Method of plasma-assisted jet control of scramjet engine operating mode

Abstract

A device for controlling the operating modes of a scramjet engine using plasma-assisted jet injection is provided, comprising an isolation section (1), a combustion chamber (2), a nozzle (3), a plasma-assisted jet injector (12), an injection jet (13), and a cavity (14). A method for controlling the operating modes of a scramjet engine using plasma-assisted jet injection is also provided. This invention improves the combustion efficiency of the engine by injecting a plasma-assisted jet into the engine channel, enabling continuous adjustment of the engine's operating modes while reducing the complexity of the mode adjustment mechanism.

Description

Technical Field

[0001] The invention belongs to the field of aerospace technology, and in particular relates to a method for regulating the working mode of a scramjet engine with plasma-assisted jet. Background Art

[0002] Scramjet engines have high performance at high flight Mach numbers, making them the first choice for high-speed aircraft propulsion systems. Scramjet engines are generally composed of components such as an air inlet, an isolation section, a combustion chamber, and a nozzle. At different flight speeds, the working modes of scramjet engines are different. When the flight speed is relatively low, a strong shock wave train is formed in the isolation section, and the engine is in a sub-combustion working mode. When the flight speed is relatively high, a weak shock wave train is formed in the isolation section, and the engine is in a scramjet working mode. The different working modes of scramjet engines result in different combustion chamber combustion efficiency, engine internal resistance, and engine thrust performance. Therefore, it is necessary to develop a method for regulating the working mode of scramjet engines to achieve controllable engine performance.

[0003] The existing active control methods of scramjet engine working mode mainly include changing the fuel equivalence ratio, changing the injection position, etc. Studies have shown that by increasing the fuel flow rate, the scramjet engine can enter the subcombustion mode from the weak combustion scramjet mode; by setting the injection position at the front end of the combustion chamber under low Mach number flight conditions and moving the injection backward under high Mach number flight conditions, the scramjet engine working mode conversion can be achieved.

[0004] The conversion of scramjet combustion mode by changing the fuel equivalence ratio can easily lead to low engine combustion efficiency and affect the engine thrust performance during actual flight. The conversion of scramjet combustion mode by changing the fuel injection position cannot achieve continuous adjustment of the engine working mode due to the limited number of injection positions that can be changed, which can easily lead to low combustion chamber efficiency. Summary of the invention

[0005] In view of the problem that different operating modes of scramjet engines lead to different engine performances, the present invention provides a device for regulating the operating mode of a scramjet engine by a plasma-assisted jet, hereinafter referred to as "plasma-assisted jet regulating engine mode device", which includes an isolation section 1, a combustion chamber 2, a nozzle 3, a plasma-assisted ejector 12, an injection 13, and a concave cavity 14; the cavity width of the entire device remains unchanged; wherein

[0006] The isolation section 1 adopts a uniform cross-section configuration, and is composed of an isolation section left wall 4-1, an isolation section right wall 5-1, an isolation section upper wall 6 and an isolation section lower wall 7; the ratio of the isolation section inlet height to the inlet width is less than 1, the isolation section outlet size is the same as the inlet size, and the isolation section upper wall 6 and the isolation section lower wall 7 are both parallel to the horizontal plane;

[0007] The combustion chamber 2 is composed of a left combustion chamber wall 4-2, a right combustion chamber wall 5-2, an upper combustion chamber wall 8 and a lower combustion chamber wall 9, and is a unilateral expansion configuration with a certain expansion angle; the left combustion chamber wall 4-2 is integrated with the left wall 4-1 of the isolation section and is coplanar, the right combustion chamber wall 5-2 is integrated with the right wall 5-1 of the isolation section and is coplanar, the upper combustion chamber wall 8 is integrated with the upper isolation section wall 6 and is coplanar, the lower combustion chamber wall 9 is integrated with the lower isolation section wall 7, but the lower combustion chamber wall 9 expands downward at a certain angle; the inlet size of the combustion chamber 2 is the same as the outlet size of the isolation section 1; the combustion chamber is provided with a plasma auxiliary ejector 12, a fuel injection 13, and a concave cavity 14, as follows;

