Intelligent plasma flow control device and method for incident shock wave boundary layer interference

Abstract

The invention provides an intelligent plasma flow control device and method for incident shock wave boundary layer interference, and relates to the technical field of flow control. The device comprises a controller, a high-voltage pulse power supply, a flat plate, a plasma synthetic jet exciter, a first wall surface hot line module, a second wall surface hot line module, a shock wave generator, a truss and a support, and the plasma synthetic jet exciter, the first wall surface hot line module and the second wall surface hot line module are sequentially installed on the flat plate at intervals in the direction from upstream to downstream. The truss is vertically installed on the support, the shock wave generator is connected with the support, the upstream tail end of the shock wave generator is provided with a first dip angle structure, and the shock wave generator is located above the first wall surface hot wire module and the second wall surface hot wire module; the exciter is electrically connected with the high-voltage pulse power supply, and the controller is electrically connected with the high-voltage pulse power supply, the first wall surface hot wire module and the second wall surface hot wire module. The method has the advantages of better robustness and higher adaptability.

Description

Technical Field

[0001] The present application relates to the technical field of flow control, and more specifically, to an intelligent plasma flow control device and method for incident shock wave boundary layer interference. Background Art

[0002] Shock wave / boundary layer interference is an adverse phenomenon in supersonic flight, which widely exists on the surface of aircraft and inside the intake system. When the flight speed exceeds Mach 1, the oncoming flow inevitably encounters irregular objects such as corners and wedges on the aircraft body. The oncoming flow cannot pass through these areas smoothly, so the front airflow is blocked, the rear airflow speed remains unchanged, causing compression of the gas in this area, and thus forming multiple compression waves. Due to the induction of the pressure gradient, the multiple compression waves combine into one, which is called a shock wave. The shock wave causes a great change in air pressure, and often has a strong interference effect with other flow field structures, having a profound impact on the supersonic flow field.

[0003] On the one hand, the strong adverse pressure gradient induced by the shock wave will cause the separation of the boundary layer flow, resulting in a decrease in the total pressure recovery coefficient and the flow coefficient of the intake system; on the other hand, the low-frequency oscillation caused by the interference between the shock wave and the boundary layer will cause additional pulsating pressure loads on the aircraft body structure, causing resonance and fatigue, etc.

[0004] Currently, the methods for suppressing shock wave / boundary layer interference mainly include vortex generators, bump deformation, wall suction, and plasma excitation, etc. Vortex generators and bump deformation both belong to passive flow control methods. Their basic principle is to induce streamwise vortices to promote the mixing inside the boundary layer, thereby improving the ability of the boundary layer to resist the adverse pressure gradient and achieving the purpose of weakening the flow separation caused by the shock wave. Although these two passive control methods are effective, they will cause additional drag when there is no shock wave / boundary layer interference. Wall suction, as an active flow control method, can be freely switched according to the flight state, with stronger adaptability and no additional drag. However, in order to achieve suction, it is also necessary to arrange components such as air ducts, suction pumps, and valves inside the aircraft, increasing the structural weight coefficient of the aircraft.

[0005] Plasma aerodynamic excitation is a new type of active flow control method. It applies a controllable disturbance to the flow field through the directional movement of plasma under the action of an electromagnetic field and heat release during discharge, having the advantages of simple structure, fast response speed, and high frequency response. However, the existing plasma aerodynamic excitation generally operates in an open-loop state, and the optimal excitation voltage and frequency need to be selected through a large number of debuggings, which is time-consuming and laborious. Moreover, due to open-loop control, once the flight state changes, the excitation voltage and frequency cannot be adjusted adaptively, having problems of poor robustness and insufficient adaptability. Summary of the Invention

[0006] The purpose of this application is to provide an intelligent plasma flow control device and method for incident shock wave boundary layer interference, so as to solve the problems of poor robustness and insufficient adaptability of plasma aerodynamic excitation in the prior art.

[0007] In order to achieve the above object, the technical solutions adopted in the embodiments of this application are as follows: On the one hand, the embodiments of this application provide an intelligent plasma flow control device for incident shock wave boundary layer interference. The device includes a controller, a high-voltage pulse power supply, a flat plate, a plasma synthetic jet actuator, a first wall hot-wire module, a second wall hot-wire module, a shock wave generator, a truss, and a bracket. The bracket is connected to the flat plate. The plasma synthetic jet actuator, the first wall hot-wire module, and the second wall hot-wire module are sequentially and spaced apart along the upstream to downstream direction and installed on the flat plate. The truss is vertically installed on the bracket. The shock wave generator is connected to the bracket. A first inclination structure is provided at the upstream end of the shock wave generator, and the shock wave generator is located above the first wall hot-wire module and the second wall hot-wire module; The plasma synthetic jet actuator is electrically connected to the high-voltage pulse power supply. The controller is electrically connected to the high-voltage pulse power supply, the first wall hot-wire module, and the second wall hot-wire module respectively; wherein, When in a supersonic flight environment, the air flow flows from upstream to downstream. The shock wave generator is used to generate an incident oblique shock wave and strike the area between the first wall hot-wire module and the second wall hot-wire module; The plasma synthetic jet actuator is used to form a jet cycle to suppress shock wave boundary layer interference; The first wall hot-wire module and the second wall hot-wire module are used to obtain the air state at the corresponding positions; The controller is used to adjust the supply voltage and / or supply frequency of the high-voltage pulse power supply according to the air state, so as to adjust the discharge voltage and / or discharge frequency of the plasma synthetic jet actuator.

