Array plasma synthetic jet device with nanosecond pulse dielectric barrier discharge boosting

Abstract

A nanosecond pulse dielectric barrier discharge boosted array plasma synthetic jet actuator comprises, from top to bottom: a top cover 10, a high voltage electrode plate 20, an insulating dielectric plate 30 and a grounded metal plate 40. A working method of an array plasma synthetic jet device based on the nanosecond pulse dielectric barrier discharge boosted array plasma synthetic jet of the actuator is also provided. In one jet cycle, the complete working process includes three stages: an impact boosting stage, an array jet stage and a multi-hole suction recovery stage. The array actuator of the present invention does not require a complex load matching circuit design or a power supply optimization design, and has the advantages of simple wiring, low implementation cost, easy large-scale expansion, high operating frequency, and good pulse repeatability.

Description

Technical Field

[0001] The invention relates to the field of active flow control, in particular to an array plasma synthetic jet actuator using nanosecond pulse dielectric barrier discharge shock supercharging. Background Art

[0002] In 2010, the American Institute of Aeronautics and Astronautics listed active flow control technology as one of the top ten key technologies supporting the future development of the global aviation field. The core of this technology is the actuator, which can induce controllable disturbances to change the external flow field of the aircraft and improve the performance of the aircraft and engine. The plasma synthetic jet actuator is a high-intensity actuator with zero mass flow. Its basic working principle is to quickly heat and pressurize the gas gap inside the semi-enclosed cavity through a pulse arc, inducing the jet to periodically eject from the small hole. The maximum jet velocity of the actuator can reach 500m / s, and the maximum operating frequency exceeds 10kHz. Therefore, it is particularly suitable for flow control under high speed and high Reynolds number. However, due to the limited gas area that can be heated by a single arc, the cavity size of the plasma synthetic jet actuator is generally between 5-15mm. The corresponding jet aperture is generally set at 1-3mm, and the range of flow field that can be controlled is extremely limited. In order to apply active flow control technology on large civil airliners and fighter jets, dozens or even hundreds of plasma synthetic jet actuators must be expanded into an array to achieve flow field control capabilities of the order of 0 (1-10m). Due to the negative impedance characteristics of arc discharge, directly connecting multiple plasma synthetic jet actuators in parallel cannot achieve simultaneous operation of the actuators within the array. At present, there are two types of solutions to achieve array plasma synthetic jets. The first is to optimize the power supply design and divide the high-voltage output end of the plasma synthetic jet power supply into several relatively independent loops; each loop has an energy storage device, which can output a pulse high voltage to power the exciter, and finally realize the "synchronous operation" of each exciter inside the array; the typical representatives of this type of solution are "CN105119517A, Shao Tao, Wang Lei, Zhang Cheng, Yan Ping, Luo Zhenbing, Wang Lin; High-voltage pulse power supply for synchronous discharge of multiple plasma synthetic jet exciters", "CN104682765A, Shao Tao, Wang Lei, Zhang Cheng, Yan Ping, Luo Zhenbing, Wang Lin; Device and method for synchronous discharge of multiple plasma synthetic jet exciters". The second is to carry out load matching design, connecting components such as resistors and capacitors in series and parallel with the gas discharge gap to ensure that the voltage in the discharge circuit will not drop significantly before and after breakdown; finally, the high-voltage pulse can be transmitted sequentially to achieve "sequential breakdown" of each plasma synthetic jet actuator inside the array; typical representatives of this type of solution are "CN110933832A, Wu Yun, Zhang Zhibo, Jin Di, Gan Tian, ​​Song Huimin, Jia Min, Liang Hua; Single power supply driven array plasma synthetic jet flow control device and flow control method", "CN106050593, Shao Tao, Han Lei, Luo Zhenbing, Sun Yaohong, Wang Lin, Yan Ping; Plasma synthetic jet series discharge device based on Marx generator".

[0003] However, both of the above two solutions have many problems in aviation applications. In the first solution, for each additional actuator, an additional high-voltage energy storage capacitor and several high-voltage silicon stacks are required. When used to power a large-scale plasma actuator array, the power supply is bulky, expensive, and unacceptably heavy. The load matching components in the second solution are all low-power devices, which are relatively cheap, but the overall wiring is complicated; the circuit operating frequency is determined by the charging rate of the front-end large-capacity energy storage capacitor and the breakdown voltage of the first electrode gap. The pulse frequency cannot be adjusted in real time, and the typical operating frequency is only 10Hz; and the pulse repeatability is poor due to the fluctuation of the electrode gap breakdown voltage (Zhibo Zhang, Yun Wu, Min Jia et al. The multichannel discharge plasma synthetic jet actuator, Sensors and Actuators A: Physical, 2017, 253: 112-117). Therefore, how to produce a high-frequency and high-repeatability plasma synthetic jet array at a low cost is a technical problem that needs to be solved urgently. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention proposes an array plasma synthetic jet actuator with nanosecond pulse dielectric barrier discharge boosting, comprising: a top cover 10, a high voltage electrode plate 20, an insulating dielectric plate 30 and a grounding metal plate 40; wherein