[0008] The concave cavity 14 is approximately located in the middle of the combustion chamber 2, and is composed of a front wall, a rear wall and a bottom wall; the front wall of the concave cavity is perpendicular to the lower wall 9 of the combustion chamber, and the bottom wall of the concave cavity is parallel to the lower wall 9 of the combustion chamber; the rear wall of the concave cavity is a convergent configuration, and it forms a certain angle with the plane where the lower wall 9 of the combustion chamber is located; the ratio of the height of the front wall of the concave cavity to the length of the bottom wall of the concave cavity is less than 10, and the width of the concave cavity is the same as the width of the lower wall 9 of the combustion chamber;

[0009] A fuel injection 13 is arranged on the bottom wall of the concave cavity. The fuel injection 13 is a through hole that penetrates the lower body of the plasma-assisted jet control engine mode device from bottom to top. The outlet of the through hole is located at the center position between the left wall 4-2 of the combustion chamber and the right wall 5-2 of the combustion chamber.

[0010] A plasma-assisted ejector 12 is installed upstream of the concave cavity 14, which includes a through hole penetrating from bottom to top through the body below the plasma-assisted ejector regulating engine mode device and a plasma-assisted ejector fixedly installed in the through hole, and the shape of the through hole is designed to adapt to the shape of the plasma-assisted ejector; the plasma-assisted ejector 12 is at a certain distance from the front wall of the concave cavity;

[0011] The nozzle 3 is composed of an upper nozzle wall 10, a lower nozzle wall 11, a left nozzle wall 4-3 and a right nozzle wall 5-3, and adopts a bilateral expansion configuration with an expansion angle of θ2; the nozzle inlet size is the same as the combustion chamber outlet size; the left nozzle wall 4-3 is integrated with the left combustion chamber wall 4-2 and are coplanar, the right nozzle wall 5-3 is integrated with the right combustion chamber wall 5-2 and are coplanar, the upper nozzle wall 10 is integrated with the upper combustion chamber wall 8, but the upper nozzle wall 10 expands upward from the upper combustion chamber wall 8 by a certain angle, the lower nozzle wall 11 is integrated with the lower combustion chamber wall 9, but the lower nozzle wall 11 expands downward from the lower combustion chamber wall 9 by a certain angle.

[0012] In a specific embodiment of the present invention, the ratio of the isolation segment inlet height to the inlet width of the isolation segment 1 is 1:2; and the expansion angle of the combustion chamber is 2 degrees.

[0013] In another specific embodiment of the present invention, the angle between the rear wall of the cavity and the plane where the lower wall 9 of the combustion chamber is located is 60 degrees.

[0014] In yet another specific embodiment of the present invention, the height of the front wall of the cavity is 17 mm, and the length of the bottom wall of the cavity is 85 mm.

[0015] In one embodiment of the present invention, the through hole outlet of the fuel injection 13 is close to the front wall surface of the cavity 14; the fuel injection hole is a cylindrical hole with a hole diameter of 0.1-0.8 mm.

[0016] In another embodiment of the present invention, the plasma assisted ejector is composed of a premixing chamber 15 and a jet generating chamber 16, and the wall of the jet generating chamber 16 is made of conductive metal; the premixing chamber 15 is at the bottom and has a larger diameter, and is a cylindrical cavity, having a lower end face 17 and an upper end face 18-1; the jet generating chamber 16 is above the premixing chamber, and is composed of a cylindrical cavity and a central electrode located at the center of the cavity, and has a lower end face 18-2 and an upper end face 19; wherein the upper end face 18-1 of the premixing chamber and the lower end face 18-2 of the jet generating chamber are combined into a common end face 18; the premixing chamber cavity and the jet generating chamber cavity are connected through a circular small hole arranged on the common end face 18 between the two; an air inlet and a fuel inlet are arranged on the lower end face 17 of the premixing chamber 15; a jet nozzle is arranged on the upper end face 19 of the jet generating chamber 16 for injecting high-temperature combustion gas into the combustion chamber;

[0017] The central electrode of the plasma assisted ejector 12 is connected to the high voltage end of the power supply, and the wall surface of the jet generating chamber 16 is connected to the low voltage end of the power supply.