[0008] Optionally, a second inclination structure is provided at the upstream end of the flat plate, and a third inclination structure is provided at the downstream end of the shock wave generator, and the inclination angles of the second inclination structure and the third inclination structure are the same.

[0009] Optionally, the inclination angle of the first inclination structure is 5° to 20°.

[0010] Optionally, a long strip-shaped installation groove is provided on the side of the shock wave generator. The length of the installation groove is greater than the length of the truss. The truss is installed at any position of the installation groove and fixed by a fixing member.

[0011] Optionally, the plasma synthetic jet actuator includes a cathode, an anode, a separation boss, and a main body. The main body is provided with a jet cavity. Each cathode and one anode form an electrode pair and are arranged in the jet cavity. The separation boss is located between the cathode and the anode of each electrode pair. The cathode and the anode of each electrode pair are both connected to the high-voltage pulse power supply.

[0012] Optionally, the distance between two adjacent electrode pairs is set to 3 - 5 mm.

[0013] Optionally, the first wall hot-wire module and the second wall hot-wire module have the same structure. The first wall hot-wire module includes a hot-wire probe, a setscrew, a fastening screw, and a base body. The base body is arranged in an inverted T-shaped structure. An installation hole is provided at the top of the base body. The hot-wire probe is installed in the installation hole and fixed by the setscrew. Installation holes are provided on both sides of the base body. The fastening screw is located in the installation hole and fixes the base body to the flat plate.

[0014] Optionally, the plasma synthetic jet actuator, the first wall hot-wire module, and the second wall hot-wire module are all installed at the bottom of the flat plate, and the surfaces of the plasma synthetic jet actuator, the first wall hot-wire module, and the second wall hot-wire module are flush with the surface of the bracket.

[0015] On the other hand, the embodiment of the present application also provides an intelligent plasma flow control method for incident shock wave boundary layer interference, which is applied to the intelligent plasma flow control device for incident shock wave boundary layer interference described above. The method includes: Controlling the supply voltage and / or supply frequency of the high-voltage pulse power supply to make the plasma synthetic jet actuator work; Obtaining the air state transmitted by the first wall hot-wire module and the second wall hot-wire module; Based on the reinforcement learning model and the air state, adjusting the supply voltage and / or supply frequency of the high-voltage pulse power supply until the shock wave boundary layer interference is completely suppressed.

[0016] Optionally, the step of adjusting the supply voltage and / or supply frequency of the high-voltage pulse power supply based on the reinforcement learning model and the air state includes: Determining the scale of the flow separation zone according to the air state transmitted by the first wall hot-wire module and the second wall hot-wire module; Determining whether the difference between the scale of the flow separation zone in the current cycle and the scale of the flow separation zone in the previous cycle is positive. If so, increasing the reward of the reinforcement learning model; Based on the reinforcement learning model, combined with the adjusted reward and the air state, generate the supply voltage and / or supply frequency of the high-voltage pulse power supply for the next cycle.

[0017] Compared with the prior art, the present application has the following beneficial effects: The present application provides an intelligent plasma flow control device and method for incident shock wave boundary layer interference. The device includes a controller, a high-voltage pulse power supply, a flat plate, a plasma synthetic jet actuator, a first wall hot-wire module, a second wall hot-wire module, a shock wave generator, a truss, and a bracket. The bracket is connected to the flat plate. The plasma synthetic jet actuator, the first wall hot-wire module, and the second wall hot-wire module are sequentially and spacedly installed on the flat plate along the upstream to downstream direction. The truss is vertically installed on the bracket. The shock wave generator is connected to the bracket. The upstream end of the shock wave generator is provided with a first inclination structure, and the shock wave generator is located above the first wall hot-wire module and the second wall hot-wire module. The plasma synthetic jet actuator is electrically connected to the high-voltage pulse power supply. The controller is electrically connected to the high-voltage pulse power supply, the first wall hot-wire module, and the second wall hot-wire module respectively. Wherein, when in a supersonic flight environment, the air flow flows from upstream to downstream. The shock wave generator is used to generate an incident oblique shock wave and strike the area between the first wall hot-wire module and the second wall hot-wire module. The plasma synthetic jet actuator is used to form a jet cycle to suppress shock wave boundary layer interference. The first wall hot-wire module and the second wall hot-wire module are used to obtain the air state at the corresponding positions. The controller is used to adjust the supply voltage and / or supply frequency of the high-voltage pulse power supply according to the air state, so as to adjust the discharge voltage and / or discharge frequency of the plasma synthetic jet actuator.

[0018] The intelligent plasma flow control device for novel incident shock wave boundary layer interference provided by the present application can measure the air state through the first wall hot-wire module and the second wall hot-wire module. At the same time, the controller can adjust the discharge voltage and / or discharge frequency of the plasma synthetic jet actuator in real time according to the air state, so that when the flight state changes, the excitation voltage and frequency can be adaptively adjusted, improving the robustness of the entire device.

[0019] To make the above objects, features, and advantages of the present application more obvious and understandable, the following specific preferred embodiments are given below in conjunction with the accompanying drawings and are described in detail as follows. Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0021] Figure 1 Schematic structural diagram of the intelligent plasma flow control device for incident shock wave boundary layer interference provided by this application.

[0022] Figure 2 Bottom view of the intelligent plasma flow control device for incident shock wave boundary layer interference provided by this application.

[0023] Figure 3 Top view of the intelligent plasma flow control device for incident shock wave boundary layer interference provided by this application after removing the flat plate.

