CN110891357A - Flow direction multi-channel pulse arc plasma flow control device and method for weakening shock wave intensity - Google Patents
Flow direction multi-channel pulse arc plasma flow control device and method for weakening shock wave intensity Download PDFInfo
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Abstract
The flow control circuit system comprises a flat plate (1), a discharge electrode (2), a cylindrical vertical through hole (3) directly machined on the surface of the flat plate, a pulse power supply (4) and a compression ramp (5). A method for attenuating the intensity of the shock wave by multi-channel pulsed arc plasma excitation is also provided. By flowing to the multi-channel pulsed arc plasma excitation device, the interaction times of the precursor shock wave generated by pulsed arc excitation and the shock wave/boundary layer interference separation shock wave are increased, so that the continuous disturbance of the separation shock wave is realized, and the strength of the separation shock wave is weakened.
Description
Technical Field
The invention relates to a plasma active flow control technology, in particular to a method for weakening the interference intensity of a shock wave/boundary layer and a corresponding flow direction multichannel pulse arc discharge plasma exciter.
Background
In the development of the new generation of turbine-based high-speed combined power, the pneumatic design of an air inlet channel and a cross/supersonic compressor faces the problem of complex shock wave/boundary layer interference. Boundary layer separation under the induction of shock wave strong inverse pressure gradient, low-frequency unstable motion of a flow field structure of an interference region, obvious increase of pressure load and heat load of a local region and obvious sudden rise of downstream turbulence of the interference region are negative effects caused by shock wave/boundary layer interference phenomena, and even cause accident potential such as wing fatigue damage, compressor stalling and surging, air inlet channel non-starting and the like in serious cases. At present, the plasma flow control technology with fast response, high intensity and wide frequency band is an important development direction in the field of shock wave/boundary layer interference control. The plasma excitation has a plurality of control mechanisms such as thermal effect, impact effect, physical property change, frequency coupling and the like, and is an effective way for controlling the interference shock wave strength of the shock wave/boundary layer.
The excitation of the pulsed arc plasma has strong control effect due to the large excitation intensity, and becomes a research hotspot for the interference of the flow control of the plasma by the shock wave/boundary layer. At present, the research of controlling shock wave/boundary layer interference by pulse arc plasma excitation is mostly carried out by adopting a single-channel exciter and a large energy supply mode, the excitation frequency is mostly less than 10kHz, and although a certain flow control effect is obtained, the remarkable non-stationarity is presented. Therefore, the current pulsed arc plasma excitation can not meet the requirements of practical application and needs to be improved.
Disclosure of Invention
Aiming at the problems, the invention provides a flow direction multi-channel pulse arc plasma flow control device, which comprises a flat plate 1, a discharge electrode 2, a cylindrical vertical through hole 3 directly processed on the surface of the flat plate, and a compression slope 5; it is characterized in that
The compression slope 5 is arranged at the rear end of the flat plate 1 to form a flat plate-compression slope structure, a typical compression slope shock wave/boundary layer interference flow field is formed, and the generated separation shock wave is a control object of the control device; the flat plate 1 and the compression slope 5 are both made of insulated acrylic plastic acrylic materials;
processing an even number of cylindrical vertical through holes 3 at the position, close to the compression slope 5, of the flat plate 1, and arranging the cylindrical vertical through holes in an NxM array mode, wherein the number of the cylindrical vertical through holes is N, the number of the cylindrical vertical through holes is M, the number of the cylindrical vertical through holes is non-zero natural number, the number of the cylindrical vertical through holes is an even number, and the specific number of the cylindrical vertical; from the first, a group of discharge channels are formed between every two cylindrical vertical through holes 3 which are adjacent in the spreading direction, NxM discharge electrodes form NxM/2 groups of discharge channels together, the discharge channels of each group are arranged along the flowing direction, the intervals are equal, and the discharge channels are positioned in the center of the flowing direction of the flat plate 1; a discharge electrode 2 is arranged in each cylindrical vertical through hole 3; the cylindrical vertical through hole 3 is divided into an upper through hole and a lower through hole, and the diameter of the lower through hole is larger than that of the upper through hole; an insulating medium cylinder with the size corresponding to that of the lower through hole is arranged in the lower through hole of the cylindrical vertical through hole 3;
the discharge electrode 2 is cylindrical, and the diameter of the discharge electrode is slightly smaller than that of the through hole at the upper part of the cylindrical vertical through hole, so that the discharge electrode can be conveniently inserted; the lower end of the discharge electrode 2 is led out through a lead, and a nanosecond pulse power supply 4 is used for driving the whole circuit to work;
the discharge electrode 2 is inserted into the insulating medium cylinder and penetrates through the insulating medium cylinder, the upper end of the discharge electrode 2 penetrating through the insulating medium cylinder is inserted into the upper through hole of the cylindrical vertical through hole 3, and the lower end of the discharge electrode 2 penetrating through the insulating medium cylinder is connected with a lead; the upper end of the discharge electrode 2 is flush with the upper surface of the flat plate 1 after assembly.