[0018] In another embodiment of the present invention, the circular holes are arranged on the common end surface 18 between the premixing chamber cavity and the jet generating chamber cavity, and the size and number of the circular holes are set according to the flow rate of the plasma-assisted ejector.

[0019] In another specific embodiment of the present invention, the fuel inlet has a circular cross section and is arranged at the center of the lower end surface 17 of the mixing chamber; the air inlet has a circular cross section and is arranged between the center and the edge of the lower end surface 17 of the mixing chamber; and the jet nozzle has a circular cross section.

[0020] In another specific embodiment of the present invention, the outer diameter of the premixing chamber is 22 mm, the outer diameter of the jet generating chamber is 10 mm; the fuel inlet diameter is 2 mm; and the air inlet diameter is 5 mm.

[0021] In addition, a method for regulating the working mode of a scramjet engine by using a plasma-assisted jet is provided. The method is based on the above-mentioned device for regulating the working mode of a scramjet engine by using a plasma-assisted jet, and specifically comprises the following steps:

[0022] Step 1: Install the plasma-assisted jet control engine mode device on the scramjet engine direct-connection test bench, select a nozzle with a suitable Mach number according to the flight state of the high-speed aircraft, and connect the nozzle to the plasma-assisted jet control engine mode device;

[0023] Step 2: Start the scramjet engine direct-connected test bench, and the supersonic airflow enters the plasma-assisted jet control engine mode device. The airflow passes through the isolation section 1, the combustion chamber 2 and the nozzle 3 in sequence and then is discharged into the atmosphere;

[0024] Step 3: The injection 13 in the concave cavity is turned on to inject fuel into the combustion chamber 2; the plasma-assisted ejector 12 is turned on, and the air between the central electrode and the wall of the jet generating chamber 16 is punctured by discharge to form plasma; the air and fuel enter the premixing chamber 15 from bottom to top through the air inlet and the fuel inlet of the premixing chamber respectively, and a mixed gas is formed in the premixing chamber 15. The mixed gas enters the jet generating chamber 16 through the circular small hole, and after plasma dissociation and ignition in the jet generating chamber 16, it is discharged to the combustion chamber through the jet nozzle to form a plasma-assisted jet; in the process of the plasma-assisted jet flowing downstream, the fuel injected from the concave cavity 14 is ignited, and the combustion chamber 2 works normally.

[0025] Step 4: The high back pressure caused by the combustion in the combustion chamber 2 propagates to the upstream flow field through the boundary layer, forming a shock wave train in the isolation section 1. The supersonic airflow is decelerated, pressurized, and heated after passing through the shock wave train; the pressurized and heated air is mixed with the fuel and burned in the combustion chamber 2, and then discharged into the atmosphere through the nozzle 3;

[0026] Step 5: When the incoming flow Mach number is low, the gas flow rate and equivalence ratio of the plasma-assisted ejector 12 are reduced, the fuel flow rate injected by the cavity 14 is increased, and the working mode of the scramjet engine is adjusted to the subcombustion mode;

[0027] Step 6: When the incoming flow Mach number is high, the gas flow rate and equivalence ratio of the plasma-assisted ejector 12 are increased, the fuel flow rate injected by the cavity 14 is reduced, and the working mode of the scramjet engine is adjusted to the scramjet mode.

[0028] A plasma-assisted jet method that can be used for scramjet engine operating mode control is used to actively regulate the scramjet engine operating mode at different flight Mach numbers to improve engine performance.

[0029] The advantages of the present invention are as follows:

[0030] (1) The plasma-assisted ejector of the present invention is used to control the working mode of a scramjet engine. The plasma-assisted ejector injected into the engine channel is a pre-combustion combustion gas, which can improve the combustion efficiency of the engine.