[0024] Figure 4 Schematic module diagram of the intelligent plasma flow control device for incident shock wave boundary layer interference provided by this application.

[0025] Figure 5 Schematic structural diagram of the plasma synthetic jet actuator provided by this application.

[0026] Figure 6 For Figure 5 Schematic cross-sectional view corresponding to the structure along lines AA and BB in

[0027] Figure 7 Schematic structural diagram of the first wall hot wire module provided by this application.

[0028] Figure 8 For Figure 7 Schematic cross-sectional view corresponding to the structure along line AA in

[0029] Figure 9 For Figure 7 Schematic cross-sectional view corresponding to the structure along line BB in

[0030] Figure 10 Exemplary flowchart of the intelligent plasma flow control method for incident shock wave boundary layer interference provided by this application.

[0031] Figure 11 Schematic diagram of the processing logic of the intelligent plasma flow control method for incident shock wave boundary layer interference provided by this application.

[0032] In the figure: 100 - Flat plate; 110 - Second inclination structure; 120 - Plasma synthetic jet hole; 200 - Plasma synthetic jet actuator; 201 - Anode; 202 - Cathode; 203 - Isolation boss; 204 - Jet cavity; 205 - Potting cavity; 310 - First wall hot - wire module; 320 - Second wall hot - wire module; 301 - Hot - wire probe; 302 - Set screw; 303 - Fastening screw; 304 - Substrate; 400 - Shock wave generator; 410 - First inclination structure; 420 - Mounting groove; 430 - Third inclination structure; 510 - Left truss; 520 - Right truss; 600 - Bracket; 610 - Base plate; 620 - Cylindrical tail strut; 630 - Set - screw hole; 640 - Connection structure; 700 - Controller; 800 - High - voltage pulse power supply. Detailed implementation manners

[0033] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Components of the embodiments of the present application described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but merely represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts fall within the scope of protection of the present application.

[0035] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of the present application, terms such as "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0036] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0037] As described in the background art, current plasma aerodynamic excitation generally adopts open - loop control, and the optimal excitation voltage and frequency cannot be adaptively adjusted. Therefore, there is a problem of poor robustness.

[0038] In view of this, the present application provides an intelligent plasma flow control device for incident shock boundary layer interference, which adaptively adjusts the discharge voltage and / or discharge frequency of the plasma synthetic jet actuator 200 through a novel structure and a controller, so as to achieve the purpose of improving the robustness of the entire device.

[0039] The following is an exemplary description of the intelligent plasma flow control device for incident shock boundary layer interference provided by the present application: As an optional implementation, please refer to Figures 1 - 4 , the device includes a controller 700, a high-voltage pulse power supply 800, a flat plate 100, a plasma synthetic jet actuator 200, a first wall hot-wire module 310, a second wall hot-wire module 320, a shock generator 400, a truss, and a bracket 600. The bracket 600 is connected to the flat plate 100. The plasma synthetic jet actuator 200, the first wall hot-wire module 310, and the second wall hot-wire module 320 are sequentially and spacedly installed on the flat plate 100 along the upstream to downstream direction. The truss is vertically installed on the bracket 600. The shock generator 400 is connected to the bracket 600. A first inclination structure 410 is provided at the upstream end of the shock generator 400, and the shock generator 400 is located above the first wall hot-wire module 310 and the second wall hot-wire module 320; the plasma synthetic jet actuator 200 is electrically connected to the high-voltage pulse power supply 800, and the controller 700 is electrically connected to the high-voltage pulse power supply 800, the first wall hot-wire module 310, and the second wall hot-wire module 320 respectively. Among them, when in a supersonic flight environment, the air flow flows from upstream to downstream. The shock generator 400 is used to generate an incident oblique shock wave and hit the area between the first wall hot-wire module 310 and the second wall hot-wire module 320; the plasma synthetic jet actuator 200 is used to form a jet cycle to suppress shock boundary layer interference; the first wall hot-wire module 310 and the second wall hot-wire module 320 are used to obtain the air state at the corresponding positions; the controller 700 is used to adjust the supply voltage and / or supply frequency of the high-voltage pulse power supply 800 according to the air state, so as to adjust the discharge voltage and / or discharge frequency of the plasma synthetic jet actuator 200.

[0040] Through the intelligent plasma flow control device for incident shock boundary layer interference provided by the present application, the controller 700 can flexibly adjust the discharge voltage and / or discharge frequency of the plasma synthetic jet actuator 200 according to the air state obtained by the first wall hot-wire module 310 and the second wall hot-wire module 320 until the incident shock boundary layer interference is completely suppressed. That is, the controller 700 can achieve closed-loop control, improving the robustness of the entire device.

[0041] Among them, the upstream and downstream in the present application are directions defined with respect to the air flow direction. When in a flight state, the air flow flows from upstream to downstream. For exampleFigure 1 As shown in the middle view, the left side of the figure is the upstream and the right side is the downstream.

[0042] Moreover, the flat plate 100 described in this application is mainly used for installing the structures of the plasma synthetic jet actuator 200, the first wall hot wire module 310, and the second wall hot wire module 320. Since the plasma synthetic jet actuator 200 is driven by high-voltage pulses during the working state, in order to prevent creepage phenomenon with the actuator under high-voltage conditions, the material of the flat plate 100 is preferably selected as the high-strength non-metallic material Peek (polyether ether ketone).