[0005] The top cover 10 is a rectangular body made of insulating material, and the upper surface is square; the outer contour length and width of the top cover 10 need to be adaptively designed according to the actual application; the top cover 10 is hollowed out to form a rectangular internal cavity, and the lower part is open. When it is matched with the high-voltage electrode plate 20 and the insulating medium plate 30, a semi-enclosed, flat square plasma discharge cavity, that is, the exciter cavity 105, is formed; on the upper surface of the top cover 10, a plurality of convergent jet holes 102 are processed from bottom to top along the direction perpendicular to the wall surface, and the jet holes 102 have a plurality of convergent jet holes 102 on the upper surface. Small at the top and large at the bottom; these jet holes 102 are arranged in an N×M array, serving as the throat for the gas to flow into the exciter cavity 105 from top to bottom and flow out from bottom to top; the throat outlet 101 located on the upper surface of the top cover 10 is circular; the throat inlet 103 located on the upper surface of the exciter cavity 105 is also circular; the central axis of the jet hole is perpendicular to the upper surface of the top cover 10, or forms a certain angle with the normal of the top cover 10; as long as the lower inlet area of ​​the jet hole 102 is greater than the upper outlet area, and the cross-sectional area from bottom to top and from inlet to outlet is monotonically reduced;

[0006] The electrode plate 20 is made of a thin sheet metal plate; the electrode plate has a dense mesh shape; each position of the jet hole array 102 corresponds to a mesh, and the axes of the two coincide; the center spacing of adjacent jet holes is the same as the center spacing of adjacent mesh holes; the outermost mesh holes are kept at a certain distance from the edge of the electrode plate 20; the length and width of the electrode plate 20 are basically the same as the length and width of the exciter cavity 105, so that the electrode plate 20 is conveniently embedded in the top cover 10 from bottom to top;

[0007] The insulating dielectric plate 30 is a thin rectangular body; the projection of the insulating dielectric plate 30 on the horizontal plane coincides with the projection of the top cover 10, that is, the length and width of the two are the same;

[0008] The grounding metal plate 40 is a thin rectangular body; the projection of the grounding metal plate 40 on the horizontal plane coincides with the projection of the top cover 10, that is, the length and width of the insulating dielectric plate 30 and the grounding metal plate 40 are the same as those of the outer shell 10; during installation, the lower surface of the insulating dielectric plate 30 is tightly combined with the upper surface of the grounding metal plate 40; the outer shell 10, the electrode plate 20, the insulating dielectric plate 30 and the grounding metal plate 40 are assembled together in sequence from top to bottom to form an exciter.

[0009] In one embodiment of the present invention,

[0010] The thickness of the top cover 10 is 4-6 mm; the length and width of the outer contour of the top cover 10 are 50 mm-500 mm;

[0011] The diameter of the throat outlet 101 is in the range of 1-2 mm; the diameter of the throat inlet 103 is in the range of 2-4 mm;

[0012] The throat length of the convergent jet hole 102 is 1-3 mm; the row spacing and column spacing of the jet hole array 102 should be set to 3-5 times the throat outlet diameter, ranging from 3-15 mm.

[0013] In a specific embodiment of the present invention,

[0014] The top cover 10 is 4 mm thick and is made of insulating materials such as nylon, polyimide, PEEK or ceramics; the outer contour length and width of the top cover 10 are 50 mm*50 mm;

[0015] The jet hole 102 is in the shape of a truncated cone, and the upper surface of the truncated cone is parallel to the lower surface;

[0016] The diameter of the throat outlet 101 is 1.5 mm; the diameter of the throat inlet 103 is 3 mm;

[0017] The throat length of the convergent jet hole 102 is 2 mm.

[0018] In another embodiment of the present invention,

[0019] The thickness of the electrode plate 20 is 0.01 mm-1 mm (preferably 0.05 mm);

[0020] The maximum diameter of the mesh of the electrode plate 20 is 2-5 mm (preferably 4 mm).