In one embodiment of the present invention, the diameter of the lower through hole of the cylindrical vertical through hole 3 is 4mm to 8 mm; the diameter of the upper through hole is 0.5 mm-2 mm; the angle range of the compression slope 5 is 20-30 degrees; the spanwise distance between the positive and negative discharge electrodes 2 of the discharge channel is 3-6 mm; the flow direction spacing of the discharge channels is 10 mm-20 mm; the electrode material of the discharge electrode 2 is made of high-temperature resistant metal, and the diameter of the discharge electrode is 0.5 mm-3 mm.
In a specific embodiment of the present invention, the lower through-hole diameter of the cylindrical vertical through-hole 3 is 5 mm; the diameter of the upper through hole is 1 mm; the angle of the compression ramp 5 is 24 degrees; the spanwise distance between the positive and negative discharge electrodes 2 of the discharge channel is 5 mm; the flow direction spacing of the discharge channels is 15 mm; the electrode material of the discharge electrode 2 is copper, iron or tungsten, and the diameter of the discharge electrode is 1 mm.
In one embodiment of the present invention, the number of the cylindrical vertical through holes 3 is 10.
The flow control circuit system comprises a flat plate 1, a discharge electrode 2, a cylindrical vertical through hole 3 directly machined on the surface of the flat plate, a pulse power supply 4 and a compression slope 5; it is characterized in that
The compression slope 5 is arranged at the rear end of the flat plate 1 to form a flat plate-compression slope structure, a typical compression slope shock wave/boundary layer interference flow field is formed, and the generated separation shock wave is a control object of the control device; the flat plate 1 and the compression slope 5 are both made of insulated acrylic plastic acrylic materials;
processing an even number of cylindrical vertical through holes 3 at the position, close to the compression slope 5, of the flat plate 1, and arranging the cylindrical vertical through holes in an NxM array mode, wherein the number of the cylindrical vertical through holes is N, the number of the cylindrical vertical through holes is M, the number of the cylindrical vertical through holes is non-zero natural number, the number of the cylindrical vertical through holes is an even number, and the specific number of the cylindrical vertical; from the first, a group of discharge channels are formed between every two cylindrical vertical through holes 3 which are adjacent in the spreading direction, NxM discharge electrodes form NxM/2 groups of discharge channels together, the discharge channels of each group are arranged along the flowing direction, the intervals are equal, and the discharge channels are positioned in the center of the flowing direction of the flat plate 1; a discharge electrode 2 is arranged in each cylindrical vertical through hole 3; the cylindrical vertical through hole 3 is divided into an upper through hole and a lower through hole, and the diameter of the lower through hole is larger than that of the upper through hole; an insulating medium cylinder with the size corresponding to that of the lower through hole is arranged in the lower through hole of the cylindrical vertical through hole 3;
the discharge electrode 2 is cylindrical, and the diameter of the discharge electrode is slightly smaller than that of the through hole at the upper part of the cylindrical vertical through hole, so that the discharge electrode can be conveniently inserted; the lower end of the discharge electrode 2 is led out through a lead, and a nanosecond pulse power supply 4 is used for driving the whole circuit to work;
the discharge electrode 2 is inserted into the insulating medium cylinder and penetrates through the insulating medium cylinder, the upper end of the discharge electrode 2 penetrating through the insulating medium cylinder is inserted into the upper through hole of the cylindrical vertical through hole 3, and the lower end of the discharge electrode 2 penetrating through the insulating medium cylinder is connected with a lead; after assembly, the upper end of the discharge electrode 2 is flush with the upper surface of the flat plate 1;
the working voltage and frequency of the nanosecond pulse power supply 4 are adjustable, and the voltage range is 1 kV-20 kV; the frequency range is 1 Hz-20 kHz;
the pulsed arc discharge circuit is connected as follows: the first positive electrode 2-1 is connected with the positive electrode of the pulse power supply 4, the NxM negative electrode 2-NxM is connected with the negative electrode of the pulse power supply 4, and the other N xM-2 plasma discharge elements are sequentially connected by leads in the following sequence and are connected in series into a discharge loop: the first negative electrode 2-2 is connected with the second positive electrode 2-3, the second negative electrode 2-4 is connected with the third positive electrode 2-5, and so on, the discharging elements of NxM/2 channels are all connected in series into the whole discharging loop.