[0043] Meanwhile, in order to reduce the wind resistance of the entire device, a second inclination structure 110 is provided at the upstream end of the flat plate 100. The inclination structure described in this application means that both the surface and the bottom surface of the flat plate 100 are flat planes, and the length of the bottom surface of the flat plate 100 is less than the length of the surface of the flat plate 100, so that the side surface of the upstream end of the flat plate 100 is an inclined surface, the angle between this inclined surface and the surface of the flat plate 100 is an acute angle, and the angle between it and the bottom surface of the flat plate 100 is an obtuse angle, thereby making the entire upstream end form a downward-tilted wedge structure (inclination structure). In order to enhance the effect of reducing wind resistance, the inclination angle of the upstream end of the flat plate 100 is set to 10° - 20°.

[0044] Furthermore, the bottom of the flat plate 100 is connected to the bracket 600, and the bracket 600 mainly plays a supporting role. In order to further reduce the wind resistance, the bottom of the flat plate 100 is set as a stepped structure, that is, the upstream end of the flat plate 100 is lower than the remaining positions of the bottom surface of the flat plate 100, forming a height difference. The position thickness at the connection between the bracket 600 and the flat plate 100 is equal to this height difference, so that after the bottom of the flat plate 100 is fixed to the bracket 600, the bottom surface of the bracket 600 is flush with the bottom surface of the upstream end of the flat plate 100. Therefore, the connection between the flat plate 100 and the bracket 600 is located on the bottom surface of the flat plate 100, and their bottom surfaces are flush with each other, which can effectively avoid the generation of clutter on the surface and affect the flow field.

[0045] To ensure the firmness of the fixation between the flat plate 100 and the bracket 600, as Figure 2 shown, the flat plate 100 is connected to the bracket 600 through the connection structure 640 at the bottom. In this application, the connection structure 640 includes 8 screws in 4 groups. Among them, since the plasma synthetic jet actuator 200, the first wall hot wire module 310, and the second wall hot wire module 320 are installed at the middle position of the bottom surface of the flat plate 100, 8 screws can respectively fix both sides of the flat plate 100. 4 screws are fixed on each side to achieve a stable connection between the flat plate 100 and the bracket 600.

[0046] To facilitate the installation of the plasma synthetic jet actuator 200, the first wall hot-wire module 310, and the second wall hot-wire module 320, corresponding installation slots are reserved on the flat plate 100. Of course, in order to match the installation slots, a hollow structure is also adopted at the corresponding positions of the bracket 600.

[0047] Among them, in the middle of the surface of the flat plate 100, at the position corresponding to the plasma synthetic jet actuator 200, a row of plasma synthetic jet holes 120 are reserved. The aperture range can be selected from 1 to 3 mm. Considering from the perspective of increasing the mass flow rate of the jet, the preferred aperture is 3 mm. The spanwise (i.e., the width direction of the flat plate 100) spacing between two adjacent jet holes should be 5 to 10 times the jet aperture. The number of plasma synthetic jet holes 120 is determined by the spanwise dimension of the flat plate 100 and the spanwise spacing of the jet holes. As Figure 3 described, the spanwise dimension of the flat plate 100 provided in the present application is 100 mm, and the corresponding number of plasma synthetic jet holes 120 is 5. At the same time, downstream of the jet holes, 2 groups of installation slots are reserved for installing the first wall hot-wire module 310 and the second wall hot-wire module 320, and the first wall hot-wire module 310, the second wall hot-wire module 320, and the flat plate 100 are firmly fitted through screws.

[0048] As an implementation method, please refer to Figures 5 - 6 , Figure 6 where a is Figure 5 the schematic cross-sectional view corresponding to the structure along line AA in Figure 6 and b is Figure 5 the schematic cross-sectional view corresponding to the structure along line BB in

[0049] The plasma synthetic jet actuator 200 is integrally arranged as a T-shaped long strip structure and can be embedded in the reserved slot of the flat plate 100 to form a flat bottom surface after being tightly fitted with the flat plate 100. The main function of the plasma synthetic jet actuator 200 is to generate a synthetic jet through high-voltage plasma discharge to suppress the shock wave boundary layer interference. Since high temperature will be generated during the plasma discharge process, the exciter material is preferably a non-metallic high-temperature resistant ceramic material, such as alumina, zirconia, etc. Figure 5As shown in the figure, in the plasma synthetic jet actuator 200 provided by the present application, 5 pairs of positive and negative high-voltage electrodes are evenly distributed along the span direction in the jet cavity 204. Of course, the number of electrode pairs can be adjusted according to the actual size of the jet cavity 204. Moreover, the electrode materials of the anode 201 and the cathode 202 are tungsten needles with high temperature resistance, and the diameter is 1 mm. At the same time, the distance between adjacent two electrode pairs is also determined by the transverse width of the jet cavity 204. In order to ensure that the breakdown voltage is between 10 kV and 20 kV, the distance between adjacent two electrode pairs is set to 3 - 5 mm, for example, it can be set to 4 mm.

[0050] Among them, the isolation boss 203 is used to prevent the ablation of the cavity material. Specifically, during the operation of the actuator, the anode 201 and the cathode 202 are respectively connected to the high-voltage pulse power supply 800 through high-voltage-resistant wires. Ideally, a discharge arc will be formed at the tips of the anode 201 and the cathode 202 to heat the gas inside the jet cavity 204. However, during the actual operation process, surface discharge will be formed at the roots of the anode 201 and the cathode 202 on the bottom surface of the cavity, causing the ablation of the cavity material. Therefore, in order to avoid this situation, an isolation boss 203 is provided inside the actuator provided by the present application, which increases the total length of the surface discharge path along the bottom surface, thereby effectively avoiding the ablation of the cavity material. Optionally, the width of the isolation boss 203 is 1 mm and the height is 2 mm.

