Plasma / lobe combined mixing enhancement test device and system

Abstract

The invention discloses a plasma / lobe combined mixing enhancement test device and a system thereof. The test device comprises: an air intake pipe, a supersonic inlet is provided on the side wall of the air intake pipe, a nozzle, a supersonic through hole is provided on the side wall of the nozzle, the supersonic through hole is used for supersonic air passing through the supersonic inlet of the air intake pipe to enter the nozzle through the supersonic through hole, and a mixing tube, a plurality of positive electrode holes for inserting positive electrodes are provided on one side wall of the mixing tube, and a plurality of negative electrode holes are provided on the other side wall of the mixing tube, so that the subsonic air ejected from the outlet of the air intake pipe and entering the mixing tube and the supersonic air ejected from the rear end of the nozzle are mixed in an electric field and then ejected from the outlet of the mixing tube. The invention provides a guarantee for studying the mixing characteristics of sub-super shear mixed flow under real conditions and provides guidance for the structural optimization design of an embedded rocket ramjet combination engine.

Description

Technical Field

[0001] The invention belongs to the technical field of combined engines, and in particular relates to a plasma / lobe combined mixing enhancement test device and a system thereof. Background Art

[0002] The study of sub-super shear mixing flow is one of the important research areas in turbulence research. For example, the mixing of the main rocket gas and the incoming air in the combustion chamber of a rocket ramjet is a typical shear mixing flow. Shear mixing flow is a turbulent flow structure formed by the shear mixing and development of two fluids with the same direction and different speeds. It often occurs in the operation of aerospace vehicles. The velocity gradient often limits the mixing efficiency of the two airflows, which seriously affects the working performance of the aircraft. Therefore, in-depth research on the development process of shear mixing flow and exploring methods to enhance mixing have broad theoretical significance and engineering value.

[0003] In recent years, air-breathing engines have shown good application prospects in reusable launch vehicles and hypersonic aircraft. The embedded rocket ramjet engine combines the advantages of both rocket engines and ramjet engines, which can effectively solve the problems of ramjet engines being unable to take off on their own, poor high-altitude performance, low specific impulse of rocket engines, and excessive take-off weight. The embedded rocket ramjet engine has two main working modes: when working at cruising altitude, the embedded rocket does not work, and the combined engine works in a ramjet form; when the working altitude or speed does not meet the requirements of ramjet work, the embedded rocket is started, and the high-temperature gas ejected by the embedded rocket is used to promote efficient combustion in the ramjet engine combustion chamber.

[0004] However, the embedded rocket ramjet engine still faces many difficulties in operation. When the embedded rocket is working, the high-temperature and high-speed flow ejected by the rocket interacts with the low-temperature and low-speed air flow in the main combustion chamber to form a large gradient sub-supershear mixed flow. The large velocity difference and temperature difference between the two jets make the thickness of the low-pressure large gradient shear mixed flow formed between the jets grow abnormally slowly along the flow direction, affecting the energy and momentum transfer between the two jets, resulting in low overall combustion efficiency of the main ramjet combustion chamber, and the fuel energy cannot be fully utilized, which seriously affects the working characteristics of the ramjet combination engine and becomes one of the technical bottlenecks in the development of the ramjet combination engine. Therefore, it is very necessary to carry out research on the mixing enhancement method of large gradient sub-supershear mixed flow, enhance the mixing efficiency of large gradient sub-supershear mixed flow, realize the rapid mixing and combustion of fuel and oxidant, and improve engine performance.

[0005] Existing mixing enhancement methods are mainly divided into passive mixing enhancement methods and active mixing enhancement methods. Passive enhancement technology mainly uses mechanical methods to disrupt the flow field, thereby producing large-scale coherent structures, such as various small tabs, tooth-shaped trailing edge configurations set at the outlet position, and various other studies on the geometric configuration of the outlet. Passive enhancement technology only requires simple design modifications and changes in the geometric shape of the outlet, and its components are easy to manufacture due to its simplicity, so it has a certain appeal. Active enhancement technology mainly disrupts the flow field by introducing vibration pulses, thereby enhancing mixing. However, active enhancement methods are more complicated than passive enhancement methods. Currently, there are few studies at home and abroad, and they are mainly at the conceptual research stage.

