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CN-116614927-B - Grid-shaped plasma exciter for turbulence resistance reduction

CN116614927BCN 116614927 BCN116614927 BCN 116614927BCN-116614927-B

Abstract

The grid-shaped plasma exciter for turbulence drag reduction comprises a high-voltage electrode (11), a dielectric layer (13), a low-voltage electrode (12) and an insulating substrate (14) from top to bottom, wherein the high-voltage electrode (11) is in a staggered grid shape, the high-voltage electrode (12) is in an array square shape, and the central position of each square corresponds to the central position of each grid hole of the high-voltage electrode (11). The grid-shaped net-shaped plasma exciter solves the problems of high processing difficulty, high cost, complex structure, limited effective drag reduction wind speed range of a common plasma exciter and the like in the traditional flow control technology. Because the excitation intensity and the working mode of the plasma exciter are controlled by the electric signals, the plasma exciter is beneficial to realizing the self-adaptive adjustment of different environmental parameters and realizing the intellectualization. The invention has friction drag reduction and flow separation control, and can greatly improve the performance of a military low-speed unmanned aerial vehicle, including stall prevention under a large attack angle, widening of a flight safety boundary, improvement of a flight range and the like.

Inventors

  • Zong Haohua
  • FANG ZIQI
  • WU YUN
  • SU ZHI
  • LIANG HUA

Assignees

  • 中国人民解放军空军工程大学

Dates

Publication Date
20260512
Application Date
20230411

Claims (9)

  1. 1. The grid-shaped plasma exciter for reducing drag of turbulence comprises a high-voltage electrode (11), a dielectric layer (13), a low-voltage electrode (12) and an insulating substrate (14) from top to bottom, The dielectric layer (13) is a rectangular sheet; The high-voltage electrodes (11) are in a staggered grid shape and are arranged on the upper surface of the medium layer (13), warps and wefts of the grid are long strips, the warps and wefts are respectively parallel to four sides of the medium layer (13), the warps and wefts of the outermost layer are respectively kept at a certain distance from the four sides of the medium layer (13), a plurality of grid holes are formed between the warps and the wefts, and all the grid holes are square; The low-voltage electrodes (12) are arranged on the lower surface of the medium layer (13) in the form of square blocks of the array, are positioned in an interlayer of the medium layer (13) and the insulating substrate (14), are not contacted with air except for wiring positions of the low-voltage electrodes (12), and are completely corresponding to the central positions of grid holes of the high-voltage electrodes (11), and four edges of each square block in the low-voltage electrodes (12) are aligned with the edges of the strip-shaped warps and wefts of the high-voltage electrodes without overlapping, namely, the square blocks just fill the grid holes; The insulating substrate (14) is arranged at the bottom of the dielectric layer (13), and the projection of the insulating substrate on the horizontal plane is coincident with the projection of the dielectric layer (13).
  2. 2. The turbulence-oriented grid-shaped plasma exciter for drag reduction according to claim 1, wherein the grid-shaped plasma exciter (1) has a length and width ranging from 50 to 500mm, the high-voltage electrode (11) has a warp and weft width ranging from 0.5 to 3mm, the low-voltage electrode (12) has a side length ranging from 5 to 20mm, and the high-voltage electrode (11) and the low-voltage electrode (12) have a thickness ranging from 50 to 100 μm.
  3. 3. The turbulence-oriented grid-shaped plasma exciter for reducing drag as claimed in claim 2, characterized in that the width of the warp and weft of the high-voltage electrode (11) of the plasma exciter (1) is 1mm, the side length of each square in the low-voltage electrode (12) is 10mm, the thickness of the high-voltage electrode (11) and the low-voltage electrode (12) is 75 μm.
  4. 4. The grid-shaped plasma exciter for turbulent drag reduction as claimed in claim 1, wherein the dielectric layer (13) is made of polyimide, and is glued with the high-voltage electrode (11) and the high-voltage electrode (12) through acrylic glue, the thickness of the dielectric layer (13) ranges from 100 μm to 250 μm, and the thickness of the insulating substrate (14) ranges from 50 μm to 200 μm.
  5. 5. The turbulence-drag-reducing oriented square grid plasma exciter of claim 1, characterized in that the thickness of the dielectric layer (13) is 200 μm and the thickness of the insulating substrate (14) is 100 μm.
  6. 6. The turbulence-oriented, drag-reducing, grid-like plasma actuator of claim 1, made by a flexible circuit board process.
  7. 7. A turbulence drag reduction oriented grid mesh plasma exciter device based on the turbulence drag reduction oriented grid mesh plasma exciter of any of claims 1 to 5, characterized in that the positive pole of the plasma power source (2) is connected to the high voltage electrode (11) and the negative pole is commonly grounded to the high voltage electrode (12).
  8. 8. The grid-shaped plasma exciter device for turbulence drag reduction according to claim 7, wherein the plasma power supply (2) can modulate the output sine voltage waveform besides outputting a steady sine wave, and change parameters such as discharge voltage, discharge frequency, pulse frequency, duty ratio and the like so as to realize excitation with different intensities or vertical jet pulse excitation with different frequencies.
  9. 9. A working process of a grid-shaped plasma exciter device facing turbulence drag reduction is characterized in that when an alternating current sine wave plasma power supply is adopted, after the grid-shaped plasma exciter (1) is connected with the plasma power supply (2), a strong electric field is formed near the longitude and latitude edges of grid-shaped high-voltage electrodes (11), a small amount of free electrons in air accelerate in the electric field and collide with a neutral example at a high speed, gas molecules are ionized to generate more positive and negative ions, an unbalanced discharge plasma area is generated between the two electrodes, charged particles do directional acceleration motion under the action of the electric field, namely, the plasma pneumatic excitation is performed, excitation induces a start vortex, then the excitation is performed into a near-wall jet, and air currents accelerated from the periphery of square grid-shaped low-voltage electrodes (12) are induced in the inside each grid hole, the left and right air currents collide and fuse in the middle part from the view of a cross section, so that vertical jet flow is generated in the arch direction, the inner surfaces of the holes are combined together, namely, the surface of the grid holes is the surface of the grid, the surface is the near-shaped near-wall, the surface is the near-wall is generated, the surface of the near-wall turbulence is generated, and the turbulence is similar to the surface of a fluid jet flow is generated, and the surface is generated in a near-plane turbulence surface array, and the turbulence surface is generated, and the turbulence surface is similar to a turbulence surface is generated.