[0021] In another specific embodiment of the present invention,

[0022] The thickness of the electrode plate 20 is 0.05 mm;

[0023] The maximum mesh diameter of the electrode plate 20 is 4 mm;

[0024] The electrode plate 20 is a dense square grid, a triangular grid, a honeycomb grid, or a comb grid.

[0025] In another embodiment of the present invention, the insulating dielectric plate 30 is made of insulating materials such as polyimide, nylon, acrylic, PPEK, ceramic or mica; when thin film polyimide is used, the thickness range is 0.05-0.2 mm; when other materials are used, the thickness range is 0.5-2 mm.

[0026] In yet another embodiment of the present invention, the grounding metal plate 40 has a thickness ranging from 2 to 4 mm.

[0027] In another embodiment of the present invention, the depth of the actuator cavity 105 is 1-4 mm; the thickness of the side wall of the top cover 10 is 4-10 mm.

[0028] A working method of an array plasma synthetic jet device with nanosecond pulse dielectric barrier discharge boost is also provided. The device is based on the above-mentioned array plasma synthetic jet actuator with nanosecond pulse dielectric barrier discharge boost, wherein the high-voltage output end of the high-voltage nanosecond pulse power supply 50 is connected to the electrode plate 20 through a lead 201, and the ground end is connected to the ground metal plate 40 through a lead 401; it is characterized in that within one jet cycle, the complete working process includes three stages: an impact boost stage, an array jet stage and a porous air suction recovery stage;

[0029] step1, in the shock boosting stage, the high-voltage nanosecond pulse power supply 50 outputs a high-voltage pulse and applies it to the electrode plate 20; since there is a tip effect and the electric field strength is concentrated at each edge of the electrode plate 20, a discharge current column is first generated near the edge; under the action of the rising edge of the high-voltage nanosecond pulse, the current column continuously expands outward along the direction of the electric field, forming a dielectric barrier discharge plasma region near the edge of the electrode; in this region, high-energy electrons ionized from some gas molecules continuously bombard other non-ionized gas molecules, generating a large number of excited state particles; these excited state particles release a large amount of heat during the extinguishing process, heating the temperature of the gas in the plasma region to form high-temperature gas within the nanosecond time scale; since the heating time scale is extremely short, the high-temperature gas has no time to expand, so the pressure in the plasma region increases sharply, inducing the generation of a shock wave 106; the shock wave 106 propagates from the plasma region to the surroundings, and through continuous reflection and convergence, the temperature and pressure of the entire exciter cavity 105 are raised to a level far higher than the atmospheric pressure; at this point, the shock boosting stage is completed;

[0030] Step 2: In the array jet stage, driven by the high pressure inside the actuator cavity 105, the high-temperature gas is quickly ejected from the convergent jet hole 102 from the inside to the outside, forming a high-speed jet array 60 for flow control in supersonic or other occasions; during the jet ejection process, the pressure inside the actuator cavity 105 will continue to decrease; when the pressure inside the cavity 105 is less than or equal to the atmospheric pressure, the jet ends, the actuator starts to cool down, and enters the multi-hole suction recovery;

[0031] step 3. During the multi-hole suction recovery stage, the interior of the actuator cavity 105 begins to cool down, and the corresponding gas pressure gradually decreases; under the action of the negative pressure difference inside and outside the jet throat, an suction flow 70 is formed; specifically, the normal temperature and high-density gas outside the actuator is sucked into the interior of the actuator cavity 105 from the convergent jet hole array 102, and mixed with the expanded high-temperature and low-density gas, so that the actuator is restored to its initial working state; after complete recovery, the high-voltage nanosecond pulse power supply 50 can output the next high-voltage pulse to realize the repetitive frequency operation of the actuator.

[0032] Based on the rapid heating effect of nanosecond pulse dielectric barrier discharge, the present invention proposes a new array plasma synthetic jet actuator. Compared with the traditional scheme, the array actuator does not require complex load matching circuit design or power supply optimization design, and has the advantages of simple wiring, low implementation cost, easy large-scale expansion, high operating frequency, and good pulse repeatability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The structure of the array plasma synthetic jet actuator is shown, wherein Figure 1(a) shows the assembly diagram, Figure 1 (b) shows an exploded view;

[0034] Figure 2 The structure of the actuator top cover 10 is shown, wherein Figure 2 (a) shows a top view; Figure 2 (b) shows a bottom view; Figure 2 (c) shows a cross-sectional view of BB; Figure 2 (d) shows a perspective view of the top cover 10 when the bottom surface is placed upward;

[0035] Figure 3 The three working stages of the actuator are shown (AA cross-sectional view), where Figure 3 (a) shows the shock boosting stage; Figure 3 (b) shows the array jet stage; Figure 3 (c) shows the multi-hole suction recovery stage.