[0006] Since the structure of the embedded rocket ramjet combination engine is relatively complex, it is considered to study only the sub-super shear mixing flow, that is, to build a sub-super shear mixing flow test system without considering the engine combustion, to study its mixing process. In terms of experimental technology, the existing test system has the ability to simulate cold and high-temperature gas, which can simulate the mixing state of supersonic jets and subsonic jets at room temperature, and use a small rocket to generate high-temperature supersonic gas and mix with subsonic jets. However, the engine is in the air at high altitude in the actual flight state, and the back pressure is in a low back pressure state. The flow field and mixing efficiency of the sub-super shear mixing flow will change under low back pressure conditions. The air jet on the subsonic side is in a high temperature state after compression, and the temperature can reach up to 800K. High temperature will change the physical properties of the fluid, thereby affecting the subsequent mixing flow. Limited by the high-speed airflow, the existing test scheme usually uses an electric heating belt to heat the flow in the tube, and the subsonic air heating temperature does not exceed 500K, which is a large gap from the actual use temperature. In terms of mixing enhancement, the passive enhancement scheme of concave cavity baffle was experimentally verified. The mixing effect was evaluated to be about 50% based on the thickness of the shear mixing layer. The mixing effect needs to be further improved, and there is a negative impact of large total pressure loss. In addition, due to the disadvantages of the passive mixing scheme being difficult to adjust and immutable, the mixing action range is only at the entrance of the combustion chamber, and the sub-super shear flow mixing process is difficult to achieve full-process control and adjustment. It is necessary to explore the application of active enhancement technology in mixing enhancement. Summary of the invention

[0007] The purpose of the present invention is to provide a plasma / lobe combined mixing enhancement test device and a system thereof, so as to increase the temperature of subsonic air and improve the effect of mixing subsonic air and supersonic air.

[0008] The present invention adopts the following technical scheme: a plasma / lobe combined mixing enhancement test device, comprising:

[0009] The inlet of the air intake pipe is connected to the outlet of the air compressor. The air compressor is used to deliver subsonic air to the air intake pipe. A supersonic inlet is opened on the side wall of the air intake pipe.

[0010] The nozzle is located in the inner cavity of the air intake pipe and is coaxially arranged with the air intake pipe. The end facing the air intake pipe is the front end, and the other end is the rear end. The front end opening is closed, and a supersonic through hole is opened on the side wall. The supersonic through hole is used for supersonic air passing through the supersonic inlet of the air intake pipe to enter the nozzle through the supersonic through hole, and is ejected from the rear end of the nozzle after being accelerated in the nozzle.

[0011] The mixing tube is coaxially arranged with the air intake pipe, and its inlet is connected with the outlet of the air intake pipe. A plurality of positive electrode holes for inserting positive electrodes are opened on one side wall, and a plurality of negative electrode holes for inserting negative electrodes are opened on the other side wall. The positive electrode and the negative electrode are connected to an external power supply and are symmetrically arranged, and are used to generate an electric field between the two, so that the subsonic air ejected from the outlet of the air intake pipe and entering the mixing tube and the supersonic air ejected from the rear end of the nozzle are mixed in the electric field and then ejected from the outlet of the mixing tube.

[0012] Furthermore, a petal-shaped disturbance plate is provided at the outlet of the nozzle, the axis of the disturbance plate is parallel to the axis of the nozzle, the front end of the disturbance plate is fixedly connected to the rear end of the nozzle, and the rear end is arranged toward the mixing tube.

[0013] Furthermore, two disturbance plates are provided, and are symmetrically arranged up and down.

[0014] Furthermore, it also includes: an inlet pipe, whose axis is perpendicular to the axis of the intake pipe, whose inlet end is connected to the supersonic air system, and whose outlet end passes through the supersonic inlet of the intake pipe and the supersonic through hole of the nozzle in sequence and then is connected to the nozzle, so as to transport supersonic air to the nozzle.

[0015] Furthermore, the amplitude of the disturbance plate is 0.5-2 mm, the wavelength is 2.5-10 mm, and the lobe angle is 5.7-21.8°.

[0016] Plasma / lobe combined mixing enhancement test system, including:

[0017] The inlet of the heating tube is connected to the outlet of the air compressor, and the air compressor is used to deliver subsonic air to the heating tube.

[0018] The electric heating device is used to heat the heating tube, so that the temperature of the subsonic air in the heating tube rises.