In one embodiment of the present invention, the diameter of the lower through hole of the cylindrical vertical through hole 3 is 4mm to 8 mm; the diameter of the upper through hole is 0.5 mm-2 mm; the angle range of the compression slope 5 is 20-30 degrees; the spanwise distance between the positive and negative discharge electrodes 2 of the discharge channel is 3-6 mm; the flow direction spacing of the discharge channels is 10 mm-20 mm; the electrode material of the discharge electrode 2 is made of high-temperature resistant metal, and the diameter of the discharge electrode is 0.5 mm-3 mm.
In a specific embodiment of the present invention, the lower through-hole diameter of the cylindrical vertical through-hole 3 is 5 mm; the diameter of the upper through hole is 1 mm; the angle of the compression ramp 5 is 24 degrees; the spanwise distance between the positive and negative discharge electrodes 2 of the discharge channel is 5 mm; the flow direction spacing of the discharge channels is 15 mm; the electrode material of the discharge electrode 2 adopts copper, iron or tungsten, and the diameter of the discharge electrode is 1 mm; the lead and the discharge electrode 2 are sealed and wound by the insulating tape, so that creepage is prevented.
In one embodiment of the present invention, the number of the cylindrical vertical through holes 3 is 10.
In addition, a method for attenuating the intensity of the shock wave by the excitation of the multichannel pulsed arc plasma is also provided, which comprises the following steps:
step 1: the pulse power supply 4 applies high-frequency pulse voltage, and each discharge electrode and the pulse power supply 4 form a loop, which is specifically as follows: the first positive electrode 2-1 is connected with the positive electrode of the pulse power supply 4, the NxM negative electrode 2-NxM is connected with the negative electrode of the pulse power supply 4, and the other N xM-2 plasma discharge elements are sequentially connected by leads in the following sequence and are connected in series into a discharge loop: the first negative electrode 2-2 is connected with the second positive electrode 2-3, the second negative electrode 2-4 is connected with the third positive electrode 2-5, and the rest is done in sequence, and the discharging elements of NxM/2 channels are connected in series and enter the whole discharging loop; forming a potential difference between the two ends of the first positive electrode 2-1 and the first negative electrode 2-2, forming a potential difference between the two ends of the second positive electrode 2-3 and the second negative electrode 2-4, and so on;
step 2: under the action of potential difference, a plasma discharge channel between the first positive electrode 2-1 and the first negative electrode 2-2 is established, and pulse arc discharge is formed on the surface of the flat plate 1; then, plasma discharge elements in the loop are sequentially broken down according to the sequence of a first positive electrode 2-1 and a first negative electrode 2-2, and a second positive electrode 2-3 and a second negative electrode 2-4. to finally form N multiplied by M/2 pulse arc discharge channels, generate N multiplied by M/2 precursor shock waves 6, and simultaneously heat air on the surface of the flat plate 1 to form a hot air mass 7;
and step 3: a compression slope 5 with an angle of preferably 24 degrees is arranged at the downstream of the last group of discharge channels, under the condition of supersonic velocity incoming flow, the shock waves 6 flowing to the five precursor channels are transmitted to the downstream of the flat plate, and interact with the separated shock waves in the shock wave/boundary layer interference area in front of the compression slope 5 in sequence, so that the pulse arc excitation frequency and the discharge channel interval are reasonably controlled, and when the interaction between the fifth precursor shock waves 6 generated by the first pulse and the shock waves does not disappear, the first precursor shock waves 6 generated by the second pulse begin to act on the shock waves, thereby achieving the continuous disturbance effect on the shock waves and weakening the shock wave intensity.
By flowing to the multi-channel pulsed arc plasma excitation device, the interaction times of the precursor shock wave generated by pulsed arc excitation and the shock wave/boundary layer interference separation shock wave are increased, so that the continuous disturbance of the separation shock wave is realized, and the strength of the separation shock wave is weakened.