[0031] (2) The plasma-assisted ejector of the present invention is used to control the operating mode of a scramjet engine. It is fixed at the installation position of the scramjet engine, and can realize continuous adjustment of the engine operating mode while reducing the complexity of the mode adjustment mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention is a schematic diagram of a device for regulating the working mode of a scramjet engine using a plasma-assisted jet.

[0033] Figure 2 Schematic diagram of the plasma assisted ejector of the present invention. DETAILED DESCRIPTION

[0034] The present invention provides a device for regulating the working mode of a scramjet engine by using a plasma-assisted jet (referred to as "plasma-assisted jet engine mode regulating device").

[0035] like Figure 1 As shown in (b), the plasma-assisted jet control engine mode device is along the airflow direction, and the interior is a cavity (the following content is all about the internal cavity and related functional structures, which has nothing to do with the appearance of the device). The device consists of an isolation section 1, a combustion chamber 2, a nozzle 3, a plasma-assisted ejector 12, an injection 13, a cavity 14, etc. The cavity width of the entire device remains unchanged.

[0036] like Figure 1As shown in (a), the isolation section 1 adopts a uniform cross-section configuration, consisting of a left wall 4-1, a right wall 5-1, an upper wall 6 and a lower wall 7 (all inner walls). The ratio of the isolation section inlet height (the distance between the upper wall 6 and the lower wall 7 on the left side of the isolation section 1) to the inlet width (the distance between the left wall 4 and the right wall 5 of the isolation section 1) is less than 1. In a specific embodiment of the present invention, the ratio is 1:2, the isolation section outlet size is the same as the inlet size, and the isolation section upper wall 6 and the lower wall 7 are parallel to the horizontal plane.

[0037] The combustion chamber 2 is composed of a left wall 4-2, a right wall 5-2, an upper wall 8 and a lower wall 9, and is a unilateral expansion configuration. In a specific embodiment of the present invention, the expansion angle (the angle between the upper wall 8 and the lower wall 9) is 2 degrees. The left wall 4-2 of the combustion chamber is integrated and coplanar with the left wall 4-1 of the isolation section, the right wall 5-2 of the combustion chamber is integrated and coplanar with the right wall 5-1 of the isolation section, the upper wall 8 of the combustion chamber is integrated and coplanar with the upper wall 6 of the isolation section, and the lower wall 9 of the combustion chamber is integrated with the lower wall 7 of the isolation section, but the lower wall 9 of the combustion chamber expands downward at a certain angle, as described above. The inlet size of the combustion chamber 2 is the same as the outlet size of the isolation section 1. The combustion chamber includes a plasma-assisted ejector 12, a fuel injection 13, and a concave cavity 14, as follows.

[0038] The concave cavity 14 is roughly located in the middle of the combustion chamber 2, and is composed of a front wall, a rear wall and a bottom wall. The front wall of the concave cavity is perpendicular to the lower wall 9 of the combustion chamber, and the bottom wall of the concave cavity is parallel to the lower wall 9 of the combustion chamber. The rear wall of the concave cavity is a convergent configuration, and the angle between it and the plane where the lower wall 9 of the combustion chamber is located is 60 degrees. The concave cavity is a conventional technical means in this field, and its shape is a conventional shape. The ratio of the height of the front wall of the concave cavity to the length of the bottom wall of the concave cavity is less than 10. In a specific embodiment of the present invention, the height of the front wall of the concave cavity is 17 mm, and the length of the bottom wall of the concave cavity is 85 mm. The width of the concave cavity is the same as the width of the lower wall 9.

[0039] A fuel injection 13 is arranged on the bottom wall of the cavity. The fuel injection 13 is a through hole that penetrates the lower body of the plasma-assisted jet control engine mode device from bottom to top. The outlet of the through hole is located at the center between the left wall 4-2 and the right wall 5-2. Figure 1 In a specific embodiment of the present invention shown, the through hole outlet is slightly close to the front wall of the cavity 14. The fuel injection hole is usually a cylindrical hole with a hole diameter of preferably 0.1-0.8 mm, preferably 0.4 mm.