[0036] Notes on the attached drawings:

[0037] 0Top cover101Throat outlet102Converging jet hole103Throat inlet104Threaded hole

[0038] 105 exciter cavity 106 shock wave 20 high voltage electrode plate 201 high voltage lead

[0039] 30 insulating dielectric plate 301 positioning through hole 40 grounding metal plate 401 grounding lead

[0040] 402 through hole 50 high voltage nanosecond pulse power supply 60 high speed jet 70 suction flow DETAILED DESCRIPTION

[0041] Figure 1-2 The basic structure of the array plasma synthetic jet actuator for nanosecond pulse dielectric barrier discharge boosting mainly includes four parts: a top cover 10, a high voltage electrode plate 20, an insulating dielectric plate 30 and a grounding metal plate 40.

[0042] The top cover 10 is a rectangular body with a square upper surface and a thickness of 4-6mm (preferably 4mm). It is made of insulating materials such as nylon, polyimide, PEEK or ceramic. The outer contour length and width of the top cover 10 need to be adaptively designed according to the actual application. The typical range is 50mm-500mm. In a preferred embodiment of the present invention, the length and width are 50mm*50mm. The inside of the top cover 10 is hollowed out. A rectangular internal cavity is formed with an open lower part. When combined with the high-voltage electrode plate 20 and the insulating dielectric plate 30, a semi-enclosed, flat square plasma discharge cavity, namely the exciter cavity 105, can be formed, as described in detail later. On the upper surface of the top cover 10, a number of convergent jet holes 102 are processed from bottom to top along a direction perpendicular to the wall. The jet holes 102 are small at the top and large at the bottom. Figure 1-2 In the specific embodiment shown, the jet hole 102 is in the shape of a truncated cone, the upper surface of which is parallel to the lower surface. These jet holes 102 are arranged in an N×M array, serving as the throat for the gas to flow into the exciter cavity 105 from top to bottom and flow out of the exciter cavity 105 from bottom to top. The throat outlet 101 located on the upper surface of the top cover 10 is circular, with a typical diameter range of 1-2 mm (preferably 1.5 mm). The throat inlet 103 located on the upper surface of the exciter cavity 105 (at the lower end of the jet hole 102) is also circular, with a typical diameter range of 2-4 mm (preferably 3 mm). Since the flow rate of gas is conserved when it flows inside the pipeline, the design of the convergent jet hole 102 can accelerate the gas when it flows out of the exciter cavity 105 from bottom to top, which helps to increase the outlet velocity of the plasma synthetic jet. The throat length of the convergent jet hole 102 (i.e., the thickness of the upper wall of the top cover 10) will directly affect the saturation operating frequency of the exciter. If the throat is too long, the exciter suction time will be longer and the saturation working frequency will be lower; if the throat is too short, the structural strength will be insufficient. Taking all factors into consideration, the typical range of the throat length of the convergent jet hole 102 is 1-3 mm (preferably 2 mm). The row spacing and column spacing of the jet hole array 102 should be set to 3-5 times the throat outlet diameter, ranging from 3-15 mm ( Figure 1-2 In the implementation case, it is 5mm). It should be noted that, in addition to being circular, the outlet of the convergent jet hole 102 can also be a long slit hole, a polygonal hole, etc.; the central axis of the jet hole can be perpendicular to the upper surface of the top cover 10, or it can be at a certain angle (i.e., an oblique mouth configuration). As long as the lower inlet area of ​​the jet hole 102 is greater than the upper outlet area, and the cross-sectional area from bottom to top and from the inlet to the outlet is monotonically reduced.

[0043] The electrode plate 20 is made of a thin sheet of metal plate, which is made of a metal material with good electrical conductivity such as copper, silver, and aluminum, and has a typical thickness of 0.01 mm to 1 mm (preferably 0.05 mm). Figure 1-2In the illustrated implementation case, the electrode plate has a dense circular mesh shape, and the diameter of each circular mesh is typically in the range of 2-5 mm (preferably 4 mm). The position of each jet hole array 102 corresponds to a circular mesh, and the axes of the two coincide; the center spacing of adjacent jet holes is the same as the center spacing of adjacent circular meshes. In the illustrated embodiment, the center spacing is 5 mm; the outermost circular mesh is kept at a certain distance from the edge of the electrode plate 20. The mesh shape, diameter, spacing and arrangement are not unique, and those skilled in the art can make appropriate adjustments according to the expected unit area dielectric barrier discharge heating power. In addition, the electrode plate 20 can also be designed into other configurations such as a dense grid, a triangular grid, a honeycomb, or a comb-shaped grid. If it is a square grid, a triangular grid or a honeycomb, the central axis of a single mesh can be aligned with the jet hole, or it can not be aligned. As long as it has the two characteristics of dense and mesh, and the purpose is to increase the plasma heating power and heating uniformity per unit area, it belongs to the scope of the present invention. In terms of technology, the electrode plate 20 can be made of a thin metal plate as a substrate, and a corresponding grid-like configuration can be obtained by chemical etching or laser cutting methods; the electrode plate 20 can also be directly deposited on the insulating dielectric plate 30 by screen printing, mask etching, magnetron sputtering and other processes to form an electrode coating. The laser cutting method or screen printing process with low processing cost is preferred. The length and width of the electrode plate 20 are basically the same as the length and width of the exciter cavity 105, which is convenient for embedding the electrode plate 20 into the top cover 10 from bottom to top.