Drawings
FIG. 1 is a schematic diagram of a flow-direction multi-channel pulsed arc plasma exciter and its circuit connections;
FIG. 2 is a schematic diagram of the excitation and shock wave action of a flow-through multi-channel pulsed arc plasma, wherein FIG. 2(a) shows the interaction process of the flow-through multi-channel pulsed arc plasma excitation and shock wave, and FIG. 2(b) shows the excitation timing between pulse 1 and pulse 2;
fig. 3 is a diagram showing the effect of reducing the intensity of the shock wave by excitation of the multi-channel pulsed arc plasma according to the embodiment of the present invention, and fig. 3(a) to 3(h) respectively show the texture images of the shock wave after excitation is applied, wherein t is 0 μ s to 550 μ s;
reference numerals: 1. the method comprises the following steps of (1) an acrylic flat plate (hereinafter referred to as a 'flat plate'), 2. a pulse arc discharge electrode (hereinafter referred to as a 'discharge electrode'), 3. a cylindrical vertical through hole, 4. a high-frequency nanosecond pulse power supply (hereinafter referred to as a 'pulse power supply'), 5. a compression slope, 6. a precursor shock wave and 7. a hot air mass.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in more detail below with reference to the accompanying drawings of the present invention. In the drawings, like reference numerals refer to like elements throughout. The described embodiments are only some, but not all embodiments of the invention. The technical solution of the present invention is described in detail below with reference to the accompanying drawings and examples.
As shown in FIG. 1, the present invention provides a flow control device for multi-channel pulsed arc plasma, which comprises a flat plate 1, a discharge electrode 2, a cylindrical vertical through hole 3 directly processed on the surface of the flat plate, a pulse power supply 4 and a compression ramp 5. The flat plate 1 and the compression slope 5 are both made of insulating acrylic plastic acrylic materials. The compression slope 5 is arranged at the rear end (namely the right end in the figure) of the flat plate 1 to form a typical flat plate-compression slope structure, a typical compression slope shock wave/boundary layer interference flow field can be formed, and the generated separation shock wave is a control object of the control device. An even number of cylindrical vertical through holes 3 are machined in the plate 1, and a discharge electrode 2 is placed in each cylindrical vertical through hole 3. The cylindrical vertical through hole 3 is divided into an upper through hole and a lower through hole, the diameter of the lower through hole is larger and is 4 mm-8 mm, and the preferred diameter is 5 mm; the diameter of the upper through hole is smaller and is 0.5 mm-2 mm, and the preferred diameter is 1 mm. In a specific embodiment of the present invention, the number of the cylindrical vertical through holes 3 is 10, from the first, a group of discharge channels is formed between every two cylindrical vertical through holes 3 extending to the adjacent direction, 5 groups of discharge channels are formed by 10 discharge electrodes, the groups of discharge channels are arranged along the flow direction with equal intervals, and the discharge channels are located at the center of the flow direction of the flat plate 1. The discharge electrode 2 is cylindrical in shape, and the diameter of the discharge electrode is slightly smaller than that of the through hole at the upper part of the cylindrical vertical through hole, so that the discharge electrode can be conveniently inserted. The lower end of the discharge electrode 2 is led out through a lead and is connected with the positive electrode and the negative electrode of a nanosecond pulse power supply 4 (Zhang Xiaoning, Lidaghun, a parameter-adjustable negative high-voltage pulse power supply device and a parameter adjusting method, CN201810322511), so that the whole circuit is driven to work.
In one embodiment of the present invention, the discharge electrode 2 is inserted into a teflon cylinder, the discharge electrode 2 penetrates through the teflon cylinder, the teflon cylinder is fixed in a lower through hole of the cylindrical vertical through hole 3, an upper end of the discharge electrode 2 penetrating through the teflon cylinder is inserted into an upper through hole of the cylindrical vertical through hole 3, a lower end of the discharge electrode 2 penetrating through the teflon cylinder is connected with a lead wire, and the lead wire and the electrode are wrapped by an insulating tape to prevent creepage. The upper end of the discharge electrode 2 is flush with the upper surface of the flat plate 1 after assembly.