[0019] The inlet of the air intake pipe is connected with the outlet of the heating pipe. The inlet of the air intake pipe is used for the heated subsonic air to enter. A supersonic inlet is provided on the side wall of the air intake pipe. The supersonic inlet is used for the supersonic air to enter.

[0020] The nozzle is located in the inner cavity of the air intake pipe and is coaxially arranged with the air intake pipe. The end facing the air intake pipe is the front end, and the other end is the rear end. The front end opening is closed, and a supersonic through hole is opened on the side wall. The supersonic through hole is used for supersonic air passing through the supersonic inlet of the air intake pipe to enter the nozzle through the supersonic through hole, and is ejected from the rear end of the nozzle after being accelerated in the nozzle.

[0021] The mixing tube is coaxially arranged with the air intake pipe, and its inlet is connected with the outlet of the air intake pipe. A plurality of positive electrode holes for inserting positive electrodes are opened on one side wall, and a plurality of negative electrode holes for inserting negative electrodes are opened on the other side wall. The positive electrode and the negative electrode are connected to an external power supply and are symmetrically arranged, and are used to generate an electric field between the two, so that the subsonic air ejected from the outlet of the air intake pipe and entering the mixing tube and the supersonic air ejected from the rear end of the nozzle are mixed in the electric field and then ejected from the outlet of the mixing tube.

[0022] Furthermore, it also includes: a vacuum tank (10) and a vacuum pump (11), wherein the inlet of the vacuum tank (10) is connected to the outlet of the mixing tube, and the outlet is connected to the vacuum pump (11), and the vacuum pump (11) is used to generate back pressure at the outlet of the mixing tube.

[0023] Furthermore, the electric heating device comprises:

[0024] The induction copper tube is wound around the outer wall of the heating tube. Both ends of the induction copper tube are connected to the power supply to generate microwaves to heat the metal material inside the air path under the action of electricity, thereby heating the subsonic air in the heating tube.

[0025] Furthermore, it also includes: an inlet pipe, whose axis is perpendicular to the axis of the intake pipe, whose inlet end is connected to the supersonic air system, and whose outlet end passes through the supersonic inlet of the intake pipe and the supersonic through hole of the nozzle in sequence and then is connected to the nozzle, so as to transport supersonic air to the nozzle.

[0026] The beneficial effects of the present invention are as follows: the present invention adopts a high-frequency induction microwave electric heating device to heat the subsonic side air jet to achieve the actual high temperature state of the subsonic airflow, and by setting a vacuum pump, the low back pressure working state simulation of the embedded rocket ramjet combination engine is realized, and the DBD plasma discharge technology is adopted to regulate the sub-super shear layer flow field, increase the instability of the flow field and thus improve the mixing efficiency, and the discharge intensity in different areas can be adjusted by changing the electrode layout to achieve spatial precision mixing; a nozzle with a disturbance plate is provided to introduce a streamwise vortex and a lateral vortex into the shear layer to improve the mixing efficiency, and different mixing effects and total pressure losses are achieved by changing the wavelength and amplitude of the disturbance plate; the present invention provides a guarantee for studying the mixing characteristics of the sub-super shear mixing flow under the real state, and provides guidance for the structural optimization design of the embedded rocket ramjet combination engine, thereby providing a reference basis and effective support for improving the combustion efficiency of the embedded rocket ramjet combination engine, and finally achieving the purpose of improving the engine performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the cross-sectional structure of the device of the present invention;

[0028] Figure 2 It is a structural schematic diagram of the system of the present invention;

[0029] Figure 3 It is a schematic diagram of the structure of the disturbance plate of the present invention.

[0030] Among them: 1. Intake pipe; 2. Nozzle; 3. Supersonic inlet; 4. Positive electrode; 5. Mixing tube; 6. Heating tube; 7. Induction copper tube; 8. Disturbance plate; 9. Introductory tube; 10. Vacuum tank; 11. Vacuum pump. DETAILED DESCRIPTION

[0031] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] The present invention discloses a plasma / lobe combined mixing enhancement test device, such as Figure 1 As shown, it includes: an air intake pipe 1, a nozzle 2, and a mixing pipe 5.