[0040] A plasma-assisted ejector 12 is installed upstream of the concave cavity 14, which includes a through hole that penetrates the lower body of the plasma-assisted jet control engine mode device from bottom to top and a plasma-assisted ejector fixedly installed in the through hole. The shape of the through hole is designed to adapt to the shape of the plasma-assisted ejector, and the plasma-assisted ejector 12 is at a certain distance from the front wall of the concave cavity. The plasma-assisted ejector is composed of a premixing chamber 15 and a jet generation chamber 16, and the wall of the jet generation chamber 16 is made of conductive metal. The premixing chamber 15 is at the bottom and has a larger diameter. It is a cylindrical cavity with a lower end face 17 and an upper end face 18-1. The jet generation chamber 16 is above the premixing chamber, and is composed of a cylindrical cavity and a central electrode located in the center of the cavity, and has a lower end face 18-2 and an upper end face 19. The upper end face 18-1 of the premixing chamber and the lower end face 18-2 of the jet generation chamber are combined into a common end face 18. The premixing chamber cavity is connected to the jet generating chamber cavity through a circular small hole arranged on the common end face 18 between the two (the size and number of the small holes are set according to the flow rate of the plasma-assisted ejector). An air inlet and a fuel inlet (both are through holes) are arranged on the lower end face 17 of the premixing chamber 15. The fuel inlet is usually a circular cross-section, and is usually arranged at the center of the lower end face 17 of the mixing chamber, for example, with a diameter of 2 mm. The air inlet is usually also a circular cross-section, and is usually arranged between the center and the edge of the mixing chamber end face 17, for example, with a diameter of 5 mm. A jet nozzle (a through hole) is arranged on the upper end face 19 of the jet generating chamber 16. The jet nozzle is usually a circular cross-section, which is used to spray high-temperature combustion gas into the combustion chamber.

[0041] The central electrode of the plasma-assisted ejector 12 is connected to the high-voltage end of the power supply, and the wall of the jet generation chamber 16 is connected to the low-voltage end of the power supply. When the power is turned on, the air between the central electrode and the wall of the jet generation chamber 16 is broken down by discharge to form plasma. Air and fuel enter the premixing chamber 15 from bottom to top through the air inlet and fuel inlet of the premixing chamber, respectively, and form a mixed gas in the premixing chamber 15. The mixed gas enters the jet generation chamber 16 through the circular small hole, and after plasma dissociation and ignition in the jet generation chamber, it is discharged to the combustion chamber through the jet nozzle 17 to form a plasma-assisted jet.

[0042] The nozzle 3 is composed of an upper wall 10, a lower wall 11, a left wall 4-3 and a right wall 5-3, and adopts a bilateral expansion configuration, and the expansion angle (the angle between the upper wall 10 of the nozzle and the upper wall 6 of the isolation section, and also the angle between the lower wall 11 of the nozzle and the lower wall 7 of the isolation section) is θ2. The nozzle inlet size is the same as the combustion chamber outlet size. The left wall 4-3 of the nozzle is integrated and coplanar with the left wall 4-2 of the combustion chamber, the right wall 5-3 of the nozzle is integrated and coplanar with the right wall 5-2 of the combustion chamber, the upper wall 10 of the nozzle is integrated with the upper wall 8 of the combustion chamber, but the upper wall 10 of the nozzle expands upward from the upper wall 8 of the combustion chamber by a certain angle, and the lower wall 11 of the nozzle is integrated with the lower wall 9 of the combustion chamber, but the lower wall 11 of the nozzle expands downward from the lower wall 9 of the combustion chamber by a certain angle.

[0043] The present invention also provides a method for regulating the operating mode of a scramjet engine by using a plasma-assisted jet, which specifically comprises the following steps:

[0044] Step 1: Install the plasma-assisted jet control engine modal device on the scramjet engine direct-connected test bench (Jia Min, Research on Sliding Arc Plasma Jet Ignition Technology for Scramjet Engines, 2021), select a nozzle with a suitable Mach number according to the flight state of the high-speed aircraft, and connect the nozzle to the plasma-assisted jet control engine modal device.

