Turbulence friction resistance reduction device and method based on array type corona discharge

Abstract

The turbulence friction resistance reduction device based on array type corona micro-blowing comprises a corona discharge cavity plate (1) and a discharge electrode (2). A plurality of cylindrical inclined micro holes are formed in the front face of the corona discharge cavity plate (1) and serve as corona discharge anodes, the cylindrical inclined micro holes are distributed in the front face of the corona discharge cavity plate (1) in an array mode, and the inclined directions of the cylindrical inclined micro holes are changed in a staggered mode. The high-voltage direct-current power supply (4) generates direct-current high voltage and applies the direct-current high voltage to the discharge electrode (2), plasma (6) is generated between the discharge electrode (2) and the corona discharge cavity plate (1), two oblique jet flows of each discharge group are coupled to form spirally-rising jet flows, a normal blowing effect is generated in a flow field, and turbulent friction resistance reduction is achieved. The invention further provides a turbulence friction resistance reduction device and method based on array type corona discharge. The sensor is arranged in a flow field to collect flow field data, the flow field state is sensed in real time, the corona discharge mode is controlled, the optimal resistance reduction effect is kept in the rapidly-changed flow field state, and the resistance reduction adaptability is further improved.

Description

Technical Field

[0001] The present invention relates to the field of plasma flow control technology, in particular to a novel plasma actuator for turbulent boundary layer friction drag reduction, and specifically to a turbulent friction drag reduction device and method based on array corona discharge. Background Art

[0002] In the field of aerodynamics, drag reduction has always been the pursuit of aircraft aerodynamic design. When an aircraft cruises at subsonic speeds, about half of the drag comes from wall friction resistance. Therefore, friction resistance is directly related to fuel consumption. In the civil aviation industry, after calculation, 30% to 40% of the ticket price is used to pay for fuel costs. Reducing aircraft turbulent friction resistance can significantly increase aircraft range and flight time, reduce environmental pollution and fuel consumption, and reduce flight costs, which is beneficial to improving aircraft flight performance and economic efficiency.

[0003] In order to achieve aircraft friction drag reduction, people have developed a variety of flow control methods, which are mainly divided into passive control and active control. The typical passive flow control method is mainly based on grooves. Grooves refer to flow-direction protrusions arranged periodically along the span direction on the wall. By separating the underlying strip structure of the turbulent boundary layer, it can achieve a drag reduction effect of about 8% to 10%, but its adaptability is poor and its working range is limited. Most grooves can only achieve optimal drag reduction within a very small Reynolds number range. Once the design Reynolds number is deviated due to flight speed, altitude or weather changes, the drag reduction effect will drop significantly, and even increase drag. In addition, its disturbance effect is limited. When the incoming flow velocity increases, the fixed groove spacing cannot match the dense turbulent strip structure spacing, and it is difficult to effectively intervene in the turbulent boundary layer, thus losing the drag reduction effect. The above changes are inevitable in actual flight, which makes it difficult for simple grooves to achieve drag reduction applications in actual flight.

[0004] Typical active flow control methods include air blowing and spanwise wall oscillation, which have strong adaptability. The air blowing method can achieve a 20% to 30% turbulent drag reduction effect, while the spanwise wall oscillation can reduce the turbulent friction resistance by 45%. However, active control methods often require complex air bleed pipes, air sources, motors, and complex mechanical structures. At the same time, traditional air blowing methods require air to be drawn from the engine, which damages engine performance. The energy and cost consumed by driving air blowing and spanwise wall oscillation exceed the drag reduction benefits they bring, making them impossible to be used in practice.

[0005] Plasma turbulence drag reduction method is a new type of active drag reduction method with the advantages of simple structure and low drag reduction cost. It is the most practical turbulence drag reduction method and has become a research hotspot in recent years. Among the plasma turbulence drag reduction methods, dielectric barrier discharge is commonly used, which can achieve an 11% airfoil turbulence friction drag reduction effect at an incoming flow velocity of 20m / s. However, due to the very limited intensity of dielectric barrier discharge (the induced velocity is generally only 2-3m / s), when the incoming flow velocity increases to 30m / s, the drag reduction effect rapidly drops to 2.6%; when the incoming flow velocity increases further, the drag reduction effect disappears, and 90% of the dielectric barrier discharge is a thermal effect, with low mechanical efficiency, making it difficult to achieve practical application. Therefore, it is urgent to seek a more efficient and flexible plasma turbulence drag reduction method to achieve efficient drag reduction at higher incoming flow velocities.

[0006] A large number of studies have shown that in a turbulent boundary layer, using microporous materials to generate normal micro-blowing on the wall can significantly reduce the velocity and velocity pulsation at the bottom of the boundary layer, forming a low-speed zone and a low-pulsation zone at the bottom of the boundary layer, thereby effectively reducing turbulent friction resistance at a higher incoming flow velocity. However, the generation of the above-mentioned micro-blowing generally requires complex pipelines to lead high-pressure gas from the inside of the aircraft engine, which not only imposes a serious structural and weight burden on the aircraft, but also damages the engine performance, making it difficult for the gains from drag reduction to offset the losses caused by it, and difficult to achieve practical application. Summary of the invention

[0007] In view of the shortcomings of the prior art, the present invention provides a turbulent friction drag reduction device based on array corona discharge, comprising a corona discharge cavity plate 1 and an electrode 2, wherein:

[0008] The corona discharge cavity plate 1 is in the shape of a thin rectangular parallelepiped; a plurality of cylindrical oblique micropores are opened on the front of the corona discharge cavity plate 1 as the anode of the corona discharge, and these cylindrical oblique micropores are distributed in an array on the front of the corona discharge cavity plate 1, and the inclination direction and inclination angle of the cylindrical oblique micropores in the same row are the same, and their axes are parallel to each other and in the same horizontal vertical plane perpendicular to the front of the corona discharge cavity plate 1; the inclination angle of the cylindrical oblique micropores in the next row is the same as the inclination angle of the previous row, and the inclination direction of the cylindrical oblique micropores in the next row is the same as that of the previous row. The inclination direction is symmetrical about the longitudinal vertical plane perpendicular to the front face of the corona discharge cavity plate 1; when there are multiple rows of cylindrical oblique micropores, the inclination direction of the cylindrical oblique micropores is staggered according to the above situation; the number of rows of cylindrical oblique micropores is an even number; viewed from the front face of the corona discharge cavity plate 1, a column of cylindrical oblique micropores is N, N is an even number, and two are grouped from top to bottom, forming a total of N / 2 groups, and each group of cylindrical oblique micropores forms a pair of discharge electrode holes; the spacing between adjacent cylindrical oblique micropores between two groups is greater than the spacing between two adjacent cylindrical oblique micropores in each group;

[0009] A discharge electrode 2 is fixedly arranged under each cylindrical oblique micropore of the corona discharge cavity plate 1; there is a space between the discharge electrode 2 and the corona discharge cavity plate 1; the discharge electrode 2 is coaxial with the lower surface circle of the cylindrical oblique micropore; two adjacent discharge electrodes 2 with different oblique hole directions form a corona discharge group, each corona discharge group is connected in parallel or works independently, and each corona discharge group is independently controlled.

[0010] In one embodiment of the present invention, the thickness of the corona discharge cavity plate 1 is 1 to 5 mm; the diameter of each oblique micropore on the corona discharge cavity plate 1 is 1 to 5 mm; the distance between each group of two adjacent cylindrical oblique micropores on the corona discharge cavity plate 1 is 1 to 2 mm; the distance between two groups of adjacent cylindrical oblique micropores is 2 to 3 mm; in the horizontal direction, the distance between the center of the first and last cylindrical hole and the edge of the corona discharge cavity plate 1 is 3 to 5 mm; in the longitudinal direction, the distance between the center of the first and last cylindrical hole and the edge of the corona discharge cavity plate 1 is 3 to 5 mm;

[0011] The discharge electrode 2 has a diameter of 1 to 3 mm and a height of 1 to 3 mm; the distance between each electrode and the corresponding cylindrical micropore on the corona discharge cavity plate is 1 to 3 mm.

[0012] In a specific embodiment of the present invention, the corona discharge cavity plate 1 is made of copper, with a length of 27 mm, a width of 29 mm, and a thickness of 3 mm. The diameter of each oblique micropore on the corona discharge cavity plate 1 is 3 mm. The distance between each group of two adjacent cylindrical oblique micropores on the corona discharge cavity plate 1 is 1 mm. The distance between the adjacent cylindrical oblique micropores between the two groups is 2 mm. There are 30 cylindrical oblique micropores and 15 discharge groups. In the horizontal direction, the distance between the center of the first and last cylindrical holes and the edge of the corona discharge cavity plate 1 is 3.5 mm. In the longitudinal direction, the distance between the center of the first and last cylindrical holes and the edge of the corona discharge cavity plate 1 is 3.5 mm.

[0013] The discharge electrode 2 is a solid cylinder made of copper, with a diameter of 1 mm and a height of 2 mm; the distance between each electrode and the cylindrical microhole on the corresponding corona discharge cavity plate is 2 mm.

[0014] In another embodiment of the present invention, the device is electrically connected as follows: a high-voltage DC power supply 4 generates a DC high voltage, one output end of which is connected to the corona discharge cavity plate 1 , and the other end is connected to the discharge electrode 2 .

[0015] In another specific embodiment of the present invention, the high-voltage DC power supply 4 is a high-voltage DC power supply with a voltage > 8 kV.

[0016] In another embodiment of the present invention, the device is embedded in the surface where drag reduction is required, the front side of the corona discharge cavity plate 1 is flush with the surface where drag reduction is required, and the device is arranged at a position slightly upstream in the drag reduction area.

[0017] In addition, in one embodiment of the present invention, the circuit of the device is connected to the controller 3, and a plurality of small relays are arranged inside the entire circuit to respectively control the voltage polarity on the electrodes of each corona discharge electrode group 5; a plurality of small transformers are arranged to respectively control the DC voltage on each corona discharge cavity plate 1 and the corona discharge electrode 2; and sensors are arranged in the flow field to collect flow field data.

[0018] The working method of the above-mentioned turbulent friction drag reduction device based on array corona discharge is as follows:

[0019] For a single corona discharge group, the high-voltage DC power supply 4 generates a DC high voltage, which is applied to the discharge electrode 2, and a strong electric field is generated between the discharge electrode 2 and the corona discharge cavity plate 1. The electric field strength exceeds the critical value, so that the air molecules collide and ionize to generate a self-sustaining discharge, generate plasma 6, and form an ion wind. The two oblique jets of each discharge group are coupled to form a spiral rising jet, which produces a normal blowing effect in the flow field;

[0020] The high-voltage DC power supply 4 is turned on to ionize the air to generate plasma 6 to form ion wind. The two oblique jets of each discharge group are coupled to form a spirally rising normal jet, which causes the bottom fluid of the boundary layer to wash upward and realize turbulent friction drag reduction.