As shown in fig. 1, the pulsed arc discharge circuit is connected as follows: the first positive electrode 2-1 is connected with the positive electrode of the pulse power supply 4, the fifth negative electrode 2-10 is connected with the negative electrode of the pulse power supply 4, and the other 8 plasma discharge elements are sequentially connected by leads in the following sequence and are connected in series into a discharge loop: the first negative electrode 2-2 is connected with the second positive electrode 2-3, the second negative electrode 2-4 is connected with the third positive electrode 2-5, and so on, the discharging elements of 5 channels are connected in series to enter the whole discharging loop.
In one embodiment of the invention, the angle of the compression ramp 5 is in the range of 20 to 30 degrees, preferably 24 degrees.
In one embodiment of the invention, the spanwise spacing of the positive and negative discharge electrodes 2 of the discharge channel is 3mm to 6mm, preferably 5 mm; the flow direction spacing of the discharge channels (two adjacent positive electrodes) is 10mm to 20mm, preferably 15 mm.
In one embodiment of the present invention, the electrode material of the discharge electrode 2 is made of high temperature resistant copper, iron, tungsten metal, preferably tungsten metal; the diameter of the discharge electrode is 0.5mm to 3mm, preferably 1 mm.
In a specific embodiment of the invention, the working voltage and frequency of the nanosecond pulse power supply 4 are adjustable, and the voltage range is 1 kV-20 kV, preferably 20 kV; the frequency range is 1Hz to 20kHz, preferably 5 kHz.
The invention also provides a method for weakening the intensity of the shock wave by exciting the multi-channel pulsed arc plasma, which comprises the following steps:
step 1: the pulse power supply 4 applies high-frequency pulse voltage, and each discharge electrode and the pulse power supply 4 form a loop, which is specifically as follows: the first positive electrode 2-1 is connected with the positive electrode of the pulse power supply 4, the fifth negative electrode 2-10 is connected with the negative electrode of the pulse power supply 4, and the other 8 plasma discharge elements are sequentially connected by leads in the following sequence and are connected in series into a discharge loop: the first negative electrode 2-2 is connected with the second positive electrode 2-3, the second negative electrode 2-4 is connected with the third positive electrode 2-5, and so on, the discharging elements of 5 channels are connected in series to enter the whole discharging loop. And a potential difference is formed between the two ends of the first positive electrode 2-1 and the first negative electrode 2-2, a potential difference is formed between the two ends of the second positive electrode 2-3 and the second negative electrode 2-4, and the like.
Step 2: under the action of potential difference, a plasma discharge channel between the first positive electrode 2-1 and the first negative electrode 2-2 is established, and pulse arc discharge is formed on the surface of the flat plate 1; then, plasma discharge elements in the loop are sequentially broken down according to the sequence of a first positive electrode 2-1 and a first negative electrode 2-2, and a second positive electrode 2-3 and a second negative electrode 2-4. finally, 5 pulse arc discharge channels are formed, 5 precursor shock waves 6 are generated, and air on the surface of the flat plate 1 is heated to form a hot air mass 7;
and step 3: a compression slope 5 with an angle of preferably 24 degrees is arranged at the downstream of the last group of discharge channels, under the condition of supersonic velocity incoming flow, the shock waves 6 flowing to the five precursor channels are transmitted to the downstream of the flat plate, and interact with the separated shock waves in the shock wave/boundary layer interference area in front of the compression slope 5 in sequence, so that the pulse arc excitation frequency and the discharge channel interval are reasonably controlled, and when the interaction between the fifth precursor shock waves 6 generated by the first pulse and the shock waves does not disappear, the first precursor shock waves 6 generated by the second pulse begin to act on the shock waves, thereby achieving the continuous disturbance effect on the shock waves and weakening the shock wave intensity.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
With reference to fig. 1, the plate 1 and the compression ramp 5 form a typical plate-compression ramp structure, forming a typical compression ramp shock wave/boundary layer interference flow field, and the angle of the compression ramp 5 is 24 degrees (the most typical shock wave/boundary layer interference configuration internationally). The last group of discharge channels (fifth positive electrodes 2-9 and fifth negative electrodes 2-10) is installed upstream of the compression ramp 5, and is 25mm away from the head of the compression ramp 5.
The pulse power supply 4 applies pulse voltage of 20kV, excitation frequency of 10kHz and pulse width of 1000ns to the circuit loop.
The first positive electrode 2-1 and the first negative electrode 2-2 form arc discharge on the upper surface of the flat plate 1 under the excitation of voltage, and the like until the fifth positive electrode 2-9 and the fifth negative electrode 2-10 also generate arc discharge, all discharge elements of each stage are broken down to form 5 arc discharge channels, and precursor shock waves 6 and hot air masses 7 are generated.