[0045] Step 2: Start the scramjet engine direct-connected test bench, and the supersonic airflow enters the plasma-assisted jet control engine mode device. The airflow passes through the isolation section 1, the combustion chamber 2 and the nozzle 3 and is discharged into the atmosphere.

[0046] Step 3: The injection 13 in the concave cavity is turned on to inject fuel into the combustion chamber 2; the plasma-assisted ejector 12 is turned on, and the air between the central electrode and the wall of the jet generating chamber 16 is punctured by discharge to form plasma; the air and fuel enter the premixing chamber 15 from bottom to top through the air inlet and the fuel inlet of the premixing chamber respectively, and a mixed gas is formed in the premixing chamber 15, and the mixed gas enters the jet generating chamber 16 through the circular small hole, and after plasma dissociation and ignition in the jet generating chamber 16, it is discharged to the combustion chamber through the jet nozzle 17 to form a plasma-assisted jet; in the process of the plasma-assisted jet flowing downstream, the fuel injected from the concave cavity 14 is ignited, and the combustion chamber 2 works normally.

[0047] Step 4: The high back pressure caused by the combustion in the combustion chamber 2 propagates to the upstream flow field through the boundary layer, forming a shock wave train in the isolation section 1. The supersonic airflow is decelerated, pressurized, and heated after passing through the shock wave train. The pressurized and heated air is mixed with the fuel and burned in the combustion chamber 2, and then discharged into the atmosphere through the nozzle 3.

[0048] Step 5: When the incoming flow Mach number is low, the gas flow rate and equivalence ratio of the plasma-assisted ejector 12 are reduced, the fuel flow rate injected into the cavity 14 is increased, and the operating mode of the scramjet engine is adjusted to the subcombustion mode.

[0049] Step 6: When the incoming flow Mach number is high, the gas flow rate and equivalence ratio of the plasma-assisted ejector 12 are increased, the fuel flow rate injected by the cavity 14 is reduced, and the working mode of the scramjet engine is adjusted to the scramjet mode.

