CN112954875B - A drag reduction device based on negative pressure sliding plasma discharge - Google Patents

Abstract

A drag reducing device based on negative pressure sliding plasma discharge disclosed by the present invention includes a mounting plate on which several plasma discharge units arranged in an array without gaps are installed; the plasma discharge unit includes positive six The ribbed tubular dielectric layer is provided with AC electrodes and pulsed DC electrodes along the inner wall surface of the regular hexagonal tubular dielectric layer, and buried electrodes are buried in the regular hexagonal tubular dielectric layer corresponding to the AC electrodes and the pulsed DC electrodes. The buried electrodes, AC electrodes and The pulsed DC electrodes are all positive hexagonal tubes; several buried electrodes on the installation plate are connected in parallel and then grounded; several AC electrodes on the installation plate are connected in parallel and then connected to the AC high-voltage power supply; connect. The device can significantly improve the flow control effect and achieve the purpose of turbulent flow drag reduction.

Description

A Drag Reduction Device Based on Negative Pressure Sliding Plasma Discharge

technical field

The invention belongs to the technical field of plasma discharge equipment, and in particular relates to a drag reducing device based on negative pressure sliding plasma discharge.

Background technique

With the rapid development of industry and economy in today's society, the demand for fossil energy is increasing, and carbon emissions are increasing rapidly. Therefore, improving the energy utilization rate of products has become a hot issue widely concerned by all walks of life. According to relevant research: during the flight of high subsonic aircraft, about 50% of the resistance comes from surface turbulent frictional resistance, and the increase of resistance will undoubtedly increase the fuel consumption. Among the operating costs of an aircraft, fuel costs account for about 30% of the total operating costs. Therefore, any reduction in surface frictional resistance can greatly save the energy consumption of the vehicle, improve the energy utilization rate of the product, and reduce the operating cost.

Studies have shown that turbulent frictional resistance is closely related to the flow vortex in the near-wall region. The commonly used drag reduction scheme is to destroy the self-sustaining process of the flow vortex and strip structure in the near-wall region, hinder the further development and evolution of the flow vortex, and affect the flow vortex. The effect of frictional resistance on the wall during the downsweeping process. Based on this control principle, many drag reduction methods have been developed. According to whether there is external energy input, it can be divided into passive control and active control. Traditional passive control methods (such as vortex generators, grooves, small ribs, etc.) have been fully researched and widely used, but have limited potential in improving the performance of aircraft, and it is difficult to obtain major breakthroughs. In addition, the control method of passive control is predetermined, and the control effect can only deal with one or several specific flow fields, which cannot achieve the best control effect in real application scenarios. Active flow control technology is to apply a certain degree of disturbance through external energy input and couple with the flow mode of the flow field on the surface of the object to achieve flow control. The advantage of active control is that it can change the local or global flow field at an appropriate time and position through local energy input, and then achieve the purpose of reducing turbulent frictional resistance.

The drag reduction control of turbulent boundary layer based on plasma actuator is one of many active control methods. It has been widely studied because of its simple structure, small additional load, no complicated mechanical structure, and fast response. At present, the most studied one is the dielectric barrier discharge plasma driver (DBD).

Although DBD has many advantages mentioned above, there are still some shortcomings such as small discharge area, low induction velocity, low energy efficiency ratio, and single direction of induced jet flow, which limit its further engineering application. In order to further improve and improve the performance of DBD, scholars from various countries have optimized the material of the dielectric layer and the excitation electrical parameters, among which there are many effective solutions, such as: negative pulse DC discharge plasma actuator and sliding discharge plasma actuator . Negative pulse DC discharge is to replace the original AC power supply with negative pulse DC power supply on the basis of traditional DBD, which can achieve very high instantaneous body force level under the condition of very small energy consumption. The sliding discharge is based on the two electrodes of the traditional DBD, and a DC high-voltage electrode is added on the other side of the exposed electrode, and the induced jet velocity is increased to a certain extent without significantly increasing the power consumption.

Contents of the invention

The purpose of the present invention is to provide a drag reduction device based on negative pressure sliding plasma discharge, which combines the advantages of sliding discharge plasma actuators and pulsed DC discharge plasma actuators, can significantly improve the flow control effect, and achieve turbulent flow reduction. blocking purpose.