[0044] The insulating dielectric plate 30 is a thin rectangular body made of insulating material, such as polyimide, nylon, acrylic, PPEK, ceramic or mica. The insulating dielectric plate 30 is used for high voltage insulation to prevent arc discharge between the electrode plate 20 and the grounding metal plate 40. The projection of the insulating dielectric plate 30 on the horizontal plane coincides with the projection of the top cover 10, that is, the length and width of the two are the same. When thin film polyimide is used, the typical thickness range is 0.05-0.2mm (preferably 0.2mm); when other materials are used, the typical thickness range is 0.5-2mm (preferably 1mm).

[0045] The grounding metal plate 40 is a thin rectangular body made of metal materials such as copper, aluminum or stainless steel. Stainless steel is preferred from the perspective of structural strength and raw material price. Its function is to act as a grounding electrode for nanosecond pulse dielectric barrier discharge. The typical thickness range of the grounding metal plate 40 is 2-4 mm, preferably 3 mm. The projection of the grounding metal plate 40 on the horizontal plane coincides with the projection of the top cover 10, that is, the length and width of the insulating dielectric plate 30 and the grounding metal plate 40 are the same as those of the housing 10. It is necessary for technicians in this field to select adaptive parameters according to the application scenario. During installation, the lower surface of the insulating dielectric plate 30 is tightly combined with the upper surface of the grounding metal plate 40 (for example, using double-sided tape or other quick-drying glue for bonding).

[0046] The housing 10, the electrode plate 20, the insulating medium plate 30 and the grounding metal plate 40 are assembled together to form the exciter of the present invention. The assembly of each component can be completed by gluing or threading. Figure 1-2 In the specific embodiment, a threaded docking form is adopted. First, four standard threaded holes 104 are opened on the four top corners of the outer shell 10 along the vertical direction from bottom to top; four positioning through holes 301 are opened at the corresponding positions of the insulating dielectric plate 30; four through holes 402 are opened at the corresponding positions of the top corners of the grounding metal plate. Then, the lower surface of the electrode plate 20 is glued to the upper surface of the insulating dielectric plate 30 by glue. Finally, four screws are used to pass through the through holes 402, the positioning through holes 301 and the threaded holes 104 from bottom to top in turn to realize the assembly and matching of the various components of the exciter.

[0047] The depth of the exciter cavity 105 is determined by the range of gas that can be heated by the nanosecond pulse dielectric barrier discharge in the vertical direction, and the typical value is 1-4 mm (preferably 2 mm). The depth of the exciter cavity 105 refers only to the height of the internal hollow area, and does not include the height of the jet hole 102 and the thickness of the electrode plate 20. The length and width of the exciter cavity 105 can be obtained by subtracting the thickness of the side wall of the top cover from the length and width of the top cover 10. In order to ensure structural strength and facilitate threaded fixation, the side wall thickness of the top cover 10 is typically in the range of 4-10 mm. Figure 1-2 The value is set to 4 mm. Figure 1-2 The length and width of the middle exciter cavity 105 are 42 mm*42 mm respectively.

[0048] The electrode plate 20 , the insulating dielectric plate 30 and the grounding metal plate 40 together form a sandwich-type dielectric barrier discharge structure.