Claims

1. A device for regulating the working mode of a scramjet engine by plasma-assisted jet, hereinafter referred to as "plasma-assisted jet regulating engine mode device", characterized in that: The device comprises an isolation section (1), a combustion chamber (2), a nozzle (3), a plasma auxiliary ejector (12), an injection (13), and a concave cavity (14); the cavity width of the entire device remains unchanged; in The isolation section (1) adopts a uniform cross-section configuration and is composed of an isolation section left wall surface (4-1), an isolation section right wall surface (5-1), an isolation section upper wall surface (6) and an isolation section lower wall surface (7); the ratio of the isolation section inlet height to the inlet width is less than 1, the isolation section outlet size is the same as the inlet size, and the isolation section upper wall surface (6) and the isolation section lower wall surface (7) are both parallel to the horizontal plane; The combustion chamber (2) is composed of a left combustion chamber wall (4-2), a right combustion chamber wall (5-2), an upper combustion chamber wall (8) and a lower combustion chamber wall (9), and is a single-sided expansion configuration with a certain expansion angle; the left combustion chamber wall (4-2) is integrated with the left wall (4-1) of the isolation section and is coplanar, the right combustion chamber wall (5-2) is integrated with the right wall (5-1) of the isolation section and is coplanar, the upper combustion chamber wall (8) is integrated with the upper wall (6) of the isolation section and is coplanar, and the lower combustion chamber wall (9) is integrated with the lower wall (7) of the isolation section, but the lower combustion chamber wall (9) expands downward at a certain angle; the inlet size of the combustion chamber (2) is the same as the outlet size of the isolation section (1); the combustion chamber is provided with a plasma auxiliary ejector (12), a fuel injection (13) and a concave cavity (14), as follows; The concave cavity (14) is approximately located in the middle of the combustion chamber (2), and is composed of a front wall, a rear wall and a bottom wall; the front wall of the concave cavity is perpendicular to the lower wall (9) of the combustion chamber, and the bottom wall of the concave cavity is parallel to the lower wall (9) of the combustion chamber; the rear wall of the concave cavity is a convergent configuration, and forms a certain angle with the plane where the lower wall (9) of the combustion chamber is located; the ratio of the height of the front wall of the concave cavity to the length of the bottom wall of the concave cavity is less than 10, and the width of the concave cavity is the same as the width of the lower wall (9) of the combustion chamber; A fuel injection (13) is arranged on the bottom wall of the concave cavity. The fuel injection (13) is a through hole that penetrates the body below the plasma-assisted jet control engine mode device from bottom to top, and the outlet of the through hole is located at the center between the left wall (4-2) and the right wall (5-2) of the combustion chamber. A plasma-assisted ejector (12) is installed upstream of the concave cavity (14), comprising a through hole penetrating from bottom to top through the body below the plasma-assisted ejector regulating engine mode device and a plasma-assisted ejector fixedly installed in the through hole, wherein the shape of the through hole is designed to adapt to the shape of the plasma-assisted ejector; the plasma-assisted ejector (12) is at a certain distance from the front wall of the concave cavity; The nozzle (3) is composed of a nozzle upper wall surface (10), a nozzle lower wall surface (11), a nozzle left wall surface (4-3) and a nozzle right wall surface (5-3), and adopts a bilateral expansion configuration with an expansion angle of θ2; the nozzle inlet size is the same as the combustion chamber outlet size; the nozzle left wall surface (4-3) and the combustion chamber left wall surface (4-2) are integrated and coplanar, the nozzle right wall surface (5-3) and the combustion chamber right wall surface (5-2) are integrated and coplanar, the nozzle upper wall surface (10) and the combustion chamber upper wall surface (8) are integrated, but the nozzle upper wall surface (10) expands upward from the combustion chamber upper wall surface (8) by a certain angle, and the nozzle lower wall surface (11) and the combustion chamber lower wall surface (9) are integrated, but the nozzle lower wall surface (11) expands downward from the combustion chamber lower wall surface (9) by a certain angle.

2. The device for controlling the operating mode of a scramjet engine by plasma-assisted jet according to claim 1, characterized in that: The ratio of the isolation section inlet height to the inlet width of the isolation section (1) is 1:2; and the expansion angle of the combustion chamber is 2 degrees.

3. The device for controlling the operating mode of a scramjet engine by plasma-assisted jet according to claim 1, characterized in that: The angle between the rear wall surface of the concave cavity and the plane where the lower wall surface (9) of the combustion chamber is located is 60 degrees.

4. The device for controlling the operating mode of a scramjet engine by plasma-assisted jet according to claim 1, characterized in that: The height of the front wall of the cavity is 17 mm, and the length of the bottom wall of the cavity is 85 mm.

5. The device for regulating the operating mode of a scramjet engine by plasma-assisted jet according to claim 1, characterized in that: The through hole outlet of the fuel injection (13) is close to the front wall surface of the cavity (14); the fuel injection hole is a cylindrical hole with a hole diameter of 0.1-0.8 mm.

6. The device for regulating the operating mode of a scramjet engine by plasma-assisted jet according to claim 1, characterized in that: The plasma-assisted ejector is composed of a premixing chamber (15) and a jet generating chamber (16), wherein the wall of the jet generating chamber (16) is made of conductive metal; the premixing chamber (15) is located at the bottom and has a larger diameter, and is a cylindrical cavity, and has a lower end surface (17) and an upper end surface (18-1); the jet generating chamber (16) is located above the premixing chamber, and is composed of a cylindrical cavity and a central electrode located at the center of the cavity, and has a lower end surface (18-2) and an upper end surface (19). ; wherein the upper end surface (18-1) of the premixing chamber and the lower end surface (18-2) of the jet generating chamber are combined into a common end surface (18); the cavity of the premixing chamber and the cavity of the jet generating chamber are connected through a circular small hole arranged on the common end surface (18) between the two; an air inlet and a fuel inlet are arranged on the lower end surface (17) of the premixing chamber (15); a jet nozzle is arranged on the upper end surface (19) of the jet generating chamber (16) for injecting high-temperature combustion gas into the combustion chamber; The central electrode of the plasma auxiliary jet device (12) is connected to the high voltage end of the power supply, and the wall surface of the jet generation chamber (16) is connected to the low voltage end of the power supply.