[0033] The inlet of the intake pipe 1 is connected with the outlet of the air compressor. The air compressor is used to deliver subsonic air to the intake pipe 1. A supersonic inlet 3 is provided on the side wall of the intake pipe 1. The nozzle 2 is located in the inner cavity of the intake pipe 1 and is coaxially arranged with the intake pipe 1. The end of the nozzle 2 facing the intake pipe 1 is the front end, and the other end of the nozzle 2 is the rear end. The front end opening of the nozzle 2 is closed. A supersonic through hole is provided on the side wall of the nozzle 2. The supersonic through hole is used for supersonic air passing through the supersonic inlet 3 of the intake pipe 1 to pass through the supersonic through hole into the nozzle 2, and to be ejected from the rear end of the nozzle 2 after being accelerated in the nozzle 2.

[0034] The mixing tube 5 is coaxially arranged with the air intake pipe 1, and its inlet is connected with the outlet of the air intake pipe 1. A plurality of positive electrode holes for inserting the positive electrode 4 are opened on one side wall of the mixing tube 5, and a plurality of negative electrode holes for inserting the negative electrode are opened on the other side wall of the mixing tube 5. The positive electrode 4 and the negative electrode are connected to an external power supply and are symmetrically arranged, and are used to generate an electric field between the two, so that the subsonic air ejected from the outlet of the air intake pipe 1 and entering the mixing tube 5 and the supersonic air ejected from the rear end of the nozzle 2 are mixed in the electric field and then ejected from the outlet of the mixing tube 5.

[0035] In order to achieve active enhanced control of the shear mixing layer, DBD plasma discharge technology is used to regulate the sub-super shear layer flow field. The discharge intensity in different areas of the mixing tube 5 is adjusted by the layout of the positive electrode 4 and the negative electrode to achieve spatial precise mixing. After the high-voltage power supply is started, the electrode discharges and breaks through the central high-speed airflow, which can achieve control of the sub-super shear layer flow field and increase the development rate of the shear layer, thereby enhancing the mixing efficiency. The mixing effect can also be regulated by changing the spacing and number of electrodes.

[0036] like Figure 3 As shown, a petal-shaped disturbance plate 8 is provided at the outlet of the nozzle 2, the axis of the disturbance plate 8 is parallel to the axis of the nozzle 2, the front end of the disturbance plate 8 is fixedly connected to the rear end of the nozzle 2, and the rear end of the disturbance plate 8 is arranged toward the mixing tube 5. Two disturbance plates 8 are provided, and they are symmetrically arranged up and down. The amplitude of the disturbance plate 8 is 0.5-2mm, the wavelength is 2.5-10mm, and the petal angle is 5.7-21.8°.

[0037] In order to further strengthen the mixing of the shear mixing layer, a disturbance plate 8 is provided at the outlet of the nozzle 2. The disturbance plate 8 can also be arc-shaped or "S"-shaped. The disturbance plate 8 can generate large-scale streamwise vortices and transverse vortices, thereby achieving the purpose of enhancing mixing. At the same time, the wavelength and amplitude of the lobe can be changed to achieve different mixing effects and reduce the total pressure loss. Combined with the number and voltage of the activated plasma electrodes, the mixing effect can be further improved.

[0038] The plasma / lobe combined mixing enhancement test device also includes: an introduction pipe 9, the axis of the introduction pipe 9 is perpendicular to the axis of the intake pipe 1, the inlet end of the introduction pipe 9 is connected to the supersonic air system, and the outlet end of the introduction pipe 9 passes through the supersonic inlet 3 of the intake pipe 1 and the supersonic through hole of the nozzle 2 in sequence and then is connected to the nozzle 2. The introduction pipe 9 is used to transport supersonic air to the nozzle 2.

[0039] like Figure 2 As shown, the present invention also discloses a plasma / lobe combined mixing enhancement test system, which includes: a heating tube 6, an electric heating device, an air intake pipe 1, a nozzle 2, and a mixing tube 5.

[0040] The inlet of the heating pipe 6 is connected with the outlet of the air compressor. The air compressor is used to transport subsonic air to the heating pipe 6. The electric heating device is used to heat the heating pipe 6 so that the temperature of the subsonic air in the heating pipe 6 rises. The inlet of the intake pipe 1 is connected with the outlet of the heating pipe 6. The inlet of the intake pipe 1 is used for the heated subsonic air to enter. A supersonic inlet 3 is provided on the side wall of the intake pipe 1. The supersonic inlet 3 is used for the supersonic air to enter.