[0051] In addition, in order to realize the fixation of the electrodes and high-voltage insulation, a rectangular potting cavity 205 is also provided at the bottom of the main body. After the tungsten needle electrodes and the metal wires are connected, epoxy potting adhesive is injected into the potting cavity 205 to realize the sealing of the potting cavity 205.

[0052] In the present application, the basic working principle of the plasma synthetic jet actuator 200 to generate a jet is as follows: Pulse high voltage (in the range of 5 kV - 30 kV) is applied to the electrodes of the actuator, and the gas between the electrodes is broken down to form high-temperature plasma; an instantaneous high voltage is generated inside the jet cavity 204, forcing the high-temperature and high-pressure gas mass to be ejected from the plasma synthetic jet hole 120 at a high speed; when the jet is ejected, due to the pressure difference inside and outside the cavity, the external gas backfills and supplements through the jet hole, so a periodic synthetic jet cycle of "jet - suction - jet - suction" is formed. On the one hand, this synthetic jet can inject momentum in the shock wave boundary layer interference region, enhancing the kinetic energy of the boundary layer fluid to resist the adverse pressure gradient; on the other hand, it perturbs the local high-speed flow field structure through the periodic jet, forming streamwise vortex structures in the shock wave-induced separation region, effectively suppressing the formation of turbulent separation bubbles, and enhancing the suppression effect on the shock wave boundary layer interference.

[0053] For the first wall hot-wire module 310 and the second wall hot-wire module 320 provided in this application, their structures are exactly the same. The structure of the first wall hot-wire module 310 is used for exemplary illustration in this application. Please refer to Figures 7 - 9 , the first wall hot-wire module 310 includes a hot-wire probe 301, a setscrew 302, a fastening screw 303 and a base 304. The base 304 is arranged in an inverted T-shaped structure. There is a mounting hole at the top of the base 304. The hot-wire probe 301 is installed in the mounting hole and fixed by the setscrew 302. Mounting holes are provided on both sides of the base 304. The fastening screws 303 are located in the mounting holes on both sides and fix the base 304 to the flat plate 100.

[0054] Among them, the base 304 is made of a high-temperature resistant and high-strength non-metallic material, such as Peek material or polyimide material. Moreover, in the first wall hot-wire module 310 provided in this application, the number of hot-wire probes 301 is three, and they are used to measure the air velocity attached to the wall, and then measure the friction drag distribution along the spanwise direction of the boundary layer of the flat plate 100. And the hot-wire probe 301 is set in a cylindrical shape with a diameter of 3 mm - 5 mm.

[0055] In this application, an assembly tolerance of ±0.05 mm is reserved between the hot-wire probe 301 and the base 304, and setscrew holes are provided on the front and back of the base 304. After the hot-wire probe 301 is installed in the mounting hole at the top of the base 304, the distance between the hot-wire probe 301 and the wall of the base is only 0.2 mm, and it is fixed by the setscrew 302. After the first wall hot-wire module 310 is installed on the flat plate 100, the first wall hot-wire module 310 can be fixed through the cooperation of the mounting holes provided on both sides of the base 304 and the fastening screws 303.

[0056] It should be noted that although the structures of the first wall hot-wire module 310 and the second wall hot-wire module 320 are exactly the same, and both are used to measure the air state (i.e., air velocity), their installation positions and the purposes of measuring the air state are not the same.

[0057] Specifically, the first wall hot-wire module 310 is installed in the middle of the flat plate 100, upstream of the shock boundary layer interference region (the shock boundary layer interference region is located between the first wall hot-wire module 310 and the second wall hot-wire module 320). Its function is to detect and determine whether flow separation occurs at its set position, providing a status input for the subsequent intelligent control of the controller 700. The second wall hot-wire module 320 is installed downstream of the flat plate 100, corresponding to the downstream of the shock boundary layer interference region. Its function is to evaluate whether the plasma synthetic jet has completely eliminated the flow separation in the downstream boundary layer. After the first wall hot-wire module 310 and the second wall hot-wire module 320 are combined, it is possible to evaluate the scale of the flow separation induced by the shock boundary layer interference and the control efficiency of the plasma actuator.

[0058] It should also be noted that after installation, the plasma synthetic jet actuator 200, the first wall hot-wire module 310, and the second wall hot-wire module 320 are all installed at the bottom of the flat plate 100, and the surfaces of the plasma synthetic jet actuator 200, the first wall hot-wire module 310, and the second wall hot-wire module 320 are flush with the surface of the bracket 600 to avoid generating clutter and affecting the flow field. For example, please refer again to Figure 2 and Figure 3 , Figure 2 In, after the plasma synthetic jet actuator 200, the first wall hot-wire module 310, and the second wall hot-wire module 320 are installed, they are embedded in the structure of the flat plate 100 and the bracket 600, and the surface is flush with the bottom surface of the bracket 600. Figure 3 In, only the jet holes, the top surface of the base body 304 of the first wall hot-wire module 310 and the second wall hot-wire module 320 are exposed on the surface of the flat plate 100, and the mounting holes provided on the top surface of the base body 304 are exposed, that is, the hot-wire probe 301 is exposed. At the same time, the exposed top surface of the base body 304 is flush with the surface of the flat plate 100, thereby avoiding generating clutter as a whole.