[0021] A turbulent friction drag reduction method based on array corona discharge, which is based on the above-mentioned turbulent friction drag reduction device based on array corona discharge, and the device works in the following three modes:

[0022] Mode 1: When a high-voltage DC power supply 4 is connected, the corona discharge cavity plate 1 is the cathode, and the discharge electrode 2 is the anode, plasma 6 is generated between the corona discharge cavity plate 1 and the discharge electrode 2, forming a blowing effect, and plasma jets are generated from the two inclined holes of each group to couple to form a spiral rising normal vortex blowing;

[0023] Mode 2: When a high-voltage sinusoidal power supply is connected, the corona discharge cavity plate 1 is the cathode and the discharge electrode 2 is the anode, plasma 6 is generated between the corona discharge cavity plate 1 and the discharge electrode 2, forming a blowing effect. The plasma jets generated from the two inclined holes of each group are coupled to form a spiral rising normal vortex blowing. The blowing intensity of each group of electrodes changes sinusoidally with the voltage.

[0024] Mode 3: When a high-voltage DC power supply 4 is connected, the corona discharge cavity plate 1 is the anode, and the discharge electrode is the cathode, plasma 6 is generated between the corona discharge cavity plate 1 and the discharge electrode 2, forming an air suction effect;

[0025] The method is specifically as follows:

[0026] Step S1, the sensor collects flow field data, arranges the sensor in the flow field, collects the temperature, pressure, velocity, wall shear stress and other information in the flow field in real time, and inputs the data into the controller;

[0027] Step S2, the controller control circuit selects one of the above three working modes, tries the above three working modes in turn and adjusts the voltage of each corona discharge group, the discharge density of the array corona discharge group and other parameters;

[0028] Step S3, the sensor collects flow field data again to collect flow field information after corona discharge;

[0029] Step S4, analyzing the data collected by the sensor in the controller, comparing the information before and after the corona discharge, and comparing the changes in the friction resistance measured before and after the corona discharge under the temperature, pressure, and speed conditions. If the measured friction resistance is less than the friction resistance before the corona discharge, the expected drag reduction effect is achieved. Otherwise, return to step S2 and select a new working mode or a new discharge state according to the flow field information; compare the drag reduction effects of different modes to select the optimal drag reduction mode, and the selection method is as follows: when the aircraft is flying at high speed, it is necessary to increase the voltage and increase the density of the corona discharge group to form a thicker air film in the drag reduction arrangement area, effectively reduce the viscous resistance between the air and the wall, and meet the high-speed drag reduction requirements; when flying at low speed, a lower voltage and opening of some corona discharge electrode groups can form an air film of a certain thickness in the drag reduction arrangement area, thereby achieving the drag reduction requirements and saving energy.

[0030] In one embodiment of the present invention, a surface shear stress sensor is used to measure the surface friction resistance.

[0031] The present invention utilizes corona discharge which is more efficient than dielectric barrier discharge to generate plasma micro-blowing in the flow field, thereby realizing turbulent friction drag reduction at a higher incoming flow velocity.

[0032] The electrode structure required for corona discharge is simple and lightweight, which effectively reduces the weight and complexity of the system and improves the drag reduction effect. In addition, the adjacent blowing channels in the present invention can couple with each other to generate normal vortices, so that the low-speed area and low-pulsation area generated by the microjets are conducted to higher places in the boundary layer, and effective drag reduction can be achieved at a higher incoming flow rate with a smaller flow rate. The corona array turbulent friction drag reduction device has higher mechanical efficiency and can effectively generate normal jets to achieve turbulent drag reduction. The present invention belongs to an active method with stronger adaptability. It can adjust the discharge intensity and density in real time according to the incoming flow conditions to meet the drag reduction needs under different incoming flow conditions. It can also achieve effective drag reduction in actual flight where the incoming flow conditions change rapidly. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1The overall structural schematic diagram of the turbulent friction drag reduction device based on array-type corona micro-blowing is shown;

[0034] Figure 2 A diagram showing the electrode geometry;

[0035] Figure 3 A corona discharge chamber plate geometry diagram is shown;

[0036] Figure 4 A schematic diagram of the oblique micro-hole grouping of a turbulent friction drag reduction device based on array-type corona micro-blowing is shown;

[0037] Figure 5 The schematic diagram of the working of the turbulent friction drag reduction device based on array-type corona micro-blowing is shown;

[0038] Figure 6 A schematic diagram showing the installation position of a turbulent friction drag reduction device based on array-type corona micro-blowing is shown;

[0039] Figure 7 Showing the circuit diagram of the device of the present invention;

[0040] Figure 8 A schematic diagram showing the operation of a turbulent friction drag reduction device based on array-type corona micro-blowing when each group of DC voltages is the same;

[0041] Fig. 9 The schematic diagram of the operation of the turbulent friction drag reduction device based on array-type corona micro-blowing when each group of DC high voltage is modulated is shown; the circuit diagram of the device of the present invention is shown;

[0042] Fig.10 The schematic diagram of the operation of the turbulent friction drag reduction device based on array-type corona micro-blowing is shown when the corona discharge cavity plate is connected to the cathode and the electrode is connected to the anode;

[0043] Fig.11 A flow chart of a turbulent friction drag reduction method based on array-type corona micro-blowing is shown;

[0044] Fig.12 A diagram showing the relationship between the various parts of the turbulent friction drag reduction method based on array corona micro-blowing is shown.