[0041] The nozzle 2 is located in the inner cavity of the intake pipe 1 and is coaxially arranged with the intake pipe 1. The end of the nozzle 2 facing the intake pipe 1 is the front end, and the other end of the nozzle 2 is the rear end. The front end opening of the nozzle 2 is closed, and a supersonic through hole is opened on the side wall of the nozzle 2. The supersonic through hole is used for supersonic air passing through the supersonic inlet 3 of the intake pipe 1 to enter the nozzle 2 through the supersonic through hole, and to be ejected from the rear end of the nozzle 2 after being accelerated in the nozzle 2.

[0042] The mixing tube 5 is coaxially arranged with the air intake pipe 1, and its inlet is connected with the outlet of the air intake pipe 1. A plurality of positive electrode holes for inserting the positive electrode 4 are opened on one side wall of the mixing tube 5, and a plurality of negative electrode holes for inserting the negative electrode are opened on the other side wall of the mixing tube 5. The positive electrode 4 and the negative electrode are connected to an external power supply and are symmetrically arranged, and are used to generate an electric field between the two, so that the subsonic air ejected from the outlet of the air intake pipe 1 and entering the mixing tube 5 and the supersonic air ejected from the rear end of the nozzle 2 are mixed in the electric field and then ejected from the outlet of the mixing tube 5.

[0043] The plasma / lobe combined mixing and strengthening test system also includes: a vacuum tank 10 and a vacuum pump 11. The inlet of the vacuum tank 10 is connected to the outlet of the mixing tube 5. The outlet of the vacuum tank 10 is connected to the vacuum pump 11. The vacuum pump 11 is used to generate back pressure at the outlet of the mixing tube 5. The mixing tube 5 is evacuated by the vacuum pump 11, thereby achieving the environmental requirement of a low back pressure of 0.1atm. The volume of the vacuum tank 10 is 3m 3 The reason for selecting the vacuum tank 10 of this volume specification is that the volume is too small, which makes it extremely difficult to maintain the pressure of the vacuum tank 10 during the test; the volume is too large, which makes the suction time of the vacuum tank 10 too long, and it is difficult to achieve variable pressure control of the vacuum tank 10; furthermore, the volume of the vacuum tank 10 is too large, and the sealing conditions become more and more harsh, requiring a lot of effort for equipment maintenance.

[0044] The plasma / lobe combined mixing enhancement test system also includes: an introduction pipe 9, the axis of the introduction pipe 9 is perpendicular to the axis of the intake pipe 1, the inlet end of the introduction pipe 9 is connected to the supersonic air system, and the outlet end of the introduction pipe 9 passes through the supersonic inlet 3 of the intake pipe 1 and the supersonic through hole of the nozzle 2 in sequence and then is connected to the nozzle 2. The introduction pipe 9 is used to transport supersonic air to the nozzle 2.

[0045] The electric heating device includes: an induction copper tube 7, which is wound around the outer wall of the heating tube 6, and both ends of the induction copper tube 7 are connected to a power source. The induction copper tube 7 is used to generate microwaves under the action of electricity to heat the metal material inside the air path, thereby heating the subsonic air in the heating tube 6. The induction copper tube 7 is evenly wrapped around the heating tube 6, so that the heating tube 6 heats up quickly and transfers the heat to the high-speed air through heat conduction. The heating tube 6 is equipped with fins to slow down the air speed and increase the residence time in the heating tube 6. At the same time, the heat exchange area is also greatly increased, thereby greatly improving the convective heat exchange efficiency.

[0046] Existing technologies face the following challenges:

[0047] 1. Because the subsonic air speed is above 100m / s, the convective heat transfer of air in the high-speed flow state is very difficult. Conventional electric heating devices can only heat to about 473K, which is difficult to simulate the actual ram air temperature.

[0048] 2. The ground ambient pressure is one standard atmospheric pressure. It is very difficult to provide an ignition working back pressure environment of about 0.1atm at high altitude on the ground.

[0049] 3. Conventional passive enhancement configurations have low mixing efficiency. For example, the mixing effect of cavities and bosses in sub-supershear layers is only 50%. In addition, the above configurations bring more than 40% total pressure loss due to sudden expansion, which weakens the specific impulse performance and affects the mixing efficiency.

[0050] 4. The passive mixing scheme is difficult to adjust, and the mixing effect range is only at the inlet partition of the combustion chamber. The sub-super shear layer mixing process is difficult to achieve full-process control.