The technical solution adopted in the present invention is a drag reduction device based on negative pressure sliding plasma discharge, which is mainly used for drag reduction of airfoils, including a mounting plate on which several gap-free arrays are arranged. The plasma discharge unit; the plasma discharge unit includes a regular hexagonal tubular dielectric layer, an AC electrode and a pulsed DC electrode are arranged along the inner wall surface of the regular hexagonal tubular dielectric layer, and the corresponding regular hexagonal tubular dielectric between the AC electrode and the pulsed DC electrode There are buried electrodes buried in the layer, and the buried electrodes, AC electrodes and pulsed DC electrodes are all in the shape of positive hexagonal tubes; several buried electrodes on the installation plate are connected in parallel and then grounded, and several AC electrodes on the installation plate are connected in parallel to the AC high-voltage power supply, and the installation plate Several pulsed DC electrodes are connected in parallel to the pulsed high-voltage DC power supply.

The present invention is also characterized in that,

The radius of the inscribed circle of the regular hexagonal tubular medium layer is 10mm, the thickness is 0.5-3mm, and the length is 40-70mm. The material is polytetrafluoroethylene; the material of the mounting plate is insulating material.

Buried electrodes, AC electrodes and pulsed DC electrodes are all copper electrodes.

The thickness of the buried electrode is 0.03mm-0.3mm, and the width is 20-50mm; the thickness of the AC electrode and the pulsed DC electrode are both 0.03mm-0.3mm, and the width is 5mm.

The AC high-voltage power supply voltage is 5Kv-15Kv, and the pulse high-voltage DC power supply voltage is 5Kv-10Kv.

The beneficial effects of the present invention are:

(1) A drag reducing device based on a negative pressure sliding plasma discharge of the present invention combines the advantages of a sliding discharge plasma actuator and a pulsed DC discharge plasma actuator, which can increase the instantaneous electromotive force of the discharge area and increase the field emission The number of electrons generated increases the kinetic energy carried by the electrons, producing more O ₃ ^-2 and O ₂ ^-2 , and at the same time O ₃ ^-2 and O ₂ ^-2 can also obtain more energy from the electric field, and finally produce a larger Induced air flow rate.

(2) A drag reducing device based on negative pressure sliding plasma discharge of the present invention, under the same voltage, can generate a stronger electric field on the surface of the induced flow field compared with a common DBD, and can generate Larger body force, with higher energy efficiency.

(3) The present invention is a drag reducing device based on negative pressure sliding plasma discharge. The special positive hexagonal tube configuration has good adaptability, can make the most use of the flow field surface, and can be flexibly selected according to actual use requirements layout.

(4) A drag reduction device based on negative pressure sliding plasma discharge of the present invention can generate greater induced air flow velocity and instantaneous body force, increase the lifting effect and smashing efficiency of the flow direction vortex, thereby increasing the effective drag reduction The flow direction area of the region reduces turbulent flow resistance.

(5) A drag reduction device based on a negative pressure sliding plasma discharge of the present invention is triggered by an electrical signal and has a fast response speed. It can cooperate with a closed-loop control system to adjust the power supply in real time according to the state of the surface flow field, thereby increasing the drag reduction efficiency , reduce energy loss.

(6) The induced air flow of the drag reducing device based on negative pressure sliding plasma discharge of the present invention is ejected from the surface of the AC electrode, and negative pressure will be formed in the tube, forcing the rear air to flow into the positive hexagonal tube, thereby increasing the air volume.

Description of drawings

Fig. 1 is a schematic structural view of a plasma discharge unit in a drag reducing device based on negative pressure sliding plasma discharge of the present invention;

Fig. 2 is a front view of the plasma discharge unit in a drag reducing device based on negative pressure sliding plasma discharge of the present invention;

Fig. 3 is a schematic diagram of the induced jet flow direction of the plasma discharge unit in a drag reducing device based on negative pressure sliding plasma discharge of the present invention;

Fig. 4 is a partial enlarged view of place C in Fig. 3;

Fig. 5 is a structural schematic diagram of a drag reducing device based on negative pressure sliding plasma discharge of the present invention;

Fig. 6 is a schematic diagram of the surface flow field when the drag reducing device based on the negative pressure sliding plasma discharge of the present invention is not opened;

Fig. 7 is a schematic diagram of the surface flow field after the drag reducing device based on the negative pressure sliding plasma discharge of the present invention is turned on.

