyed, the inlet total pressure recovery and flow field uniformity decrease, and the inlet does not start. In the non-start mode, the throat will be blocked, causing surge, and the time-averaged pressure will increase significantly. The instantaneous ballast and aerodynamic drag can reach 20 times and 5 times the conventional starting values, respectively, causing inlet structural deformation and leading to flight accidents.

[0004] Flow control involves actively or passively interfering with the flow field by changing fluid parameters such as velocity, pressure, temperature, and density, thereby optimizing fluid performance or reducing fluid drag. Flow control plays a crucial role in improving an aircraft's lift-to-drag ratio, enhancing inlet starting performance, and reducing noise and vibration.

[0005] Currently, commonly used active flow control methods include boundary layer suction, boundary layer blowing, energy deposition, and magnetohydrodynamic control. Boundary layer suction, among other methods, has been extensively documented and demonstrated to remove low-speed gas from the boundary layer, thereby eliminating or reducing the separation zone. Similarly, numerous studies have demonstrated that boundary layer blowing can alter the velocity profile of the fluid within the boundary layer, thereby reducing frictional resistance. This effect is particularly pronounced in turbulent boundary layers.

[0006] At present, these flow control methods are still difficult to apply to air-breathing high-speed aircraft. The main technical problems include: the problem of gas source processing after boundary layer suction, the boundary layer blowing requires carrying additional gas source, and the problem of limited gas source. Summary of the Invention

[0007] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0008] To achieve these objects and other advantages of the present invention, there is provided an intelligent flow control method for an air-breathing high-speed aircraft, comprising:

[0009] S1. Arrange a suction module on the compression surface of the aircraft inlet and / or at a location inside the aircraft that is prone to flow separation;

[0010] S2. Arrange an air blowing module on the area of the aircraft outer surface where drag reduction is required;

[0011] S3, using the control system, the air source obtained by the driving module from the suction module is delivered to the blowing module through the regulating valve;

[0012] The control system detects the pressure change in the area where the suction module is located in real time through the sensor module, so as to adjust the suction volume by analyzing the state of the separation zone inside the aircraft;

[0013] The control system detects the flow rate and pressure changes in the area where the air blowing module is located in real time through the sensor module, so as to control the air blowing volume by analyzing the flow state of the outer surface of the aircraft.

[0014] A system, applied to an intelligent flow control method for an air-breathing high-speed aircraft, comprising:

[0015] flow control subsystem;

[0016] a control module coordinated with the flow control subsystem;

[0017] a sensor module for obtaining status information of the flow control subsystem;

[0018] a drive module that is in communication with the control module to switch the working state of the flow control subsystem;

[0019] Wherein, the flow control subsystem includes: a suction module and a blowing module.

[0020] Preferably, the suction module is configured to employ a suction block;

[0021] The suction block is provided with a plurality of suction holes on the inner flow side, and a gas collecting cavity connected with the suction holes is provided on the other side.

[0022] Preferably, the suction hole is a cylindrical hole with a hole diameter of 1 mm.

[0023] Preferably, the blowing module is configured to adopt a blowing block;

[0024] The blowing block is provided with a plurality of blowing holes on the inner flow side, and a blowing cavity communicating with the blowing holes is provided on the other side.

[0025] Preferably, the blowing hole is a cylindrical hole or a slot-shaped hole with a hole diameter or slot width of 1 mm;

[0026] Wherein, each blowing hole has a predetermined inclination angle designed along the flow direction, and each blowing hole is arranged non-uniformly on the surface of the blowing block.

[0027] Preferably, the sensor module includes:

[0028] Pressure sensor I, which is provided on the inner wall surface area upstream and downstream of the suction module and is used to feed back the pressure changes at the corresponding positions to the control system in real time;

[0029] It is installed on the blowing cavity and connected to the regulating valve in the driving module to feed back the blowing flow information to the flow sensor of the control system in real time;

[0030] Pressure sensors II are located on the outer wall of the upstream and downstream areas of the air blowing module and are used to provide real-time feedback of pressure changes at the corresponding positions to the control system.

[0031] Preferably, the driving module includes:

[0032] An air supply pipeline connecting the suction module and the blowing module;

[0033] A driver provided on the air supply pipeline for sucking gas from the suction module;

[0034] A compressed gas tank installed on the air supply pipeline for temporarily storing the gas sucked from the driver;

[0035] A regulating valve installed on the gas supply pipeline to control the gas flow output from the compressed gas tank;

[0036] A gas flow meter installed on the gas supply pipeline to measure the gas flow after the regulating valve is adjusted;

[0037] Wherein, the regulating valve, driver and gas flow meter are all communicatively connected with the controller.