Referring to fig. 2, the excitation and the shocking action of the multi-channel pulsed arc plasma are explained in detail, the total length L of the five groups of exciters is 60mm, and the interval L1 between two adjacent exciters is 15mm, as labeled in fig. 2 (a).
The experiment was carried out under conditions of incoming flow Mach2.0, with a theoretical velocity v of 520 m/s. The velocity of the precursor shock wave generated by pulse excitation and propagated downstream along the main flow is assumed to be consistent with the main flow. The time interval between two adjacent exciters acting on the separated shock wave satisfies the following relationship:
f＝1/t＝v/L1
where t is the time interval and f is the response frequency inside the pulse. The action time interval of two adjacent exciters can be calculated to be 28.8 mus, converted to a frequency equivalent to 30kHz, as shown in fig. 2 (b). That is, in a flow-through multichannel arrangement, the perturbation frequency for the decoupled shock wave inside a single pulse is 30 kHz. In this case, when the fifth set of precursor shock waves 6-5 of the first pulse act on the separation laser, the excitation action closest to the flow direction has elapsed by Δ t-4 t-115 μ s. And the time interval between two pulses is 100 mus < 115 mus. That is, pulse 2 has acted on the shock wave before pulse 1 has disappeared. It can be seen that the combination of the multi-channel and flow direction layouts realizes the mutual cooperation of the space layout and the time response, shortens the time interval of the disturbance effect and obtains a more lasting effect.
As can be seen from fig. 3, the precursor shock wave 6 is generated immediately after discharge at t ═ 10 μ s, and in the first pulse at t ═ 50 μ s, the precursor shock wave 6 penetrates into the separated shock wave in a row, and the shock wave does not change significantly except for the disturbance point where the oblique shock wave starts to appear with significant distortion, and after the second disturbance, the shock wave foot deformation is aggravated, and in the same snapshot, the shock wave intensity shows a downward trend in the interaction region. In subsequent perturbations, the shock leg almost disappeared, indicating that the intensity of the split shock was attenuated by the flow-to-multi-channel pulsed arc plasma excitation. Further, at t 550 μ s, it was found that the split shock wave was divided into two parts to form a λ wave system.
The description and application of the present invention are illustrative, and are not intended to limit the scope of the invention to the embodiments described above. Variations and modifications of the embodiments disclosed herein are possible, and alternative and equivalent various components of the embodiments are known to those of ordinary skill in the art. The present invention may be embodied in other forms, structures, arrangements, proportions, and with other components, materials, and parts, without departing from the spirit or essential characteristics thereof. Other variations and modifications of the embodiments disclosed herein may be made without departing from the scope and spirit of the invention.
Claims (9)
1. A flow control device of multi-channel pulse arc plasma comprises a flat plate (1), a discharge electrode (2), a cylindrical vertical through hole (3) directly processed on the surface of the flat plate, and a compression slope (5); it is characterized in that
The compression slope (5) is arranged at the rear end of the flat plate (1) to form a flat plate-compression slope structure, a typical compression slope shock wave/boundary layer interference flow field is formed, and a generated separation shock wave is a control object of the control device; the flat plate (1) and the compression slope (5) are both made of insulated acrylic plastic acrylic materials;
processing even cylindrical vertical through holes (3) on the flat plate (1) close to the compression slope (5) and arranging in an NxM array mode, wherein the flow direction is N, the spreading direction is M, N is a non-zero natural number, M is an even number, and the specific number is determined according to the requirement; from the first, a group of discharge channels are formed between every two cylindrical vertical through holes (3) which are adjacent in the spreading direction, NxM discharge electrodes form NxM/2 groups of discharge channels, all groups of discharge channels are arranged along the flowing direction, the intervals are equal, and the discharge channels are positioned in the center of the flowing direction of the flat plate (1); a discharge electrode (2) is arranged in each cylindrical vertical through hole (3); the cylindrical vertical through hole (3) is divided into an upper through hole and a lower through hole, and the diameter of the lower through hole is larger than that of the upper through hole; an insulating medium cylinder with the size corresponding to that of the lower through hole is arranged in the lower through hole of the cylindrical vertical through hole (3);
the discharge electrode (2) is cylindrical, and the diameter of the discharge electrode is slightly smaller than that of the through hole at the upper part of the cylindrical vertical through hole, so that the discharge electrode can be conveniently inserted; the lower end of the discharge electrode (2) is led out through a lead;
the discharge electrode (2) is inserted into the insulating medium cylinder and penetrates through the insulating medium cylinder, the upper end of the discharge electrode (2) penetrating through the insulating medium cylinder is inserted into the upper through hole of the cylindrical vertical through hole (3), and the lower end of the discharge electrode (2) penetrating through the insulating medium cylinder is connected with a lead; the upper end of the discharge electrode (2) is flush with the upper surface of the flat plate (1) after assembly.