[0051] Therefore, in order to fully understand the mixing layer growth characteristics of the sub-super shear layer under low back pressure hot conditions, the plasma / lobe combined mixing enhancement test system adds a high-frequency induction microwave electric heating device at the inlet of the heating tube 6, that is, the air path inlet to heat the subsonic side air jet, so that the subsonic airflow is close to the actual high temperature state; three vacuum pumps 11 are set to form a low-pressure vacuum system to provide a low back pressure environment for the sub-supersonic mixing flow; in order to achieve efficient and controllable mixing of the sub-super shear layer, 14 high-voltage electrodes are installed on the side wall of the mixing tube 5, and plasma is applied in the flow field to promote sub-super shear layer mixing; a disturbance plate 8 is set at the outlet of the nozzle 2 to introduce lateral vortices and streamwise vortices in the sub-super shear layer, thereby improving the mixing efficiency; in addition, the mixing effect is greatly improved by using a combination of plasma / lobes, and the mixing efficiency at different positions is accurately adjusted.

[0052] The working process of the plasma / lobe combined mixing enhancement test system of the present invention is as follows:

[0053] Turn on the power supply of the electric heating device and the circulating cooling water, and the high-frequency induction microwave electric heating device starts to work. After preheating for 60 seconds, turn on the combined vacuum pump 11 in turn to pump the vacuum tank 10 to a low back pressure environment, then open the ball valve of the vacuum tank 10 and the subsonic inlet vacuum ball valve. Under the suction action of the vacuum suction system, the air enters the heating tube 6 from the atmospheric environment through the subsonic inlet vacuum ball valve. In this process, the air is heated by the high-temperature fins for heat exchange, and a subsonic airflow is formed on the upper and lower sides of the intake pipe 1. After the subsonic airflow is stable, open the solenoid valves of the oxygen and ethylene pipelines to pass the gas into the gas generator, turn on the high-frequency igniter to ignite the gas, and the high-temperature and high-pressure airflow generated after combustion enters the nozzle 2 through the introduction pipe 9, and a supersonic airflow is generated. The sub- and supersonic airflows are sheared and mixed in the mixing tube 5, and then the mixed airflow flows out of the mixing tube 5 for cooling. The cooled gas is passed into the vacuum tank 10. The experiment lasts for 20 seconds.

[0054] When the sub- and super-flows are working stably for 5 seconds, the plasma high voltage power supply is turned on, and the electrode starts to discharge, causing disturbances in the flow field. By adjusting the voltage, the mixing effect of the plasma intensity on the mixed flow field is compared. After the experiment is completed, the disturbance plate 8 is fixed on the nozzle 2, and the mixing enhancement effect under the plasma / lobe combination conditions is compared to determine the optimal enhancement working conditions and methods.

[0055] More specifically, the test process of the plasma / lobe combined mixing enhancement test system of the present invention is as follows:

[0056] (1) Test whether the acquisition system is normal.

[0057] (2) Cut off the gas source valves of the oxygen line and the ethylene line, and check whether the solenoid valves of the two lines are working normally.

[0058] (3) Before each ignition test, check whether the igniter is working properly.

[0059] (4) Check whether the plasma electrode is working properly.

[0060] (5) The gas source pressure of the oxygen circuit is adjusted between 1.95 and 2.17 MPa, and the gas source pressure of the ethylene circuit is adjusted between 0.97 and 1.15 MPa.

[0061] (6) Before starting the test, close the subsonic inlet valve and open the vacuum tank 10 valve to check and confirm that the test system is airtight.

[0062] (7) Turn on the refrigerator to cool the connecting pipe between the system and the vacuum tank 10 in advance.

[0063] (8) Turn on the heater to circulate cooling water to keep the high-frequency induction microwave electric heating device working for a long time.

[0064] (9) The heater power is turned on, and the high-frequency induction microwave electric heating device starts heating the heating tube 6 and the fins.

[0065] (10) Turn on the vacuum pump 11 to reduce the pressure in the vacuum tank 10 to below 1000 Pa.

[0066] (11) The test section acquisition system is turned on and data collection begins;

[0067] (12) Manually open the control valve and subsonic inlet valve between the vacuum tank 10 and the mixing tube 5, and the experimenters evacuate quickly;

[0068] (13) After confirming that the test personnel have evacuated, open the solenoid valve of the oxygen circuit, open the solenoid valve of the ethylene circuit 1 second later, and open the igniter to ignite 1 second later.