[0059] The bracket 600 provided in this application includes a bottom plate 610 and a cylindrical tail strut 620, both of which are made of high-strength metal materials to support the entire device. Among them, the bottom plate 610 is connected to the flat plate 100 by 4 groups of a total of 8 screws, and the middle part is hollowed out to facilitate the assembly of the actuator, the wall hot-wire module and the flat plate 100. At the same time, an installation part for fixing the truss is provided at the downstream end of the bottom plate 610, and a height difference is formed between the installation part and the rest of the bottom plate 610, and this height difference is equal to the thickness of the flat plate 100, so that after the bracket 600 and the flat plate 100 are assembled, the installation part is flush with the surface of the flat plate 100.

[0060] The cylindrical tail strut 620 provides an external interface and a fixed end for the entire device. The circuit traces of the plasma synthetic jet actuator 200, the first wall hot-wire module 310, and the second wall hot-wire module 320 can be led out through the hollow area of the cylindrical tail strut 620. At the same time, when the device is placed in the wind tunnel measurement system for testing, the cylindrical tail strut 620 can be used for fixation, thereby preventing the entire device from shaking. Among them, the diameter of the cylindrical tail strut 620 is 20 mm, and a set screw hole 630 is provided on the cylindrical tail strut 620. When using the cylindrical tail strut 620 for fixation, the cylindrical tail strut 620 and the outside can be fixed by 2 groups of 4 set screws.

[0061] The truss is mainly used to support the shock wave generator 400, and high-strength metal materials such as stainless steel can be selected. In this application, the truss includes a left truss 510 and a right truss 520, and the structures of the left truss 510 and the right truss 520 are exactly the same. Their height is 30 mm, and the upper and lower surfaces are respectively fixed to the shock wave generator 400 and the bracket 600 by 4 fastening screws, playing a vertical support role. Among them, the upstream end and the downstream end of the left truss 510 and the right truss 520 are set in a wedge shape, so as to achieve the purpose of reducing wind resistance.

[0062] In this application, a first inclination structure 410 is provided at the upstream end of the shock wave generator 400. As an implementation, the angle of the first inclination structure 410 is 5° - 20°, for example, it can be set to 10 degrees, so as to generate an incident shock wave, and the incident shock wave hits the area between the first wall hot-wire module 310 and the second wall hot-wire module 320. The shock wave generator 400 can also be made of high-strength metal materials such as stainless steel.

[0063] Moreover, a long strip-shaped installation groove 420 is provided on the side of the shock wave generator 400. The length of the installation groove 420 is set to 50 - 100 mm, and the length of the installation groove 420 is greater than the length of the truss, so that the truss can be installed at any position of the installation groove 420 and fixed by a fixing member. By providing the installation groove 420 on the side of the shock wave generator 400, on the one hand, it is convenient to connect with the truss through countersunk head fastening screws. On the other hand, it is convenient for the shock wave generator 400 to move back and forth along the direction of the flat plate 100. That is, during the test, the position of the shock wave generator 400 can be manually adjusted, thereby adjusting the position of the incident shock wave, which is convenient for simulating different working conditions during flight.

[0064] At the same time, a third inclination structure 430 is provided at the downstream end of the shock wave generator 400, and the inclination angle of the upstream end of the flat plate 100 is the same as that of the downstream end of the shock wave generator 400, generally set to 10° - 20°, so as to effectively reduce wind resistance as a whole.

[0065] It can be understood that through the intelligent plasma flow control device for incident shock wave boundary layer interference provided by the present application, an effective flow field environment of shock wave boundary layer interference can be created in the wind tunnel measurement system. And in this environment, the power supply voltage and / or power supply frequency of the high-voltage pulse power supply 800 can be adjusted by the controller 700, and finally, the complete suppression of shock wave boundary layer interference can be achieved. At the same time, when creating the flow field environment of shock wave boundary layer interference, the degree of the first inclination structure 410 at the upstream end of the shock wave generator 400 can be adjusted, and the installation position between the shock wave generator 400 and the truss can be adjusted, so as to simulate different working conditions during normal flight and improve the flexibility of simulation.

[0066] After the device is installed in the supersonic wind tunnel, when the wind tunnel is started, when the supersonic airflow flows over the surface of the flat plate 100, a boundary layer with a relatively low velocity will be formed under the action of viscosity; at the same time, the supersonic airflow is compressed by the wedge of the shock wave generator 400 (i.e., the first inclination structure 410 at the upstream end), generating an incident oblique shock wave with a deflection angle, which hits the area between the first wall hot-wire module 310 and the second wall hot-wire module 320 (i.e., the experimental observation area); under the strong adverse pressure gradient of the shock wave, the kinetic energy in the boundary layer is rapidly dissipated and flow separation occurs, forming characteristics such as an unsteady separation bubble, creating an effective shock wave boundary layer interference.

[0067] Moreover, after creating the flow field environment, through the plasma synthetic jet actuator 200, the first wall hot-wire module 310, and the second wall hot-wire module 320 of the device, the controller 700 can achieve closed-loop control, adjust the power supply voltage and / or power supply frequency of the high-voltage pulse power supply 800, and then adjust the discharge voltage and / or discharge frequency of the plasma synthetic jet actuator 200 to completely suppress the shock wave boundary layer interference. In the closed-loop control of the controller 700, the closed-loop control can be achieved by combining machine learning methods, which is not limited herein.