2. The flow direction multi-channel pulsed arc plasma flow control device according to claim 1, characterized in that the diameter of the lower through hole of the cylindrical vertical through hole (3) is 4mm to 8 mm; the diameter of the upper through hole is 0.5 mm-2 mm; the angle range of the compression slope (5) is 20-30 degrees; the spanwise distance between the positive and negative discharge electrodes (2) of the discharge channel is 3-6 mm; the flow direction spacing of the discharge channels is 10 mm-20 mm; the electrode material of the discharge electrode (2) is made of high-temperature resistant metal, and the diameter of the discharge electrode is 0.5 mm-3 mm.
3. A flow direction multi-channel pulsed arc plasma flow control device according to claim 2, characterized in that the lower through hole diameter of the cylindrical vertical through hole (3) is 5 mm; the diameter of the upper through hole is 1 mm; the angle of the compression slope (5) is 24 degrees; the spanwise distance between the positive and negative discharge electrodes (2) of the discharge channel is 5 mm; the flow direction spacing of the discharge channels is 15 mm; the electrode material of the discharge electrode (2) adopts copper, iron or tungsten, and the diameter of the discharge electrode is 1 mm.
4. A flow direction multi-channel pulsed arc plasma flow control device according to claim 1, characterized in that the number of cylindrical vertical through holes (3) is 10.
5. A flow direction multi-channel pulse arc plasma flow control circuit system comprises a flat plate (1), a discharge electrode (2), a cylindrical vertical through hole (3) directly machined on the surface of the flat plate, a pulse power supply (4) and a compression slope (5); it is characterized in that
The compression slope (5) is arranged at the rear end of the flat plate (1) to form a flat plate-compression slope structure, a typical compression slope shock wave/boundary layer interference flow field is formed, and a generated separation shock wave is a control object of the control device; the flat plate (1) and the compression slope (5) are both made of insulated acrylic plastic acrylic materials;
processing even cylindrical vertical through holes (3) on the flat plate (1) close to the compression slope (5) and arranging in an NxM array mode, wherein the flow direction is N, the spreading direction is M, N is a non-zero natural number, M is an even number, and the specific number is determined according to the requirement; from the first, a group of discharge channels are formed between every two cylindrical vertical through holes (3) which are adjacent in the spreading direction, NxM discharge electrodes form NxM/2 groups of discharge channels, all groups of discharge channels are arranged along the flowing direction, the intervals are equal, and the discharge channels are positioned in the center of the flowing direction of the flat plate (1); a discharge electrode (2) is arranged in each cylindrical vertical through hole (3); the cylindrical vertical through hole (3) is divided into an upper through hole and a lower through hole, and the diameter of the lower through hole is larger than that of the upper through hole; an insulating medium cylinder with the size corresponding to that of the lower through hole is arranged in the lower through hole of the cylindrical vertical through hole (3);
the discharge electrode (2) is cylindrical, and the diameter of the discharge electrode is slightly smaller than that of the through hole at the upper part of the cylindrical vertical through hole, so that the discharge electrode can be conveniently inserted; the lower end of the discharge electrode (2) is led out through a lead, and a nanosecond pulse power supply (4) is used for driving the whole circuit to work;
the discharge electrode (2) is inserted into the insulating medium cylinder and penetrates through the insulating medium cylinder, the upper end of the discharge electrode (2) penetrating through the insulating medium cylinder is inserted into the upper through hole of the cylindrical vertical through hole (3), and the lower end of the discharge electrode (2) penetrating through the insulating medium cylinder is connected with a lead; after assembly, the upper end of the discharge electrode (2) is flush with the upper surface of the flat plate (1);
the working voltage and frequency of the nanosecond pulse power supply (4) are adjustable, and the voltage range is 1 kV-20 kV; the frequency range is 1 Hz-20 kHz;
the pulsed arc discharge circuit is connected as follows: the first positive electrode (2-1) is connected with the positive electrode of the pulse power supply (4), the NxM negative electrode (2-NxM) is connected with the negative electrode of the pulse power supply (4), and the other N xM-2 plasma discharge elements are sequentially connected by leads in sequence and are connected in series into a discharge loop: the first negative electrode (2-2) is connected with the second positive electrode (2-3), the second negative electrode (2-4) is connected with the third positive electrode (2-5), and the rest is repeated, and the discharging elements of NxM/2 channels are connected in series and enter the whole discharging loop.