[0069] (14) After successful ignition, the plasma high voltage power supply was turned on after an interval of 5 seconds, and the change in shear layer thickness was captured by a high-speed camera and a schlieren system.

[0070] (15) Adjust the power supply and capture the mixing effect under different plasma intensities.

[0071] (16) After 15 seconds, close the solenoid valves on the oxygen and ethylene lines to cut off the supply of fuel gas and oxygen, thus terminating combustion.

[0072] (17) The subsonic inlet valve continues to open, and the mechanical pump draws ambient air to disperse the gas in the vacuum tank 10.

[0073] (18) Turn off the mechanical pump, and close the subsonic inlet valve and the vacuum tank 10 valve.

[0074] (19) Turn off the heater power supply and turn off the heater cooling system after 60 seconds.

[0075] (20) The collected data is exported from the test system, and then the thermocouple voltage value is read and converted into a temperature value through the Origin post-processing software, and the shear layer temperature distribution curve is obtained, and the thickness and thickness growth rate of the shear mixing layer are calculated.

[0076] (21) Replace the nozzle 2 with a disturbance plate 8 having a different wavelength and amplitude, and repeat the above experimental steps.

[0077] (22) The thickness growth rate of the shear mixing layer under different plasma intensities and characteristic parameters of the disturbance plate 8 is analyzed to determine the optimal active and passive combined flow control scheme.

[0078] This system provides high-temperature subsonic air and low back pressure environment for ground tests of large-gradient sub-supershear mixing flows, and solves the problem of low mixing efficiency of high-temperature sub-supershear flow mixing layers. Therefore, one of the key points is to introduce a high-frequency induction microwave electric heating device to heat the subsonic side air jet. Under this condition, the subsonic air can be heated to above 600K, which is 130K higher than the temperature of the existing electric heating system; the second key point is to introduce a low-pressure vacuum system composed of a vacuum pump 11, and to achieve a low back pressure environment and flexibly adjust the back pressure by controlling the vacuum pump suction time and the number of openings; the third key point is to densely distribute plasma electrodes at different positions along the mixing pipe 5, and to achieve the increase in the thickness of the sub-supershear mixing layer by changing the plasma intensity; the fourth key point is to set a nozzle 2 with a disturbance plate 8, and change the wavelength and amplitude of the disturbance plate 8 to achieve different mixing effects and reduce the total pressure loss.

[0079] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A plasma / lobe combined mixing enhancement test device, characterized in that: include: An air intake pipe (1) has an inlet connected to an outlet of an air compressor, the air compressor being used to deliver subsonic air to the air intake pipe (1), and a supersonic inlet (3) is provided on a side wall of the air intake pipe (1). The nozzle (2) is located in the inner cavity of the air intake pipe (1) and is coaxially arranged with the air intake pipe (1). The end of the nozzle (2) facing the air intake pipe (1) is the front end, and the other end is the rear end. The front end opening is closed, and a supersonic through hole is provided on the side wall. The supersonic through hole is used for supersonic air passing through the supersonic inlet (3) of the air intake pipe (1) to enter the nozzle (2) through the supersonic through hole, and to be ejected from the rear end of the nozzle (2) after being accelerated in the nozzle (2). A mixing tube (5) is coaxially arranged with the air intake pipe (1), and its inlet is connected to the outlet of the air intake pipe (1). A plurality of positive electrode holes for inserting positive electrodes (4) are provided on one side wall thereof, and a plurality of negative electrode holes for inserting negative electrodes are provided on the other side wall thereof. The positive electrode (4) and the negative electrode are connected to an external power source and are symmetrically arranged, and are used to generate an electric field between the two, so that the subsonic air ejected from the outlet of the air intake pipe (1) and entering the mixing tube (5) and the supersonic air ejected from the rear end of the nozzle (2) are mixed in the electric field and ejected from the outlet of the mixing tube (5); A petal-shaped disturbance plate (8) is provided at the outlet of the nozzle (2), the axis of the disturbance plate (8) being parallel to the axis of the nozzle (2), the front end of the disturbance plate (8) being fixedly connected to the rear end of the nozzle (2), and the rear end of the disturbance plate (8) being arranged toward the mixing tube (5); The electric heating device comprises: an induction copper tube (7) wound around the outer wall of a heating tube (6), both ends of the induction copper tube (7) being connected to a power source and used to generate microwaves under the action of electricity to heat the metal material inside the air path, thereby heating the subsonic air in the heating tube (6).