[0045] Notes on the attached drawings:

[0046] 1 corona discharge cavity plate 2 electrode 3 controller 4 high voltage DC power supply 5 corona discharge group 6 plasma 1), 2), 3), 4), 5) first, second, third, fourth, fifth corona discharge group DETAILED DESCRIPTION

[0047] The present invention provides an array-type corona discharge turbulent friction drag reduction device, comprising a corona discharge cavity plate 1, an electrode 2, such as Figure 1 shown.

[0048] like Figure 3 As shown, the corona discharge cavity plate 1 is in the shape of a thin rectangular parallelepiped and is made of conductive metals such as copper, silver, and tungsten. A plurality of cylindrical oblique micropores are opened on the front of the corona discharge cavity plate 1, which serve as the anode of the corona discharge and the discharge electrode 2 to generate plasma. These cylindrical oblique micropores are distributed in an array on the front of the corona discharge cavity plate 1. The inclination direction and inclination angle of the cylindrical oblique micropores in the same row are the same, and their axes are parallel to each other and in the same horizontal vertical plane perpendicular to the front of the corona discharge cavity plate 1; the inclination angle of the cylindrical oblique micropores in the next row is the same as the inclination angle of the previous row, and the inclination direction of the cylindrical oblique micropores in the next row is symmetrical with the inclination direction of the previous row about the longitudinal vertical plane perpendicular to the front of the corona discharge cavity plate 1; when there are multiple rows of cylindrical oblique micropores (must be an even number of rows), the inclination direction of the cylindrical oblique micropores is staggered and changed according to the above situation, and no further description is given. Viewed from the front of the corona discharge cavity plate 1 , a row of cylindrical oblique micropores must be an even number, for example N, and two are grouped together from top to bottom, forming a total of N / 2 groups, and each group of cylindrical oblique micropores forms a pair of discharge electrode holes.

[0049] The discharge electrode 2 is a solid needle, and a discharge electrode 2 is fixedly arranged under each cylindrical oblique microhole of the corona discharge cavity plate 1. There is a space between the discharge electrode 2 and the corona discharge cavity plate 1, and plasma 6 is generated between the discharge electrode 2 and the corona discharge cavity plate 1. Figure 2 As shown. The discharge electrode 2 is coaxial with the lower surface of the cylindrical oblique micropore. The discharge electrode 2 is usually made of copper or tungsten. Two adjacent discharge electrodes 2 with different oblique hole directions (shown in the figure as the upper and lower discharge electrodes 2) form a corona discharge group, such as Figure 4 As shown, each corona discharge group is connected in parallel or works independently, and each corona discharge group can be controlled independently.

[0050] The high-voltage DC power supply 4 is used to generate a DC high voltage to drive the electrode array to discharge, and one end of the output is connected to the corona discharge cavity plate 1, and the other end is connected to the discharge electrode 2. When the high-voltage DC power supply 4 is turned on, the air between the corona discharge cavity plate 1 and the discharge electrode 2 will be ionized to generate plasma 6.

[0051] In a specific embodiment of the present invention, the corona discharge cavity plate 1 is made of copper, and its length ( Figure 4 The horizontal direction is the length direction) is 27mm; the width ( Figure 4The longitudinal direction is the width direction) is 29mm; the thickness can be 1-5mm, preferably 3mm, and 3mm is taken in this example. The diameter of each oblique micropore on the corona discharge cavity plate 1 can be 1-5mm, preferably 3mm, and 3mm is taken in this example. The distance between each group of two adjacent cylindrical oblique micropores on the corona discharge cavity plate 1 can be 1-2mm, preferably 1mm, and 1mm in this example. The distance between adjacent cylindrical oblique micropores between two groups can be 2-3mm, preferably 2mm, and 2mm in this example. The distance between adjacent cylindrical oblique micropores between two groups must be greater than the distance between two adjacent cylindrical oblique micropores in each group; there are 30 cylindrical oblique micropores and 15 discharge groups. Figure 4 As shown. In the transverse direction, the distance between the center of the first and last cylindrical hole and the edge of the corona discharge cavity plate 1 can be 3-5 mm, preferably 3.5 mm, and 3.5 mm in this example. In the longitudinal direction, the distance between the center of the first and last cylindrical hole and the edge of the corona discharge cavity plate 1 can be 3-5 mm, preferably 3.5 mm, and 3.5 mm in this example.

[0052] The discharge electrode 2 is made of copper, and its diameter can be 1-3mm, and in this example, it is 1mm, and its height can be 1-3mm, and in this example, it is a 2mm cylinder. Each electrode corresponds to a cylindrical microhole on the corona discharge cavity plate, and is coaxial with the lower surface circle of the oblique microhole, and the distance is 1-3mm, and in this example, it is 2mm.