In the figure, 1. regular hexagonal tubular dielectric layer, 2. buried electrode, 3. alternating current electrode, 4. pulsed direct current electrode, 5. installation plate.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

A drag reduction device based on negative pressure sliding plasma discharge of the present invention, as shown in Figure 1-7, includes a mounting plate 5, and a plurality of plasma discharge units arranged in an array without gaps are installed on the mounting plate 5 When in use, the plasma discharge unit is arranged perpendicular to the surface of the plate; the plasma discharge unit includes a regular hexagonal tubular dielectric layer 1, and an AC electrode 3 and a pulsed DC electrode 4 are arranged along the inner wall surface of the regular hexagonal tubular dielectric layer 1, and the AC electrode The regular hexagonal tubular dielectric layer 1 between 3 and the pulsed direct current electrode 4 is embedded with a buried electrode 2, and the buried electrode 2, the alternating current electrode 3 and the pulsed direct current electrode 4 are all regular hexagonal tubular; the buried electrode 2, the alternating current electrode 3 and the The projection of the pulsed DC electrode 4 on the axial plane of the regular hexagonal tubular dielectric layer 1 is seamlessly connected, and the distance between the AC electrode 3 and the pulsed DC electrode 4 is equal to the width of the buried electrode 2; several buried electrodes 2 are installed on the flat plate 5 After parallel connection, grounding, several AC electrodes 3 on the installation plate 5 are connected in parallel to the AC high-voltage power supply, and several pulsed DC electrodes 4 on the installation plate 5 are connected in parallel to the pulse high-voltage DC power supply, and the AC electrodes 3 are arranged in the preset flow field. In the upstream section, the pulsed DC electrode 4 is arranged in the downstream section of the preset flow field.

The inscribed circle radius of the regular hexagonal tubular dielectric layer 1 is 10mm, the thickness is 0.5-3mm, and the length is 40-70mm, and the material is polytetrafluoroethylene; the material of the mounting plate 5 is insulating material.

The buried electrode 2, the AC electrode 3 and the pulsed DC electrode 4 are all copper electrodes.

The thickness of the buried electrode 2 is 0.03mm-0.3mm, and the width is 20-50mm; the thickness of the AC electrode 3 and the pulsed DC electrode 4 are both 0.03mm-0.3mm, and the width is 5mm.

The AC high-voltage power supply voltage is 5Kv-15Kv, and the pulse high-voltage DC power supply voltage is 5Kv-10Kv. Studies have shown that based on the drag reduction principle described in the background art, the key to increasing the drag reduction effect is to increase the induced jet velocity and instantaneous body force generated by the plasma actuator. The dielectric constant of the medium layer and the surface electric field strength of the flow field are the two main factors that limit the induced jet velocity and volume force generated by ordinary DBD. The dielectric constant is limited by the material, and it is difficult to make a major breakthrough. The gap between the AC electrode and the pulsed DC electrode on the inner surface of the plasma discharge unit of the device can generate a stronger instantaneous electric field on the surface of the flow field, and a stronger instantaneous electric field can generate a stronger instantaneous body force, and a larger instantaneous body force can While enhancing the velocity of the induced jet, the efficiency of breaking up the flow direction vortex is improved. The improvement of the crushing efficiency of the flow direction vortex can also reduce the energy consumption of the drag reduction device and improve the drag reduction efficiency.

Subsequently, our research group found through experiments that the positive pulse DC power supply can also produce a certain drag reduction effect. The sliding discharge is based on the two electrodes of the traditional DBD, and a DC high-voltage electrode is added, which increases the discharge area and can also achieve the deflection of the induced jet direction.

Driven by an AC high-voltage power supply and a pulsed high-voltage DC power supply, the device can generate jets perpendicular to the object surface, lift the flow vortex and break the flow vortex, thereby increasing the flow area of the effective drag reduction area. The number and arrangement of the plasma discharge units can be flexibly selected according to actual needs, and the parameters can be adjusted in real time according to the change of the flow field in the near-wall area to realize the drag reduction control of the active turbulent boundary layer.