2. The plasma / lobe combined mixing enhancement test device according to claim 1, characterized in that: The disturbance plates (8) are provided with two, and are symmetrically arranged up and down.

3. The plasma / lobe combined mixing enhancement test device according to claim 2, characterized in that: It also includes: an introduction pipe (9), the axis of which is perpendicular to the axis of the intake pipe (1), the inlet end of which is connected to the supersonic air system, and the outlet end of which passes through the supersonic inlet (3) of the intake pipe (1) and the supersonic through hole of the nozzle (2) in sequence and then communicates with the nozzle (2), so as to transport supersonic air to the nozzle (2).

4. The plasma / lobe combined mixing enhancement test device according to claim 2, characterized in that: The disturbance plate (8) has an amplitude of 0.5-2 mm, a wavelength of 2.5-10 mm, and a lobe angle of 5.7-21.8°.

5. A plasma / lobe combined mixing enhancement test system, characterized in that: include: The heating pipe (6) has an inlet connected to an outlet of an air compressor, and the air compressor is used to deliver subsonic air to the heating pipe (6). an electric heating device, used to heat the heating tube (6) so that the temperature of the subsonic air in the heating tube (6) rises, An air intake pipe (1) has an inlet connected to an outlet of the heating pipe (6), the inlet of the air intake pipe (1) is used for heated subsonic air to enter, a supersonic inlet (3) is provided on a side wall of the air intake pipe (1), and the supersonic inlet (3) is used for supersonic air to enter. The nozzle (2) is located in the inner cavity of the air intake pipe (1) and is coaxially arranged with the air intake pipe (1). The end of the nozzle (2) facing the air intake pipe (1) is the front end, and the other end is the rear end. The front end opening is closed, and a supersonic through hole is provided on the side wall. The supersonic through hole is used for supersonic air passing through the supersonic inlet (3) of the air intake pipe (1) to enter the nozzle (2) through the supersonic through hole, and to be ejected from the rear end of the nozzle (2) after being accelerated in the nozzle (2). A mixing tube (5) is coaxially arranged with the intake tube (1), and its inlet is connected to the outlet of the intake tube (1); a plurality of positive electrode holes for inserting the positive electrode (4) are provided on one side wall thereof, and a plurality of negative electrode holes for inserting the negative electrode are provided on the other side wall thereof; the positive electrode (4) and the negative electrode are connected to an external power source and are symmetrically arranged, and are used to generate an electric field between the two, so that the subsonic air ejected from the outlet of the intake tube (1) and entering the mixing tube (5) and the supersonic air ejected from the rear end of the nozzle (2) are mixed in the electric field and ejected from the outlet of the mixing tube (5); A petal-shaped disturbance plate (8) is provided at the outlet of the nozzle (2), the axis of the disturbance plate (8) being parallel to the axis of the nozzle (2), the front end of the disturbance plate (8) being fixedly connected to the rear end of the nozzle (2), and the rear end of the disturbance plate (8) being arranged toward the mixing tube (5); The electric heating device comprises: an induction copper tube (7) wound around the outer wall of the heating tube (6), both ends of the induction copper tube (7) being connected to a power source and used to generate microwaves under the action of electricity to heat the metal material inside the air path, thereby heating the subsonic air in the heating tube (6).

6. The plasma / lobe combined mixing enhancement test system according to claim 5, characterized in that: Also includes: A vacuum tank (10) and a vacuum pump (11), wherein the inlet of the vacuum tank (10) is connected to the outlet of the mixing tube (5), and the outlet of the vacuum tank (10) is connected to the vacuum pump (11), and the vacuum pump (11) is used to generate back pressure at the outlet of the mixing tube (5).

7. The plasma / lobe combined mixing enhancement test system according to claim 6, characterized in that: It also includes: an introduction pipe (9), the axis of which is perpendicular to the axis of the intake pipe (1), the inlet end of which is connected to the supersonic air system, and the outlet end of which passes through the supersonic inlet (3) of the intake pipe (1) and the supersonic through hole of the nozzle (2) in sequence and then communicates with the nozzle (2), so as to transport supersonic air to the nozzle (2).

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