[0053] The high-voltage DC power supply 4 can select any high-voltage DC power supply with a voltage > 8kV. The volume and weight of the power supply should be as small as possible to reduce the structural weight cost of the device and adapt to application scenarios with limited space and load, such as drones.

[0054] First, the working process of a single corona discharge group, that is, the discharge electrodes 2 that are adjacent and have different oblique hole directions, after being energized is explained, which is specifically as follows: the high-voltage DC power supply 4 generates a DC high voltage, which is applied to the discharge electrode 2, and a strong electric field is generated between the discharge electrode 2 and the corona discharge cavity plate 1. The electric field strength exceeds the critical value, causing the air molecules to collide and free to cause self-sustaining discharge, generate plasma 6, and form ion wind. The two oblique jets of each discharge group are coupled to form a spiral rising jet, which produces a normal blowing effect in the flow field.

[0055] The discharge electrodes 2 are fixed correspondingly under the oblique micropores of the corona discharge cavity plate 1 to form an array arrangement, thereby forming an array type corona discharge turbulent friction drag reduction device. Connecting a high voltage DC power supply 4 ionizes the air to generate plasma 6 to form an ion wind, such as Figure 5 As shown, the two oblique jets of each discharge group are coupled to form a spirally rising normal jet, which causes the bottom fluid of the boundary layer to wash upward and achieve turbulent friction drag reduction.

[0056] The array-type corona discharge turbulent friction drag reduction device of the present invention is embedded into the surface that needs drag reduction, and the front side of the corona discharge cavity plate 1 is flush with the surface that needs drag reduction, such as Figure 6 As shown. Since the drag reduction effect can continue to exist for a distance after leaving the device in the flow field, in the specific arrangement, the device of the present invention can be arranged at a position slightly upstream of the drag reduction area to save discharge energy and improve drag reduction efficiency;

[0057] In the specific implementation process, the circuit diagram is as follows Figure 7 As shown, the circuit of the turbulent friction drag reduction device of the array corona discharge of the present invention is connected to the controller 3, and a plurality of small relays are arranged inside the whole circuit, which can respectively control the voltage polarity on the electrodes of each corona discharge electrode group 5, wherein 1), 2), 3), 4), 5) the first, second, third, fourth, and fifth corona discharge groups are specific examples of the corona discharge electrode group 5; at the same time, a plurality of small transformers are arranged, which can respectively control the DC voltage on each electrode (corona discharge cavity plate 1 and corona discharge electrode 2). The sensor is arranged in the flow field to collect flow field data, and the temperature, pressure, velocity, wall shear stress and other information in the flow field are collected in real time, and the data is input into the controller 3. The data collected by the sensor is analyzed in the controller 3, and the appropriate working mode and parameters are selected by the control circuit accordingly to realize a complex control strategy. Therefore, in practical applications, the present invention provides a variety of working modes, which can match the artificial intelligence algorithm to achieve a more significant control effect.

[0058] Mode 1: When a high voltage DC power supply 4 is connected, the corona discharge cavity plate 1 is the cathode, and the discharge electrode 2 is the anode, plasma 6 is generated between the corona discharge cavity plate 1 and the discharge electrode 2, forming a blowing effect, and plasma jets are generated from the two inclined holes of each group to couple to form a spiral rising normal vortex blowing, such as Figure 8 As shown (the bar graph in the figure is the voltage corresponding to each discharge group).

[0059] Mode 2: When a high voltage sinusoidal power supply is connected, the corona discharge cavity plate 1 is the cathode and the discharge electrode 2 is the anode, plasma 6 is generated between the corona discharge cavity plate 1 and the discharge electrode 2, forming a blowing effect. The plasma jets generated from the two inclined holes of each group are coupled to form a spiral rising normal vortex blowing. The blowing intensity of each group of electrodes changes sinusoidally with the voltage as shown in Fig. 9 As shown (the bar graph in the figure is the voltage corresponding to each discharge group).

[0060] Mode 3: When a high voltage DC power supply 4 is connected, the corona discharge cavity plate 1 is the anode and the discharge electrode is the cathode, plasma 6 is generated between the corona discharge cavity plate 1 and the discharge electrode 2, forming an air inhalation effect. Fig.10 As shown (the bar graph in the figure is the voltage corresponding to each discharge group).

[0061] Based on the above device, the present invention also proposes a turbulent friction drag reduction method based on array-type corona micro-blowing, the process of which is as follows: Fig.11 shown.

[0062] Step S1, the sensor collects flow field data. The sensor is arranged in the flow field to collect information such as temperature, pressure, velocity, wall shear stress, etc. in the flow field in real time, and inputs the data into the controller.

[0063] Step S2, the controller controls the circuit to select one of the three working modes, and tries the three working modes in sequence and adjusts the voltage of each corona discharge group, the discharge density of the array corona discharge group and other parameters.

[0064] Step S3: The sensor collects flow field data again to collect flow field information after corona discharge.

[0065] Step S4, analyze the data collected by the sensor in the controller, compare the information before and after the corona discharge, and compare the changes in the friction resistance measured before and after the corona discharge under the temperature, pressure, and speed conditions. If the measured friction resistance is less than the friction resistance before the corona discharge, the expected drag reduction effect is achieved. Otherwise, return to step S2 and select a new working mode or a new discharge state according to the flow field information. Compare the drag reduction effects of different modes to select the optimal drag reduction mode. The selection method is: when the aircraft is flying at high speed, it is necessary to increase the voltage, increase the density of the corona discharge group (the number of corona discharge groups turned on), and form a thicker air film in the drag reduction arrangement area, which can effectively reduce the viscous resistance between the air and the wall to meet the high-speed drag reduction requirements. When flying at low speed, a certain thickness of air film can be formed in the drag reduction arrangement area by turning on part of the corona discharge electrode group at a lower voltage to achieve the drag reduction requirements and save energy.