7. The device for regulating the operating mode of a scramjet engine by plasma-assisted jet according to claim 6, characterized in that: The circular small holes are arranged on the common end surface (18) between the premixing chamber cavity and the jet generating chamber cavity, and the size and number of the small circular holes are set according to the flow rate of the plasma-assisted ejector.

8. The device for regulating the operating mode of a scramjet engine by plasma-assisted jet according to claim 6, characterized in that: The fuel inlet has a circular cross section and is arranged at the center of the lower end surface (17) of the mixing chamber; the air inlet has a circular cross section and is arranged between the center and the edge of the lower end surface (17) of the mixing chamber; and the jet nozzle has a circular cross section.

9. The device for regulating the operating mode of a scramjet engine by plasma-assisted jet according to claim 8, characterized in that: The outer diameter of the premixing chamber is 22 mm, the outer diameter of the jet generating chamber is 10 mm; the fuel inlet diameter is 2 mm; and the air inlet diameter is 5 mm.

10. A method for regulating the operating mode of a scramjet engine by using a plasma-assisted jet, which is based on the device for regulating the operating mode of a scramjet engine by using a plasma-assisted jet as claimed in any one of claims 1 to 9, characterized in that: The specific steps include: Step 1: Install the plasma-assisted jet control engine mode device on the scramjet engine direct-connection test bench, select a nozzle with a suitable Mach number according to the flight state of the high-speed aircraft, and connect the nozzle to the plasma-assisted jet control engine mode device; Step 2: Start the scramjet engine direct-connected test bench, and the supersonic airflow enters the plasma-assisted jet control engine mode device, and the airflow passes through the isolation section (1), the combustion chamber (2) and the nozzle (3) in sequence and then is discharged into the atmosphere; Step 3: The injection (13) in the cavity is turned on to inject fuel into the combustion chamber (2); the plasma-assisted ejector (12) is turned on, and the air between the central electrode and the wall of the jet generation chamber (16) is punctured by discharge to form plasma; air and fuel enter the premixing chamber (15) from bottom to top through the air inlet and the fuel inlet of the premixing chamber, respectively, to form a mixed gas in the premixing chamber (15), and the mixed gas enters the jet generation chamber (16) through the circular small hole, and after being plasma-dissociated and ignited in the jet generation chamber (16), it is discharged to the combustion chamber through the jet nozzle to form a plasma-assisted jet; in the process of the plasma-assisted jet flowing downstream, the fuel injected from the cavity (14) is ignited, and the combustion chamber (2) operates normally; Step 4: The high back pressure caused by the combustion in the combustion chamber (2) propagates to the upstream flow field through the boundary layer, forming a shock wave train in the isolation section (1). The supersonic airflow is decelerated, pressurized, and heated after passing through the shock wave train; the pressurized and heated air is mixed with the fuel and burned in the combustion chamber (2), and then discharged into the atmosphere through the nozzle (3); Step 5: When the incoming flow Mach number is low, the gas flow rate and equivalence ratio of the plasma-assisted ejector (12) are reduced, the fuel flow rate injected by the cavity (14) is increased, and the operating mode of the scramjet engine is adjusted to a subcombustion mode; Step 6: When the incoming flow Mach number is high, the gas flow rate and equivalence ratio of the plasma-assisted ejector (12) are increased, the fuel flow rate injected by the cavity (14) is reduced, and the operating mode of the scramjet engine is adjusted to the scramjet mode.

Images