6. The flow direction multi-channel pulsed arc plasma flow control circuitry of claim 5, characterized in that the lower through hole diameter of the cylindrical vertical through hole (3) is 4mm to 8 mm; the diameter of the upper through hole is 0.5 mm-2 mm; the angle range of the compression slope (5) is 20-30 degrees; the spanwise distance between the positive and negative discharge electrodes (2) of the discharge channel is 3-6 mm; the flow direction spacing of the discharge channels is 10 mm-20 mm; the electrode material of the discharge electrode (2) is made of high-temperature resistant metal, and the diameter of the discharge electrode is 0.5 mm-3 mm.
7. Flow direction multi-channel pulsed arc plasma flow control circuitry as claimed in claim 5, characterized in that the lower through hole diameter of the cylindrical vertical through hole (3) is 5 mm; the diameter of the upper through hole is 1 mm; the angle of the compression slope (5) is 24 degrees; the spanwise distance between the positive and negative discharge electrodes (2) of the discharge channel is 5 mm; the flow direction spacing of the discharge channels is 15 mm; the electrode material of the discharge electrode (2) adopts copper, iron or tungsten, and the diameter of the discharge electrode (2) is 1 mm; the lead and the discharge electrode (2) are sealed and wound through the insulating tape, so that creepage is prevented.
8. The flow direction multi-channel pulsed arc plasma flow control circuitry of claim 5, characterized in that the number of cylindrical vertical vias (3) is 10.
9. A method for attenuating shock wave intensity by flow direction multi-channel pulsed arc plasma excitation, comprising:
step 1: the pulse power supply (4) applies high-frequency pulse voltage, and each discharge electrode and the pulse power supply (4) form a loop, which comprises the following specific steps: the first positive electrode (2-1) is connected with the positive electrode of the pulse power supply (4), the NxM negative electrode (2-NxM) is connected with the negative electrode of the pulse power supply (4), and the other N xM-2 plasma discharge elements are sequentially connected by leads in sequence and are connected in series into a discharge loop: the first negative electrode (2-2) is connected with the second positive electrode (2-3), the second negative electrode (2-4) is connected with the third positive electrode (2-5), and the rest is done in sequence, and the discharging elements of NxM/2 channels are connected in series and enter the whole discharging loop; forming a potential difference between the two ends of the first positive electrode (2-1) and the first negative electrode (2-2), forming a potential difference between the two ends of the second positive electrode (2-3) and the second negative electrode (2-4), and so on;
step 2: under the action of potential difference, a plasma discharge channel between the first positive electrode (2-1) and the first negative electrode (2-2) is established, and pulse arc discharge is formed on the surface of the flat plate (1); then, sequentially breaking down plasma discharge elements in the loop according to the sequence of a first positive electrode (2-1) and a first negative electrode (2-2), and a second positive electrode (2-3) and a second negative electrode (2-4), finally forming N multiplied by M/2 pulse arc discharge channels, generating N multiplied by M/2 precursor shock waves (6), and simultaneously heating the air on the surface of the flat plate (1) to form a hot air mass (7);
and step 3: a compression slope (5) with an angle of preferably 24 degrees is installed at the downstream of the last group of discharge channels, under the condition of supersonic velocity incoming flow, five precursor shock waves (6) flow to the downstream of the flat plate and are transmitted to the downstream of the flat plate, the five precursor shock waves interact with the separated shock waves in a shock wave/boundary layer interference area in front of the compression slope (5), the pulse arc excitation frequency and the distance between the discharge channels are reasonably controlled, and when the interaction between the fifth precursor shock wave (6) generated by the first pulse and the shock waves does not disappear, the first precursor shock wave (6) generated by the second pulse starts to act on the shock waves, so that the continuous disturbance effect on the shock waves is achieved, and the shock wave intensity is weakened.
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