[0066] In a specific embodiment of the present invention, a surface shear stress sensor such as a hot film sensor (publication number: CN111351609A) is used to measure the surface friction resistance, and the change in friction resistance measured before and after corona discharge is compared. If the measured friction resistance is less than the friction resistance before corona discharge, the expected drag reduction effect is achieved and the work is completed. Otherwise, a new working mode or a new discharge state is selected from step S2 again according to the flow field information until the expected drag reduction effect is achieved. A large number of studies have shown that in a turbulent boundary layer, micro-blowing in the normal direction of the wall can significantly reduce the velocity and velocity pulsation of the bottom layer of the boundary layer, forming a low-speed zone and a low-pulsation zone in the bottom layer of the boundary layer, thereby effectively reducing the turbulent friction resistance at a higher incoming flow velocity.

[0067] During the implementation of the turbulent friction drag reduction method based on array corona discharge, the relationship between the various parts of the method is as follows: Fig.12 shown.

[0068] The differences between the present invention and other technologies in the same field are as follows:

[0069] Among the existing technologies, most turbulent drag reduction methods are simple passive drag reduction methods based on grooves. In the technology of turbulent drag reduction using plasma discharge, the discharge methods used are mostly dielectric barrier discharge and arc discharge, and there is no technology using corona discharge for turbulent drag reduction. The array-type corona micro-blowing turbulent friction drag reduction device and method proposed in the present invention, each group of corona discharge generates plasma jets at the oblique micropores that couple to form a spirally rising normal vortex jet, the working range of the jet is wider, and a certain thickness of air film is formed in the drag reduction arrangement area to reduce the friction resistance between the air and the wall, thereby achieving efficient turbulent friction drag reduction.

[0070] Compared with other turbulent drag reduction methods, the present invention has the following advantages:

[0071] 1. The structure is simpler and the drag reduction cost is low. Compared with the air-inducing micro-blowing method, the array-type corona discharge turbulent friction drag reduction device and method proposed in the present invention has a high mechanical efficiency of corona discharge, and the coupled airflow can penetrate deeper into a higher position to reduce drag. It also has a simple structure and does not require air to be drawn from the engine and other parts. The airflow channel is shorter and does not damage the engine performance, which has significant advantages.

[0072] 2. The effective incoming flow velocity is higher and the efficiency is higher. Compared with the plasma turbulent drag reduction method based on dielectric barrier discharge, the array-type corona discharge turbulent friction drag reduction device and method proposed in the present invention adopts a higher corona discharge intensity, which can produce effective disturbances at a higher incoming flow velocity, thereby producing a wider effective drag reduction incoming flow velocity range, effectively solving the problems of low discharge intensity and extremely limited effective drag reduction velocity range in the existing plasma turbulent drag reduction technology based on dielectric barrier discharge, and has a stronger application prospect in the drag reduction applications of various aircraft.

[0073] 3. Rapid response and flexible control. Since the corona electrode of the present invention can be regulated by the power supply electrical signal, compared with other turbulent drag reduction devices such as traditional methods such as blowing and suction, oscillating wall, piezoelectric synthetic jet, etc., the corona plasma actuator of the present invention has the advantages of simple structure, high frequency response, and fast response speed. It can produce a discharge effect within microseconds and achieve a rapid response to the flow field. This rapid response capability enables the present invention to reach the optimal design state more quickly and achieve better drag reduction effects. It also makes it possible to combine the present invention with various intelligent control methods such as deep reinforcement learning.

[0074] 4. Stronger adaptability. Compared with the traditional passive groove drag reduction method, the array corona discharge turbulent friction drag reduction device and method proposed in the present invention is an active method. It can adjust the discharge intensity and density in real time and change the control mode to meet the needs of drag reduction according to the flow field changes in actual flight. It can effectively adapt to the rapidly changing flow field conditions in actual flight and always maintain the best drag reduction state. The adaptability and practicality have been qualitatively enhanced.

[0075] The principle of corona discharge can be used to ionize the air to form plasma. The charged particles in the plasma move under the action of the electric field and collide with air molecules, thereby accelerating the air. This phenomenon is also called "ion wind". The present invention uses the principle of corona discharge to generate ion wind, accelerates the air through corona discharge, and combines microporous materials to generate normal microjets, thereby reducing the friction resistance under turbulent conditions. Since the electrode structure required for corona discharge is very simple, the structural weight of the high-voltage package driving the corona discharge is also very small, and it can also draw air nearby on the surface of the wing or fuselage, so the use of corona discharge to generate microjets can achieve the function of micro-blowing drag reduction at a very small structural weight cost, effectively reducing the weight and complexity of the system, improving the drag reduction effect, and making it have practical application capabilities. In addition, unlike the typical micro-jet drag reduction method that uses normal parallel inclined holes, the adjacent blowing channels in the present invention are coupled with each other, thereby generating normal vortices. By utilizing this vortex structure, the low-speed and low-pulsation areas generated by the microjet can be conducted to higher places in the boundary layer, thereby enhancing its ability to resist high-speed incoming flow, thereby achieving effective drag reduction at a higher incoming flow velocity with a smaller flow rate.