[0038] The present invention has at least the following beneficial effects:

[0039] (1) The method and system provided by the present invention can simultaneously realize the flow control of suction and blowing, improve the aerodynamic performance of the air inlet by suction, and improve the aerodynamic performance of the outer surface of the aircraft by blowing, thereby reducing the drag.

[0040] (2) The method and system provided by the present invention get rid of the problem of the need to carry a gas source and the limited gas source in the traditional flow control process. This method can ensure that the aircraft can continuously inhale and discharge gas over a long period of time and a wide speed range, and is sustainable.

[0041] (3) The method and system provided by the present invention can achieve intelligent flow control effects by monitoring the flow parameters of the air inlet and the aircraft surface in real time, and perform real-time online control of the driver and the regulating valve according to the changes in the flow on the internal and external surfaces, thereby ensuring that the flow control is maintained in the optimal performance state.

[0042] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A schematic diagram of the coordination of the main components of an air-breathing high-speed aircraft and its intelligent flow control system;

[0044] Figure 2 A top view of the suction module of the present invention;

[0045] Figure 3 is a cross-sectional view of the suction module of the present invention;

[0046] Figure 4 A top view of the air blowing module of the present invention;

[0047] Figure 5 is a cross-sectional view of the air blowing module of the present invention;

[0048] Figure 6 This is a workflow diagram of the intelligent flow control system of the present invention;

[0049] Figure 7 A schematic diagram of the drag reduction area on one of the surfaces of an aircraft;

[0050] Figure 8 A schematic diagram of the uniform and non-uniform distribution of blowing holes with the same number is given;

[0051] Figure 9 Schematic diagram of the wall model without blowing holes;

[0052] Figure 10 Schematic diagram of the wall-blowing model with evenly distributed blowing holes;

[0053] Figure 11 Schematic diagram of a wall-surface air blowing model with unevenly distributed air holes obtained by the method of the present invention;

[0054] Figure 12 To adopt Figures 9-11 Schematic diagram of the distribution of surface friction coefficient along the flow direction for the three types of models;

[0055] Among them, the inlet compression surface-1, separation zone-2, shock wave structure-3, inlet inner compression surface-4, inner flow channel separation zone-5, combustion chamber-6, tail nozzle-7, fuselage-8, blowing module-9, sensor module-10, control module-11, drive module-12, suction module-13, suction hole-14, boundary layer-15, gas collecting cavity-16, blowing hole-17, exhaust cavity-18, drive-19, compressed gas tank-20, regulating valve-21, pressure sensor I-22, flow sensor-23, pressure sensor II-24, vertical line-25, baseline j -26, Baseline j Starting position -27, baseline j The terminal position-28, the surface area of the aircraft-29, and the boundary layer of the outer surface of the aircraft-30. DETAILED DESCRIPTION

[0056] The present invention will be described in further detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0057] like Figure 1 As shown ( Figure 1 Where Ma is the Mach number), a conventional air-breathing high-speed aircraft mainly includes: an air inlet, a combustion chamber 6, a tail nozzle 7, and an airframe 8. When a conventional air-breathing high-speed aircraft operates under design conditions, its speed reaches supersonic or even hypersonic speeds. Usually, a shock wave structure 3 (also called an aircraft wave structure) is generated at the aircraft head, the air inlet compression surface 1, and other parts. After the airflow passes through the shock wave structure 3, the speed decreases and the pressure increases. At the forebody compression surface, the airflow boundary layer gradually thickens along the flow direction. At the same time, the shock wave structure 3 causes the downstream flow pressure to rise, resulting in a separation zone 2 locally on the compression surface ( Figure 2 The red area marked 2 in the figure) will affect the captured flow of the inlet, and measures need to be taken to eliminate or reduce the separation area. Similarly, on the compression surface 4 of the inlet (also called the inlet inner flow channel), there is an interaction between the shock wave train and the inner flow channel boundary layer, which will also cause the corresponding inner flow channel separation area 5 ( Figure 2 The existence of these separation zones will affect the starting performance of the intake duct, so measures need to be taken to eliminate or reduce the separation zones.