The buried electrode 2 is grounded, the AC electrode 3 and the pulsed DC electrode 4 are respectively connected to the AC high-voltage power supply and the pulsed high-voltage DC power supply. After the power is turned on, the surface of the AC electrode 3 can generate a jet along the tube wall, and the surface of the positive hexagonal lumen forms a negative pressure , to force the rear air to flow into the regular hexagonal tubular medium layer 1, as shown in Figure 3, a converging airflow is finally formed, and the blowing intensity can be adjusted by adjusting the power of the power supply. The actuator array is arranged on a flat plate without gaps The above constitutes a drag reduction device based on negative pressure sliding plasma discharge.

Figure 6 shows that the device is not turned on, and there are many large flow vortices in the flow field; Figure 7 shows that after the device is turned on, a jet flow perpendicular to the object surface is generated above the installation plate, and the flow vortices above the installation plate are obviously lifted and broken .

The device has the following advantages: First, the configuration of the negative pressure sliding discharge plasma actuator is proposed, which can further improve the induced jet velocity and energy efficiency ratio of the plasma actuator, and promote the engineering application of plasma turbulence drag reduction control. The second is the special hexagonal tube configuration, with flexible arrangement and strong adaptability. It can be arranged on surfaces of various shapes according to actual needs. Compared with the arrangement of ordinary round-hole jet arrays, this device can maximize the use of the surface of the flow field. The third is that the plasma discharge unit has no mechanical parts and has a small additional load. It is triggered by electrical signals, has high reliability and fast response speed. The intensity of the induced airflow can be adjusted in real time by adjusting the power of the power supply according to the state of the surface flow field. The fourth is the negative pressure sliding discharge plasma actuator, which can generate higher instantaneous body force, increase the efficiency of lifting and breaking up the flow direction vortex, and improve the effect of turbulent flow drag reduction. Fifth, the device is designed to reduce energy consumption and operating costs, and is a green and low-carbon technology.

Claims (5)

1. The drag reduction device based on negative pressure type sliding plasma discharge is characterized by comprising an installation flat plate (5), wherein a plurality of plasma discharge units which are arrayed in a gapless manner are installed on the installation flat plate (5); the plasma discharge unit comprises a regular hexagonal tubular dielectric layer (1), an alternating current electrode (3) and a pulse direct current electrode (4) are arranged along the surface of the inner wall of the regular hexagonal tubular dielectric layer (1), a buried electrode (2) is embedded in the regular hexagonal tubular dielectric layer (1) corresponding to the position between the alternating current electrode (3) and the pulse direct current electrode (4), and the buried electrode (2), the alternating current electrode (3) and the pulse direct current electrode (4) are all in a regular hexagonal tubular shape; a plurality of buried electrodes (2) on the installation flat plate (5) are connected in parallel and then grounded, a plurality of alternating current electrodes (3) on the installation flat plate (5) are connected in parallel and then connected with an alternating current high-voltage power supply, and a plurality of pulse direct current electrodes (4) on the installation flat plate (5) are connected in parallel and then connected with a pulse high-voltage direct current power supply; the alternating current electrode (3) is arranged at the upstream section of the preset flow field, and the pulse direct current electrode (4) is arranged at the downstream section of the preset flow field.

2. The drag reduction device based on negative pressure type sliding plasma discharge according to claim 1, wherein the radius of an inscribed circle of the regular hexagonal tubular medium layer (1) is 10mm, the thickness is 0.5-3mm, the length is 40-70mm, and the material is polytetrafluoroethylene; the installation flat plate (5) is made of an insulating material.

3. The drag reduction device based on negative pressure type sliding plasma discharge according to claim 1, wherein the buried electrode (2), the alternating current electrode (3) and the pulse direct current electrode (4) are all copper electrodes.

4. The drag reduction device based on negative pressure type sliding plasma discharge according to claim 1, wherein the thickness of the buried electrode (2) is 0.03mm to 0.3mm, and the width is 20 mm to 50mm; the thickness of the alternating current electrode (3) and the thickness of the pulse direct current electrode (4) are both 0.03mm-0.3mm, and the width of the alternating current electrode and the width of the pulse direct current electrode are both 5mm.

5. The drag reduction device based on negative pressure type sliding plasma discharge according to claim 1, wherein the alternating current high voltage power supply voltage is 5Kv-15Kv, and the pulse high voltage direct current power supply voltage is 5Kv-10Kv.

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