[0076] Compared with the typical plasma turbulence drag reduction method based on dielectric barrier discharge (DBD), the corona array turbulence friction drag reduction device provided by the present invention has higher mechanical efficiency and is more flexible, and can achieve drag reduction at higher incoming flow speeds. At the same time, the typical DBD drag reduction method is a passive method, and while producing a drag reduction effect, it will inevitably form a drag increase zone, while the corona microjet generated by the present invention is active, and while achieving drag reduction, it is not limited by the drag increase effect. Compared with the invention patent "Multilayer Array Microporous Discharge Plasma Generator and Generator Method" (Publication No.: CN 113543442A), the patent is completely based on DBD, with low mechanical efficiency. At the same time, since it has no unidirectional electric field, it cannot produce an effective normal jet. The corona array turbulence friction drag reduction device provided by the present invention has higher mechanical efficiency, can effectively produce a normal jet, and thus achieve turbulent drag reduction. Compared with the typical air-inducing micro-blowing method, the present invention does not need to bleed air from the engine and other parts, the airflow channel is shorter, the structural weight of the device is greatly reduced, and at the same time, it does not damage the engine performance, and the drag reduction benefit is significantly improved. Compared with traditional passive control methods such as groove drag reduction, the present invention is an active method with stronger adaptability. It can adjust the discharge intensity and density in real time according to the incoming flow conditions to meet the drag reduction needs under different incoming flow conditions. It can also achieve effective drag reduction in actual flight where the incoming flow conditions change rapidly.

Claims

1. A turbulent friction drag reduction device based on array corona discharge, comprising a corona discharge cavity plate (1) and an electrode (2), characterized in that: The corona discharge cavity plate (1) is in the shape of a thin rectangular parallelepiped; a plurality of cylindrical oblique micropores are formed on the front of the corona discharge cavity plate (1) to serve as an anode for corona discharge; the cylindrical oblique micropores are distributed in an array on the front of the corona discharge cavity plate (1); the inclination direction and inclination angle of the cylindrical oblique micropores in the same row are the same; their axes are parallel to each other and are in the same transverse vertical plane perpendicular to the front of the corona discharge cavity plate (1); the inclination angle of the cylindrical oblique micropores in the next row is the same as the inclination angle of the previous row; the inclination direction of the cylindrical oblique micropores in the next row is symmetrical with the inclination direction of the previous row about a longitudinal vertical plane perpendicular to the front of the corona discharge cavity plate (1); when there are multiple rows of cylindrical oblique micropores, the inclination directions of the cylindrical oblique micropores are altered in an alternating manner according to the above situation; The number of rows of cylindrical oblique micropores is an even number; when viewed from the front of the corona discharge cavity plate (1), there are N cylindrical oblique micropores in a row, where N is an even number, and two cylindrical oblique micropores are arranged in a group from top to bottom, forming a total of N / 2 groups, and each group of cylindrical oblique micropores forms a pair of discharge electrode holes; the spacing between adjacent cylindrical oblique micropores in two groups is greater than the spacing between two adjacent cylindrical oblique micropores in each group; A discharge electrode (2) is fixedly arranged under each cylindrical oblique micropore of a corona discharge cavity plate (1); a space is provided between the discharge electrode (2) and the corona discharge cavity plate (1); the discharge electrode (2) and the lower surface circle of the cylindrical oblique micropore are coaxial; two adjacent discharge electrodes (2) with oblique pores in different directions form a corona discharge group, each corona discharge group is connected in parallel or works independently, and each corona discharge group is independently controlled.

2. The turbulent friction drag reduction device based on array corona discharge according to claim 1, characterized in that: The corona discharge cavity plate (1) has a thickness of 1 to 5 mm; the diameter of each oblique micropore on the corona discharge cavity plate (1) is 1 to 5 mm; the spacing between each group of two adjacent cylindrical oblique micropores on the corona discharge cavity plate (1) is 1 to 2 mm; the spacing between two groups of adjacent cylindrical oblique micropores is 2 to 3 mm; in the horizontal direction, the distance between the center of the first and last cylindrical hole and the edge of the corona discharge cavity plate (1) is 3 to 5 mm; in the vertical direction, the distance between the center of the first and last cylindrical hole and the edge of the corona discharge cavity plate (1) is 3 to 5 mm; The discharge electrode (2) has a diameter of 1 to 3 mm and a height of 1 to 3 mm; the distance between each electrode and the cylindrical microhole on the corresponding corona discharge cavity plate is 1 to 3 mm.

3. The turbulent friction drag reduction device based on array corona discharge according to claim 2, characterized in that: The corona discharge cavity plate (1) is made of copper, with a length of 27 mm, a width of 29 mm, and a thickness of 3 mm. The diameter of each oblique micropore on the corona discharge cavity plate (1) is 3 mm. The spacing between each group of two adjacent cylindrical oblique micropores on the corona discharge cavity plate (1) is 1 mm. The spacing between two groups of adjacent cylindrical oblique micropores is 2 mm. There are 30 cylindrical oblique micropores and 15 discharge groups. In the horizontal direction, the distance between the center of the first and last cylindrical hole and the edge of the corona discharge cavity plate (1) is 3.5 mm. In the vertical direction, the distance between the center of the first and last cylindrical hole and the edge of the corona discharge cavity plate (1) is 3.5 mm. The discharge electrode (2) is a solid cylinder made of copper, with a diameter of 1 mm and a height of 2 mm; the distance between each electrode and the cylindrical microhole on the corresponding corona discharge cavity plate is 2 mm.