[0058] The present invention, however, is to provide an intelligent flow control system on the main components of a conventional air-breathing high-speed aircraft, including a flow control subsystem;

[0059] A control module 11 coordinated with the flow control subsystem;

[0060] A sensor module 10 for acquiring status information of the flow control subsystem;

[0061] A drive module 12 in communication with the control module to switch the working state of the flow control subsystem;

[0062] The flow control subsystem includes: a suction module 13 and an air blowing module 9 .

[0063] In actual application, the suction module is arranged on the compression surface and internal part of the aircraft inlet, which are prone to cause flow separation, to suck the low-speed gas in the separation area to eliminate or reduce the separation area.

[0064] In actual application, the air blowing module is arranged on the outer surface of the aircraft (fuselage, wings, etc.), and by spraying gas outward, the velocity profile of the outer flow boundary layer is changed to reduce frictional resistance.

[0065] Furthermore, if Figure 2-Figure 3 As shown, a plurality of suction holes 14 are provided on the suction module 13 (which can be directly processed on the surface of the aircraft as needed). The number of the suction holes 14 can be reasonably designed according to the size of the separation area and the density of the holes;

[0066] The suction hole 14 is a cylindrical hole, and the hole diameter is generally 1 mm.

[0067] The suction hole 14 is formed by opening a hole on the wall of the separation zone. A gas collecting chamber 16 is provided below the suction hole 14 for collecting the gas sucked from the boundary layer 15 .

[0068] Furthermore, if Figure 4-Figure 5 As shown, the blowing module 9 (which can be directly processed on the aircraft surface as needed) is provided with a plurality of blowing holes 17. The number of the blowing holes 17 can be reasonably designed according to the size of the drag reduction area on the outer surface of the aircraft and the density of the holes;

[0069] The blowholes 17 are cylindrical or slot-shaped, typically with a diameter or width of 1 mm. They can be designed with a certain inclination angle along the flow direction. These holes are formed by opening a hole in the outer surface of the aircraft. An exhaust cavity 18 is located below the holes. The air blowing affects the velocity profile of the boundary layer 30 on the outer surface of the aircraft, thereby reducing drag.

[0070] It should be noted that in actual applications, the air holes can be arranged according to the distribution of friction resistance on the aircraft surface, with equal spacing differences in friction resistance along the flow direction. In other words, a non-uniform layout can be set to achieve the best drag reduction effect. Specifically, the non-uniform layout of air holes is implemented as follows:

[0071] S1. First, for the aircraft that needs to reduce drag, the friction coefficient of the aircraft surface is obtained through experimental measurement, numerical simulation calculation or empirical estimation. It is defined as follows:

[0072] (1)

[0073] In the above formula, C f is the friction coefficient (abbreviated as friction coefficient), is the wall shear stress, and are the density and velocity of the reference flow, respectively. The wall shear stress can be obtained through experimental measurement, numerical simulation calculation or empirical estimation.

[0074] S2. Analyze the drag reduction requirements of the entire aircraft surface based on the obtained friction coefficient, determine the area with the largest friction distribution value of the entire aircraft, or determine the aircraft surface area requiring drag reduction based on aerodynamic analysis 29, such as Figure 7 The figure shows the drag reduction area of a certain surface of the aircraft. On the aircraft surface where multiple air blowing holes need to be arranged, the layout baseline of the wall air blowing holes is divided along the flow direction. Select any baseline j ( Figure 7 mid-baseline j The mark is 26, and the vertical line is 25, which is used to indicate the difference between the surface and the baseline. j Vertical auxiliary line), its horizontal corresponding physical coordinate is y j , now given in the baseline j The porous distribution design method above is used, and the other baselines refer to this method.

[0075] S3. Extract baseline j Friction coefficient on , which is distributed along the flow direction as Figure 2 As shown, take the starting point and end point The friction coefficients are and , take the number of blowing holes on the wall as N (The figure takes N =5 as an example), calculate the friction coefficient difference :

[0076] (2)

[0077] S4. Determine the position of each wall blowing hole according to the difference in friction coefficient. The specific method is based on formula (2), and the first i The friction coefficient at each position is:

[0078] (3)

[0079] S5. According to iPosition friction coefficient , combined with S4 to obtain the friction coefficient distribution , calculate the baseline j The upper friction coefficient is Corresponding flow direction physical coordinates x i , x i Represents the horizontal axis. It should be noted here that although the friction coefficient of the entire aircraft along the flow direction is not monotonically increasing or monotonically decreasing, due to the existence of factors such as boundary layer transition, the wall friction coefficient after the flow on the aircraft surface transitions to turbulent flow is much higher than the laminar flow friction coefficient, so wall blowing has the best drag reduction effect on the turbulent boundary layer. After the transition to turbulence, except for shock wave interference or other special factors, the turbulent boundary value friction must change monotonically along the flow direction. In addition, since the wall blowing holes will cause certain damage to the surface structure, it is generally only for local areas to reduce drag. The area of this local area is relatively small, so it can be considered that the friction coefficient changes monotonically with the flow direction. In summary, due to the above analysis, The x-coordinate is monotonic along the flow direction, then The value corresponds to the x coordinate one by one, determining a The value of x can be determined by measuring.