[0049] The electrode plate 20 is connected to an external nanosecond pulse high voltage power supply through a high voltage lead 201, and the grounded metal plate 40 is connected to a common ground with the nanosecond pulse high voltage power supply through a grounding lead 401. After the power is turned on, the air is quickly heated and pressurized by generating a dielectric barrier discharge plasma at all edges of the dense mesh electrode plate 20 (including both the rectangular outer edge and the circular inner edge of each mesh). The traditional plasma synthetic jet exciter uses arc discharge for heating, and the energy is concentrated in an air gap of about 5mm, and the energy of a single pulse can reach more than 100mJ. The single pulse heating energy of nanosecond pulse discharge plasma is generally 10-50mJ, and the energy averaged over the same air gap is much smaller. Therefore, in order to meet the heating energy demand per unit area, the electrode plate 10 must have a dense mesh feature in appearance to greatly increase the total length and discharge power of the discharge plasma per unit area; the final effect is: each edge of the mesh electrode plate (including both the rectangular outer edge and the circular inner edge of each mesh hole) is a tiny rapid discharge heating source, and multiple closely arranged rapid discharge heating sources are combined together to achieve a function similar to that of a traditional "heating wire" heating film, thereby achieving the purpose of rapid and uniform heating of the air inside the exciter cavity 105.

[0050] Combine the following Figure 3 , the working method of the array plasma synthetic jet actuator with nanosecond pulse dielectric barrier discharge impact supercharging is described. The power supply circuit of the array actuator is extremely simple, and only a high-voltage nanosecond pulse power supply 50 is required (output voltage: 10-20kV, maximum repetition frequency: 10kHz). The high-voltage output end of the high-voltage nanosecond pulse power supply 50 is connected to the electrode plate 20 through a lead 201 (not marked), and the ground end is connected to the grounded metal plate 40 through a lead 401. In one jet cycle, the complete working process includes three stages: the impact supercharging stage, the array jet stage and the porous suction recovery stage.

[0051] 1. In the shock boosting stage, the high-voltage nanosecond pulse power supply 50 outputs a high-voltage pulse and applies it to the electrode plate 20. Since there is a tip effect and the electric field strength is concentrated at each edge of the electrode plate 20, the discharge current column is first generated near the edge. Under the action of the rising edge of the high-voltage nanosecond pulse, the current column continues to expand outward along the direction of the electric field, forming a dielectric barrier discharge plasma region near the edge of the electrode. In this region, high-energy electrons ionized from some gas molecules continuously bombard other unionized gas molecules, generating a large number of excited state particles. These excited state particles release a large amount of heat during the extinguishing process, and the temperature of the gas in the plasma region is heated to more than 1000K within the nanosecond time scale, forming a high-temperature gas. Since the heating time scale is extremely short, the high-temperature gas has no time to expand, so the pressure in the plasma region increases sharply, inducing the generation of shock waves 106. The shock wave 106 propagates from the plasma region to the surroundings, and through continuous reflection and convergence, the temperature and pressure of the entire exciter cavity 105 are raised to a level far higher than the atmospheric pressure. At this point, the shock boosting stage is completed.

[0052] 2. In the array jet stage, driven by the high pressure inside the actuator cavity 105, the high-temperature gas is quickly ejected from the convergent jet hole 102 from the inside to the outside, forming a high-speed jet array 60 for flow control in supersonic or other occasions. During the jet ejection process, the pressure inside the actuator cavity 105 will continue to decrease. When the pressure inside the cavity 105 is less than or equal to the atmospheric pressure, the jet ends, the actuator begins to cool, and enters the multi-hole air intake recovery.

[0053] 3. During the multi-hole air intake recovery stage, the interior of the actuator cavity 105 begins to cool down, and the corresponding gas pressure gradually decreases. Under the action of the negative pressure difference inside and outside the jet throat, an air intake flow 70 is formed. Specifically, the normal temperature and high density gas outside the actuator is sucked into the interior of the actuator cavity 105 from the convergent jet hole array 102, and mixed with the expanded high temperature and low density gas, so that the actuator is restored to the initial working state. After full recovery, the high-voltage nanosecond pulse power supply 50 can output the next high-voltage pulse to realize the repetitive frequency operation of the actuator.

[0054] From the above working principle and structural description, it is not difficult to conclude that the main innovation of the present invention in the technical solution is to use dense mesh nanosecond pulse dielectric barrier discharge instead of traditional pulse arc discharge, which can achieve rapid spatial uniform heating of the large-area plasma synthetic jet actuator cavity. The advantages and effects of this solution are reflected in the following aspects:

[0055] 1. Low cost and simple power supply. This solution uses a mature nanosecond pulse power supply on the market, which does not require any power supply modification and load matching circuit design. It greatly saves the power supply R&D cost and can overcome the problem that traditional solutions require large-volume power supplies and complex wiring to power array plasma synthetic jets.