[0068] Based on the above implementation manner, the embodiment of the present application further provides an intelligent plasma flow control method for incident shock wave boundary layer interference. This method is applied to the controller in the above device. Please refer to Figure 10 , and the method includes: S102, controlling the power supply voltage and / or power supply frequency of the high-voltage pulse power supply to make the plasma synthetic jet actuator work.

[0069] S104, obtaining the air state transmitted by the first wall hot-wire module and the second wall hot-wire module.

[0070] S106, adjusting the power supply voltage and / or power supply frequency of the high-voltage pulse power supply based on the reinforcement learning model and the air state until the shock wave boundary layer interference is completely suppressed.

[0071] Among them, the steps of S106 include: S1061, determining the scale of the flow separation zone according to the air state transmitted by the first wall hot-wire module and the second wall hot-wire module.

[0072] S1062, determining whether the difference between the scale of the flow separation zone in the current cycle and that in the previous cycle is positive. If so, increasing the reward of the reinforcement learning model.

[0073] S1063, generating the supply voltage and / or supply frequency of the high-voltage pulse power supply for the next cycle based on the reinforcement learning model, combined with the adjusted reward and air state.

[0074] Please combine Figure 11 , after creating the shock wave flow field environment, sensing is performed through the first wall hot-wire module 310 and the second wall hot-wire module 320 located upstream and downstream to achieve state monitoring and generate the flow field state s. The corresponding flow field state s includes two parts: the boundary layer separation point measured by the first wall hot-wire module 310 and the boundary layer attachment point measured by the second wall hot-wire module 320 (both the first wall hot-wire module 310 and the second wall hot-wire module 320 are used to measure the air velocity, but the meanings represented by their measurement results are different). Among them, the action a is the supply voltage and discharge frequency of the plasma synthetic jet actuator 200, which can be adjusted by a high-voltage pulse power supply; the reward r is defined in the form of a difference, specifically, the scale of the flow separation zone in the current control cycle (the area affected by the shock wave boundary layer between the first wall hot-wire module 310 and the second wall hot-wire module 320) minus the scale of the flow separation zone in the previous control cycle; if the difference is positive, it indicates that the separation zone becomes smaller after applying flow control in a certain state, so more rewards should be given. The control law of active flow control is the function mapping relationship from the state s to the action a, which can be optimized through a reinforcement learning framework. For example, it can be implemented through a neural network framework.

[0075] The specific process of using reinforcement learning to optimize the control law is as follows: randomly initialize the control law; then, monitor the current state s and output control instructions (i.e., action a) according to the preset control law; again, evaluate the control reward r, store the experience samples (including the action a taken for the state s and the obtained reward r before) in the experience library, shuffle the order of the experience samples to make them independent of each other for the subsequent normal update of the network; after reaching the specified number of steps, update the execution network relying on PPO, actor-critic or other learning frameworks. At the same time, to enable the network to be stably trained, a target network with an update delay of a certain number of steps relative to the execution network is introduced, and the delay steps are between 2 and 32. Of course, the parameters can also be updated by using the gradient descent method through a loss function (such as the mean square error function, etc.); at the same time, randomly input the experience samples from the experience library into the network. Finally, after multiple iterations, change the instantaneous input frequency of the actuator to control the change of the actuator jet, and more rewards can be obtained, achieving the best shock separation suppression effect with the least amount.

[0076] In summary, through the structural design with an adjustable incident shock position along the flow direction, this application solves the limitations of the traditional fixed-position shock impact, and flexibly adapts to the actual separation regions of different wind tunnel test models; uses two wall hot-wire modules to obtain the flow field state in real time, and combines the reinforcement learning algorithm to autonomously optimize the excitation voltage and / or frequency of the plasma synthetic jet actuator 200 to achieve the best shock separation suppression effect, solving the problems of low efficiency of traditional manual parameter adjustment, high cost of wind tunnel tests, and difficulty in quantifying the control effect.

[0077] At the same time, the intelligent plasma flow control device for the incident shock boundary layer interference provided by this application has at least the following advantages: 1. This application can provide stronger plasma excitation: In the traditional incident shock model based on the synthetic jet actuator, most use single-point or double-point jet layouts, and the jet intensity and action range are limited by the local flow field characteristics. This application uses five jet ports arranged equidistantly along the spanwise direction to actively control the incident shock separation region, improving the control effect of the shock separation region.

[0078] 2. More flexible control position adjustment: The shock position in the traditional incident shock wind tunnel test model is relatively fixed, and it is difficult to accurately match the actual separation regions of different wind tunnel test conditions. The present invention realizes a dual design of angle replacement on demand and flexible adjustment of the position along the flow direction in the structure of the incident shock generator, realizing the dynamic matching of the incident shock intensity and the model test region, and improving the compatibility of the model under different wind tunnel test conditions.

[0079] 3. High optimization efficiency: Traditional active flow control methods for incident shock waves have defects such as low efficiency of manual parameter adjustment, high cost of wind tunnel tests, and great difficulty in quantifying control effects. In this application, the first wall hot-wire module and the second wall hot-wire module are used to obtain flow field information in real time, and the excitation voltage and / or frequency of the plasma synthetic jet actuator are autonomously optimized in combination with the reinforcement learning algorithm to achieve the best shock separation suppression effect. This method greatly reduces the manual and test costs, and evaluates the control effect through hot-wire data, which has important value for promoting the development of intelligent high-speed flow control.

[0080] 4. Strong adaptability: In this application, the plasma synthetic jet actuator works in a closed-loop state. When the flight conditions change, the flow field information measured by the first wall hot-wire module and the second wall hot-wire module will change, which will also cause an adaptive adjustment of the actuator control command. Compared with the original open-loop fixed-parameter control, it has the advantages of stronger adaptability and better robustness.