[0080] S6. On the baseline j, according to the number N of the wall blowing holes, the position of each wall blowing hole can be known from the above steps as follows ( x i , y j ),Right now Figure 8 Mark 27 is the baseline j The starting position, marker 28 is the baseline j The end position of Figure 8 middle represents the difference in friction coefficient, Represents the distance difference along the flow direction.

[0081] In addition, in order to give a difference from the traditional design method, under the condition of ensuring the same number of wall blowing holes, Figure 8 Also given at baseline j In the figure above, A1, A2, and A3 illustrate a uniform distribution of wall-blowing holes, while B1, B2, and B3 illustrate a non-uniform distribution of wall-blowing holes obtained using the method of the present invention. It can be seen that the wall-blowing hole arrangements obtained by the two methods are completely different, and therefore the corresponding drag reduction effects are inevitably different. The following examples demonstrate that the design method of the present invention has a superior drag reduction effect.

[0082] S7. The positions of other baseline wall air blowing holes refer to steps S3 to S6. The above method can be used to determine the design method of the wall air blowing holes for the entire drag reduction area.

[0083] Example:

[0084] For leading edge angle θ =22.5°, and the curvature of the upper surface of the wedge gradually decreases and the curvature at the end is zero. Figure 9 The wall model without blowing holes is shown in Figure 10 The wall blowing model with evenly distributed blowing holes is shown in Figure 11 The wall-blowing model with a non-uniformly distributed blowhole arrangement, obtained using the design method of the present invention, is shown. To demonstrate the effectiveness of the present invention's design, computational fluid dynamics (CFD) was used to simulate the flow field, with an incoming flow Mach number of 5 and a wall-blowing velocity set to 1% of the incoming flow velocity.

[0085] based on Figure 12 The distribution diagram of surface friction coefficient along the flow direction of the three types of models is given ( Figure 12 middle C f (where x / L represents the dimensionless distance along the flow direction, and x is the friction coefficient.) It can be seen that both porous arrangements with wall air blowing effectively reduce wall friction compared to those without wall air blowing. Furthermore, compared to the uniformly distributed porous arrangement, the present invention's arrangement exhibits lower friction across most areas, except for some areas where friction is higher. This demonstrates a significant improvement in the overall drag reduction effect of the porous arrangement.

[0086] Furthermore, if Figure 1 、 Figure 6 As shown (where Figure 6 The solid line with an arrow is the direction of airflow, the dashed line with an arrow is the direction of sensor detection data feedback, and the dotted line with an arrow is the direction in which the controller sends a control signal). The sensor module 10 (including an inner surface pressure sensor and an outer surface pressure sensor) is arranged in the upstream and downstream areas of the suction module and the blowing module, and is responsible for monitoring the dynamic changes of pressure at the corresponding positions and feeding back the pressure information to the control system in real time. Specifically, the pressure sensor I 22 is arranged in the inner wall area upstream and downstream of the suction module, and is used to feed back the pressure changes at the corresponding positions to the control system in real time.

[0087] It is installed on the blowing cavity and connected to the regulating valve in the driving module to feed back the blowing flow information to the flow sensor 23 of the control system in real time;

[0088] Pressure sensors II 24 are provided in the outer wall areas upstream and downstream of the blowing module to provide real-time feedback of pressure changes at corresponding positions to the control system.

[0089] Furthermore, if Figure 6 As shown, the driving module includes a driver 19, a compressed gas tank 20 and a regulating valve 21. The driver is responsible for sucking gas from the suction module to the compression tank, and the regulating valve is responsible for controlling the discharge of compressed gas to the blowing module. At the same time, as needed, a gas flow meter can be set to measure the gas flow flowing through the pipeline after the regulating valve is adjusted.

[0090] Furthermore, if Figure 6 As shown, the control module 11 is the control unit of the entire intelligent flow control. It controls the suction power of the driver by analyzing the pressure changes of the suction module, controls the size of the regulating valve switch by analyzing the pressure changes in the blowing area, and provides feedback by monitoring the flow sensor.