[0056] 2. Easy to expand. Since nanosecond pulse dielectric barrier discharge plasma is a capacitive load, it does not have the disadvantage of the "negative impedance load characteristic" of arc discharge. Therefore, no matter how large the area of ​​the plasma synthetic jet array is, it can be powered by a nanosecond pulse power supply, which makes it easy to expand the area of ​​the exciter jet array according to specific needs in actual flow control applications.

[0057] 3. High synchronization accuracy. Compared with the array plasma synthetic jet based on the "sequential breakdown" principle, the plasma on the entire electrode plate surface in this scheme is generated simultaneously without any delay, and the injection of each jet hole inside the array is strictly synchronized.

[0058] 4. High frequency and good repeatability. Compared with the array plasma synthetic jet based on the principle of "sequential breakdown", the jet frequency of the jet in the present invention is completely determined by the discharge frequency of the high-voltage nanosecond pulse power supply 50 and the resonance frequency of the exciter cavity. There is no front-end charging circuit, and there will be no frequency instability caused by breakdown voltage fluctuations. The typical frequency can reach more than 10kHz.

Claims

1. Array plasma synthetic jet actuator with nanosecond pulse dielectric barrier discharge boost, characterized in that: include: A top cover (10), a high voltage electrode plate (20), an insulating dielectric plate (30) and a grounding metal plate (40); wherein the top cover (10) is a rectangular body made of insulating material, and the upper surface is square; the outer contour length and width of the top cover (10) need to be adaptively designed according to actual applications; the top cover (10) is hollowed out to form a rectangular internal cavity, the lower part of which is open, and when combined with the high voltage electrode plate (20) and the insulating dielectric plate (30), a semi-enclosed, flat square plasma discharge cavity is formed, namely, the exciter cavity (105); on the upper surface of the top cover (10), a plurality of converging grooves are processed from bottom to top along a direction perpendicular to the wall surface. The jet holes (102) are small at the top and large at the bottom; the jet holes (102) are arranged in an N×M array, serving as throats for gas to flow into the exciter cavity (105) from top to bottom and flow out from bottom to top; the throat outlet (101) located on the upper surface of the top cover (10) is circular; the throat inlet (103) located on the upper surface of the exciter cavity (105) is also circular; the central axis of the jet hole is perpendicular to the upper surface of the top cover (10), or forms a certain angle with the normal of the top cover (10); as long as the lower inlet area of ​​the jet hole (102) is greater than the upper outlet area, and the cross-sectional area from the inlet to the outlet decreases monotonically from bottom to top; The electrode plate (20) is made of a thin sheet metal plate; the electrode plate has a dense mesh shape; the position of each jet hole (102) corresponds to a mesh, and the axes of the two coincide; the center spacing of adjacent jet holes is the same as the center spacing of adjacent mesh holes; the outermost circle mesh holes and the edge of the electrode plate (20) are kept at a certain distance; the length and width of the electrode plate (20) are substantially the same as the length and width of the exciter cavity (105), so that the electrode plate (20) can be easily embedded in the top cover (10) from bottom to top; The insulating dielectric plate (30) is a thin rectangular body; the projection of the insulating dielectric plate (30) on the horizontal plane coincides with the projection of the top cover (10), that is, the length and width of the two are the same; The grounding metal plate (40) is a thin rectangular body; the projection of the grounding metal plate (40) on the horizontal plane coincides with the projection of the top cover (10), that is, the length and width of the insulating dielectric plate (30) and the grounding metal plate (40) are the same as those of the top cover (10); during installation, the lower surface of the insulating dielectric plate (30) is tightly combined with the upper surface of the grounding metal plate (40); the top cover (10), the electrode plate (20), the insulating dielectric plate (30) and the grounding metal plate (40) are assembled together in sequence from top to bottom to form an exciter.

2. The array plasma synthetic jet actuator with nanosecond pulse dielectric barrier discharge boosting as claimed in claim 1, characterized in that: The thickness of the top cover (10) is 4-6 mm; the length and width of the outer contour of the top cover (10) are 50 mm-500 mm; The diameter of the throat outlet (101) is in the range of 1-2 mm; the diameter of the throat inlet (103) is in the range of 2-4 mm; The throat length of the convergent jet hole (102) is 1-3 mm; the row spacing and column spacing of the jet hole (102) should be set to 3-5 times the throat outlet diameter, ranging from 3-15 mm.

3. The array plasma synthetic jet actuator with nanosecond pulse dielectric barrier discharge boosting as claimed in claim 1, characterized in that: The top cover (10) has a thickness of 4 mm and is made of insulating materials such as nylon, polyimide, PEEK or ceramics; the outer contour length and width of the top cover (10) are 50 mm*50 mm; The jet hole (102) is in the shape of a truncated cone, and the upper surface of the truncated cone is parallel to the lower surface; The diameter of the throat outlet (101) is 1.5 mm; the diameter of the throat inlet (103) is 3 mm; The throat length of the convergent jet hole (102) is 2 mm.