[0081] The above are only the preferred embodiments of this application and are not used to limit this application. For those skilled in the art, this application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the protection scope of this application.

[0082] For those skilled in the art, it is obvious that this application is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of this application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of this application is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in this application. Any reference signs in the claims should not be regarded as limiting the claims involved.

Claims

1. An intelligent plasma flow control device for incident shock wave boundary layer interference, characterized in that The device includes a controller, a high-voltage pulse power supply, a flat plate, a plasma synthetic jet actuator, a first wall hot-wire module, a second wall hot-wire module, a shock generator, a truss, and a bracket. The bracket is connected to the flat plate. The plasma synthetic jet actuator, the first wall hot-wire module, and the second wall hot-wire module are sequentially and spacedly installed on the flat plate in the upstream to downstream direction. The truss is vertically installed on the bracket. The shock generator is connected to the bracket. A first inclination structure is provided at the upstream end of the shock generator, and the shock generator is located above the first wall hot-wire module and the second wall hot-wire module. The plasma synthetic jet actuator is electrically connected to the high-voltage pulse power supply. The controller is electrically connected to the high-voltage pulse power supply, the first wall hot-wire module, and the second wall hot-wire module respectively. Among them, When in a supersonic flight environment, the air flow flows from upstream to downstream. The shock generator is used to generate an incident oblique shock wave and strike the area between the first wall hot-wire module and the second wall hot-wire module. The plasma synthetic jet actuator is used to form a jet cycle to suppress the shock wave boundary layer interference. The first wall hot-wire module and the second wall hot-wire module are used to obtain the air state at the corresponding positions. The controller is used to adjust the supply voltage and / or supply frequency of the high-voltage pulse power supply according to the air state, so as to adjust the discharge voltage and / or discharge frequency of the plasma synthetic jet actuator.

2. The intelligent plasma flow control device for incident shock wave boundary layer interference according to claim 1, wherein A second inclination structure is provided at the upstream end of the flat plate. A third inclination structure is provided at the downstream end of the shock generator. And the inclination angles of the second inclination structure and the third inclination structure are the same.

3. The intelligent plasma flow control device for incident shock wave boundary layer interference according to claim 1, characterized in that The inclination angle of the first inclination structure is 5° to 20°.

4. The intelligent plasma flow control device for incident shock wave boundary layer interference according to claim 1, wherein A long strip-shaped installation groove is provided on the side of the shock generator. The length of the installation groove is greater than the length of the truss. The truss is installed at any position of the installation groove and fixed by a fixing member.

5. The intelligent plasma flow control device for incident shock wave boundary layer interference according to claim 1, characterized in that The plasma synthetic jet actuator includes a cathode, an anode, an isolation boss, and a main body. The main body is provided with a jet cavity. Each cathode and an anode form an electrode pair and are arranged in the jet cavity. And the isolation boss is located between the cathode and the anode of each electrode pair. The cathode and the anode of each electrode pair are both connected to the high-voltage pulse power supply.

6. The intelligent plasma flow control device for incident shock wave boundary layer interference according to claim 5, wherein, The distance between adjacent two electrode pairs is set to 3 to 5 mm.

7. The intelligent plasma flow control device for incident shock wave boundary layer interference according to claim 1, characterized in that, The structures of the first wall hot-wire module and the second wall hot-wire module are the same. And the first wall hot-wire module includes a hot-wire probe, a setscrew, a fastening screw, and a base. The base is of an inverted T-shaped structure. An installation hole is provided at the top of the base. The hot-wire probe is installed in the installation hole and fixed by the setscrew. Installation holes are also provided on both sides of the base. The fastening screws are located in the installation holes on both sides and fix the base to the flat plate.

8. The intelligent plasma flow control device for incident shock wave boundary layer interference according to claim 1, characterized in that, The plasma synthetic jet actuator, the first wall hot-wire module, and the second wall hot-wire module are all installed at the bottom of the flat plate, and the surfaces of the plasma synthetic jet actuator, the first wall hot-wire module, and the second wall hot-wire module are flush with the surface of the bracket.

9. An intelligent plasma flow control method for incident shock wave boundary layer interference, characterized in that, Applied to the intelligent plasma flow control device for the incident shock wave boundary layer interference as described in any one of claims 1 to 8, the method includes: Controlling the supply voltage and / or supply frequency of the high-voltage pulse power supply to make the plasma synthetic jet actuator work; Obtaining the air state transmitted by the first wall hot-wire module and the second wall hot-wire module; Adjusting the supply voltage and / or supply frequency of the high-voltage pulse power supply based on the reinforcement learning model and the air state until the shock wave boundary layer interference is completely suppressed.

10. The intelligent plasma flow control method for incident shock wave boundary layer interference according to claim 9, characterized in that The step of adjusting the supply voltage and / or supply frequency of the high-voltage pulse power supply based on the reinforcement learning model and the air state includes: Determining the scale of the flow separation zone according to the air state transmitted by the first wall hot-wire module and the second wall hot-wire module; Determining whether the difference between the scale of the flow separation zone in the current cycle and the scale of the flow separation zone in the previous cycle is positive. If so, increasing the reward of the reinforcement learning model; Generating the supply voltage and / or supply frequency of the high-voltage pulse power supply for the next cycle based on the reinforcement learning model combined with the adjusted reward and the air state.

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