Description

Grid-shaped plasma exciter for turbulence resistance reduction Technical Field The invention relates to the technical field of plasma flow control, in particular to a novel-configuration plasma exciter for friction drag reduction of a turbulent boundary layer. Background High lift drag reduction has been the pursuit of aerodynamic design of aircraft. The friction resistance of the large-sized conveyor and the large-aspect ratio unmanned aerial vehicle is approximately 50% of the total resistance in the cruising flight stage. Therefore, the cruise lift-drag ratio of the aircraft can be improved by reducing the friction resistance, particularly the turbulent friction resistance, so that the oil consumption of an engine is reduced, the range and the endurance of the aircraft are improved, and the energy consumption is saved. The boundary layer flow drag reduction control technology is mainly divided into a passive control mode and an active control mode. Typical flow control means are small ribs, grooves, micro-blowing arrays, etc. The small ribs and the grooves are used as a passive control technology to obtain a certain drag reduction effect, but the working range is limited, the groove structure size needs to be developed to the micron level in the high-speed and high-Reynolds number flow, the processing mode is more complex, and the cost is increased. The prior researches show that the micro-blowing array realizes friction drag reduction in a turbulent boundary layer, but has the problems of complex air supply system, difficult maintenance of porous medium and the like. Compared with other modes, the novel active flow control technology has the advantages of simple structure, quick response, wide frequency band and the like. The application of existing plasma exciters to turbulent drag reduction can be broadly divided into three categories, namely flow direction jet, spanwise jet (CN 111465162a, turbulent boundary layer plasma drag reduction system and method, huang Zhiwei Zhou Yucheng schottky Ouyang Teng) and spanwise shock (CN 115023017a, an oscillating discharge plasma exciter for turbulent boundary layer drag reduction control, wugao super Yan Rihua Zheng Haibo Wang Yuling), the basic idea of which is to interact with the near wall flow structure of the boundary layer by inducing wall parallel jets. Although the three plasma exciters all achieve a certain drag reduction effect, the range of the active incoming wind speed is mostly below 15 m/s. In order to further improve the flow control drag reduction effect, the thinking paradigm of traditional flow direction/direction-spreading plasma jet drag reduction must be eliminated, and a novel plasma exciter is designed to solve the technical problems. The plasma exciter configuration may be combined from different electrode patterns. Most of the configurations applied to turbulent drag reduction are described in patent CN113068294A, CN115023017A and CN109587920A, and the high-voltage electrode is comb-shaped, strip-shaped or wire-shaped, and the high-voltage electrode is a strip-shaped rectangular surface. Other high voltage electrodes are circular, square, mesh, and rectangular as described in CN112399694A, CN107914865A, CN101511146A, CN111225486a and CN112607032 a. The effect of vertical jet disturbance on the wall surface cannot be achieved by adopting a conventional electrode configuration, and a square-grid-configuration plasma exciter can meet the requirements. Plasma actuators similar to the checkered configuration are mentioned in both patent CN111432543A, CN111298974A, CN111328955A, CN203554775U and CN108016622 a. However, the patents CN111432543A, CN111298974A, CN111328955A and CN108016622A mainly focus on biomedical plasma treatment, plasma sterilization and disinfection and aircraft deicing fields, and are not applicable to turbulent friction drag reduction. The upper surface electrode and the lower surface electrode are overlapped in the configuration designed in the patent CN203554775U, so that the parasitic capacitance of the exciter is large, a large part of the power supply is reactive power consumption in the working process, and the working efficiency is low. The application of the checkered shape in CN108016622a is mainly to increase the plasma length per unit area, thereby improving the heat generation and anti-icing effect of the exciter, and is not suitable for turbulent friction drag reduction, and its expected function is yet to be verified. Table 1 lists prior art features and applicable scenarios. TABLE 1 prior art characteristics and applicable scenarios In view of this, there is a need for further improvements to square mesh actuators that make them more suitable for use in the field of turbulent drag reduction. Disclosure of Invention Aiming at the problems existing in the prior art, the invention provides a grid-shaped plasma exciter for turbulence drag reduction, which comprises a high-voltage electrode 11, a dielectric lay