4. The array plasma synthetic jet actuator with nanosecond pulse dielectric barrier discharge boosting as claimed in claim 1, characterized in that: The thickness of the electrode plate (20) is 0.01 mm to 1 mm; The maximum diameter of the mesh of the electrode plate (20) is 2-5 mm.

5. The array plasma synthetic jet actuator with nanosecond pulse dielectric barrier discharge boosting as claimed in claim 4, characterized in that: The thickness of the electrode plate (20) is 0.05 mm; The maximum mesh diameter of the electrode plate (20) is 4 mm; The electrode plate (20) is a dense square grid, a triangular grid, a honeycomb grid, or a comb-shaped grid.

6. The array plasma synthetic jet actuator with nanosecond pulse dielectric barrier discharge boosting as claimed in claim 1, characterized in that: The insulating dielectric plate (30) is made of insulating materials such as polyimide, nylon, acrylic, PPEK, ceramic or mica; when thin film polyimide is used, the thickness range is 0.05-0.2 mm; when other materials are used, the thickness range is 0.5-2 mm.

7. The array plasma synthetic jet actuator with nanosecond pulse dielectric barrier discharge boosting as claimed in claim 1, characterized in that: The thickness of the grounding metal plate (40) is in the range of 2-4 mm.

8. The array plasma synthetic jet actuator with nanosecond pulse dielectric barrier discharge boosting as claimed in claim 1, characterized in that: The depth of the exciter cavity (105) is 1-4 mm; the thickness of the side wall of the top cover (10) is 4-10 mm.

9. A method for operating a nanosecond pulse dielectric barrier discharge boosted array plasma synthetic jet device, the device being based on the nanosecond pulse dielectric barrier discharge boosted array plasma synthetic jet actuator as claimed in any one of claims 1 to 8, wherein: The high-voltage output end of the high-voltage nanosecond pulse power supply (50) is connected to the electrode plate (20) through a lead (201), and the ground end is connected to the ground metal plate (40) through a lead (401); the characteristic is that within one jet cycle, the complete working process includes three stages: an impact pressurization stage, an array jet stage, and a porous air suction recovery stage; step 1, in the impact pressurization stage, the high-voltage nanosecond pulse power supply (50) outputs a high-voltage pulse and applies it to the electrode plate (20); since there is a tip effect and the electric field strength is concentrated at each edge of the electrode plate (20), a discharge current column is first generated near the edge; under the action of the rising edge of the high-voltage nanosecond pulse, the current column continuously expands outward along the electric field direction, forming a dielectric barrier discharge plasma region near the electrode edge; in this region, high-energy electrons ionized from some gas molecules continuously bombard other non-ionized gas molecules, generating a large number of excited state particles; these excited state particles release a large amount of heat during the extinguishing process, heating the temperature of the gas in the plasma region to form high-temperature gas within the nanosecond time scale; since the heating time scale is extremely short, the high-temperature gas has no time to expand, so the pressure in the plasma region increases sharply, inducing the generation of a shock wave (106); the shock wave (106) propagates from the plasma region to the surroundings, and through continuous reflection and convergence, the temperature and pressure of the entire exciter cavity (105) are raised to a level far higher than the atmospheric pressure; at this point, the impact pressurization stage is completed; Step 2, in the array jet stage, driven by the high pressure inside the actuator cavity (105), the high-temperature gas is quickly ejected from the convergent jet hole (102) from the inside to the outside, forming a high-speed jet array (60) for flow control in supersonic or other occasions; during the jet ejection process, the pressure inside the actuator cavity (105) will continue to decrease; when the pressure inside the cavity (105) is less than or equal to the atmospheric pressure, the jet ends, the actuator starts to cool down, and enters the multi-hole air intake recovery; Step 3. During the multi-hole air intake recovery stage, the interior of the actuator cavity (105) begins to cool down, and the corresponding gas pressure gradually decreases; under the action of the negative pressure difference between the inside and outside of the jet throat, an air intake flow (70) is formed; specifically, the normal temperature and high density gas outside the actuator is sucked into the interior of the actuator cavity (105) from the convergent jet hole (102), and mixed with the expanded high temperature and low density gas, so that the actuator is restored to its initial working state; after complete recovery, the high-voltage nanosecond pulse power supply (50) can output the next high-voltage pulse to realize the repetitive frequency operation of the actuator.

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