[0091] Furthermore, if Figure 6 As shown, the control module 11 (also called the controller) is responsible for the overall flow control operation. The controller is pre-installed with an intelligent control algorithm. It receives information from sensors in the suction module area, analyzes the state of the separation zone, and controls the power of the driver to adjust the suction effect. The controller also receives information from sensors in the air blowing module area, analyzes the external surface flow state, and controls the size of the regulating valve to adjust the air blowing effect.

[0092] The present invention intends to combine the two flow control technologies of suction and blowing. By introducing an intelligent control system, it can control the size of the separation area of the air intake duct of the air-breathing aircraft, improve the starting performance of the air intake duct, and at the same time achieve the effect of reducing the drag of the outer surface of the aircraft. The air source obtained by suction control is used for blowing control, which solves the air source problem of flow control. The control system realizes closed-loop control and is sustainable.

[0093] The above solution is only an illustration of a preferred embodiment, but is not limited thereto. When implementing the present invention, appropriate replacements and / or modifications can be made according to user needs.

[0094] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and exemplary embodiments. They can be applied to a variety of fields suitable for the present invention. Further modifications will be readily apparent to those skilled in the art. Therefore, the present invention is not limited to the specific details and illustrations shown and described herein without departing from the general concept defined by the claims and their equivalents.

Claims

1. An intelligent flow control method for an air-breathing high-speed aircraft, characterized in that: include: S1. Arrange a suction module on the compression surface of the aircraft inlet and / or at a location inside the aircraft that is prone to flow separation; S2. Arrange an air blowing module on the area of the aircraft outer surface where drag reduction is required; S3, using the control system, the air source obtained by the driving module from the suction module is delivered to the blowing module through the regulating valve; The control system detects the pressure change in the area where the suction module is located in real time through the sensor module, so as to adjust the suction volume by analyzing the state of the separation zone inside the aircraft; The control system detects the flow rate and pressure changes in the area where the air blowing module is located in real time through the sensor module, so as to control the air blowing volume by analyzing the flow state of the outer surface of the aircraft.

2. A system, applied to the intelligent flow control method for an air-breathing high-speed aircraft as claimed in claim 1, characterized in that: include: flow control subsystem; a control module coordinated with the flow control subsystem; a sensor module for obtaining status information of the flow control subsystem; a drive module that is in communication with the control module to switch the working state of the flow control subsystem; Wherein, the flow control subsystem includes: a suction module and a blowing module.

3. The system according to claim 2, wherein: The suction module is configured to employ a suction block; The suction block is provided with a plurality of suction holes on the inner flow side, and a gas collecting cavity connected with the suction holes is provided on the other side.

4. The system according to claim 3, wherein: The suction hole is a cylindrical hole with a hole diameter of 1 mm.

5. The system according to claim 2, wherein: The blowing module is configured to employ a blowing block; The blowing block is provided with a plurality of blowing holes on the inner flow side, and a blowing cavity communicating with the blowing holes is provided on the other side.

6. The system according to claim 5, wherein: The blowing hole is a cylindrical hole or a slot-shaped hole with a hole diameter or slot width of 1 mm; Wherein, each blowing hole has a predetermined inclination angle designed along the flow direction, and each blowing hole is arranged non-uniformly on the surface of the blowing block.

7. The system according to claim 2, wherein: The sensor module includes: Pressure sensor I, which is provided on the inner wall surface area upstream and downstream of the suction module and is used to feed back the pressure changes at the corresponding positions to the control system in real time; It is installed on the blowing cavity and connected to the regulating valve in the driving module to feed back the blowing flow information to the flow sensor of the control system in real time; Pressure sensors II are located on the outer wall of the upstream and downstream areas of the air blowing module and are used to provide real-time feedback of pressure changes at the corresponding positions to the control system.

8. The system according to claim 2, wherein: The driving module includes: An air supply pipeline connecting the suction module and the blowing module; A driver provided on the air supply pipeline for sucking gas from the suction module; A compressed gas tank installed on the air supply pipeline for temporarily storing the gas sucked from the driver; A regulating valve installed on the gas supply pipeline to control the gas flow output from the compressed gas tank; A gas flow meter installed on the gas supply pipeline to measure the gas flow after the regulating valve is adjusted; Wherein, the regulating valve, driver and gas flow meter are all communicatively connected with the controller.

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