4. The turbulent friction drag reduction device based on array corona discharge according to claim 1, characterized in that: The device is electrically connected as follows: a high-voltage DC power supply (4) generates a DC high voltage, one output end of which is connected to a corona discharge cavity plate (1) and the other end is connected to a discharge electrode (2).

5. The turbulent friction drag reduction device based on array corona discharge according to claim 1, characterized in that: The high voltage DC power supply (4) is a high voltage DC power supply with a voltage > 8 kV.

6. The turbulent friction drag reduction device based on array corona discharge according to any one of claims 1 to 5, characterized in that: The device is embedded inside the surface where drag reduction is required, the front side of the corona discharge cavity plate (1) is flush with the surface where drag reduction is required, and the device is arranged at a position slightly upstream in the drag reduction area.

7. The turbulent friction drag reduction device based on array corona discharge according to any one of claims 1 to 5, characterized in that: The circuit of the device is connected to a controller (3), and a plurality of small relays are arranged inside the entire circuit to respectively control the voltage polarity on the electrodes of each corona discharge electrode group (5); A plurality of small transformers are arranged to respectively control the DC voltage on each corona discharge cavity plate (1) and the corona discharge electrode (2); and sensors are arranged in the flow field to collect flow field data.

8. The turbulent friction drag reduction device based on array corona discharge according to any one of claims 1 to 5, characterized in that: The device works as follows: For a single corona discharge group, a high-voltage DC power supply (4) generates a DC high voltage, which is applied to the discharge electrode (2), generating a strong electric field between the discharge electrode (2) and the corona discharge cavity plate (1). The electric field strength exceeds a critical value, causing air molecules to collide and ionize to generate a self-sustaining discharge, thereby generating plasma (6) and forming an ion wind. The two oblique jets of each discharge group are coupled to form a spirally rising jet, generating a normal blowing effect in the flow field. A high-voltage direct current power supply (4) is connected to ionize the air to generate plasma (6) to form an ion wind. The two oblique jets of each discharge group are coupled to form a spirally ascending normal jet, so that the bottom fluid of the boundary layer is washed upward to achieve turbulent friction drag reduction.

9. A turbulent friction drag reduction device and method based on array corona discharge, which is based on the turbulent friction drag reduction device based on array corona discharge as claimed in any one of claims 1 to 5, characterized in that: The device works in the following three modes: Mode 1: When a high-voltage DC power supply (4) is connected, the corona discharge cavity plate (1) is the cathode, and the discharge electrode (2) is the anode, plasma (6) is generated between the corona discharge cavity plate (1) and the discharge electrode (2), forming a blowing effect, and plasma jets are generated from the two inclined holes in each group to couple to form a spirally rising normal vortex blowing; Mode 2: When a high-voltage sinusoidal power supply is connected, the corona discharge cavity plate (1) is the cathode and the discharge electrode (2) is the anode, plasma (6) is generated between the corona discharge cavity plate (1) and the discharge electrode (2), forming a blowing effect, and plasma jets are generated from the two inclined holes of each group to couple to form a spiral rising normal vortex blowing, and the blowing intensity of each group of electrodes changes sinusoidally with the voltage; Mode 3: When a high-voltage DC power supply (4) is connected, the corona discharge cavity plate (1) is the anode and the discharge electrode is the cathode, plasma (6) is generated between the corona discharge cavity plate (1) and the discharge electrode (2), forming an air suction effect; The method is specifically as follows: Step S1, the sensor collects flow field data, arranges the sensor in the flow field, collects the temperature, pressure, velocity, wall shear stress and other information in the flow field in real time, and inputs the data into the controller; Step S2, the controller control circuit selects one of the above three working modes, tries the above three working modes in turn and adjusts the voltage of each corona discharge group, the discharge density of the array corona discharge group and other parameters; Step S3, the sensor collects flow field data again to collect flow field information after corona discharge; Step S4, analyzing the data collected by the sensor in the controller, comparing the information before and after the corona discharge, and comparing the changes in the friction resistance measured before and after the corona discharge under the temperature, pressure, and speed conditions. If the measured friction resistance is less than the friction resistance before the corona discharge, the expected drag reduction effect is achieved. Otherwise, return to step S2 and select a new working mode or a new discharge state according to the flow field information; compare the drag reduction effects of different modes to select the optimal drag reduction mode, and the selection method is as follows: when the aircraft is flying at high speed, it is necessary to increase the voltage and increase the density of the corona discharge group to form a thicker air film in the drag reduction arrangement area, effectively reduce the viscous resistance between the air and the wall, and meet the high-speed drag reduction requirements; when flying at low speed, a lower voltage and opening of some corona discharge electrode groups can form an air film of a certain thickness in the drag reduction arrangement area, thereby achieving the drag reduction requirements and saving energy.

10. The turbulent friction drag reduction device and method based on array corona discharge according to claim 9, characterized in that: The surface friction resistance is measured using a surface shear stress sensor.

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