Natural-vibration same-frequency fuel pulse injection system and method for scramjet engine

Abstract

The invention provides a scramjet engine natural vibration co-frequency fuel pulse injection system and method, a fuel injection device and a self-adaptive opening and closing air inflow device.The fuel injection device comprises a driving device and a fuel conveying rotor shaft, and the output end of the driving device is fixedly connected with the fuel conveying rotor shaft; and the self-adaptive opening and closing air inlet device is communicated with an air inlet of the driving device. The method comprises the steps that 1, the air inlet channel starts to capture air; 2, the natural vibration frequency of an engine is obtained, and the natural vibration frequency information of the engine is fed back to a driving motor of the self-adaptive opening and closing air inlet device; 3, the driving motor drives the sealing piece set to act, and the opening degree of the corresponding rotating speed of the pneumatic motor is adjusted; 4, pulse frequency information of fuel injection is obtained; and 5, the preset program starts phase matching work, and finally the phase is adjusted to the phase where the fuel pulse injection wave crest and the natural vibration pressure signal wave crest are overlapped.

Description

Technical Field

[0001] The present invention relates to a scramjet engine self-oscillation same-frequency fuel pulse injection system and method, belonging to the technical field of internal combustion engines. Background Art

[0002] Supersonic vehicles powered by scramjets experience high airflow velocities and high total pressures at the inlet. As flight speed changes, the shock wave within the inlet cavity oscillates continuously at a constant frequency. This oscillation is divided into an upward shock wave pressurization phase and a downward shock wave decompression phase. For example, the paper "Experimental Study of Wave Evolution Under Scramjet Auto-Ignition Conditions" found that at a Mach number of Ma = 2.5, the cavity oscillation frequency is 143 Hz; the paper "Study of the Combustion Process in Ethylene-Fueled Scramjet Engines" found that at a flight Mach number of Ma = 4.0, the cavity oscillation frequency is 400 Hz. The downward shock wave decompression phase has a negligible effect on the generation of thrust. Currently, conventional scramjet fuel injection schemes continuously inject fuel during both the pressurization and decompression phases. This results in only approximately 50% effective fuel utilization during the upward shock wave compression phase within the scramjet cavity. Therefore, minimizing fuel injection during the downward shock wave decompression phase is crucial at the microscopic level.

[0003] To effectively utilize the shock wave uplift process and improve fuel utilization, researchers have previously developed a series of fuel pulse injection devices and technologies. For example, Chinese patent publication CN 116146352 B, "Scramjet Spanwise Non-uniform Fuel Pulse Injection Device and Method of Use," discloses a pulse injection device that generates fuel pulse signals based on the motion of a piezoelectric crystal; CN 110863925 B, "Hypersonic Mechanically Driven Frequency-Modulated Pulse Injection Device and Method," discloses a pulse injection device that generates fuel pulse signals using piston motion; and CN 112879177 B, "Hypersonic Mechanically Driven Gas-Liquid Dual-Purpose Pulse Injection Device and Method," discloses a pulse injection device that can be used with both gaseous and liquid hydrocarbon fuels, generating fuel pulse signals through dual-cylinder compression. However, these pulse injection devices and technologies do not consider the coordination of the pulse injection frequency with the scramjet's natural frequency. Instead, they all enhance fuel mixing efficiency and thus improve fuel utilization by increasing the penetration depth of the fuel injection or instantaneously increasing the injection pressure to enhance atomization.

[0004] In summary, it is urgent to develop a method for using scramjet self-oscillation and synchronous combustion based on the fuel pulse injection device by utilizing the frequency characteristics of the pulse injection device and combining it with the oscillation frequency characteristics of the scramjet engine itself during operation. Summary of the Invention

[0005] Purpose of the invention: In view of the deficiencies in the prior art, the present invention provides a scramjet engine self-oscillating same-frequency fuel pulse injection system and method to solve the problems mentioned in the above background technology.

[0006] Technical solution: A scramjet engine self-oscillating synchronous frequency fuel pulse injection system includes at least two fuel injection devices arranged in an array along the periphery of an intake duct and an adaptive opening and closing intake device. The fuel injection devices are arranged through the intake duct and fixedly mounted on the outside of the intake duct via flanges. The adaptive opening and closing intake device communicates with the intake duct via an intake channel of the device.

[0007] The fuel injection device includes a driving device based on a pneumatic motor as a power source and a fuel delivery rotor shaft with a hollow interior and openings on both sides. The output end of the driving device is fixedly connected to the fuel delivery rotor shaft, and the adaptive opening and closing air intake device is connected to the air inlet of the driving device.

[0008] The openings on both sides of the fuel delivery rotor shaft are symmetrically arranged, the openings correspond to the positions of the fuel input ports, and the lower ends penetrate the wall of the intake pipe and are connected to the intake pipe. Periodic fuel injection is achieved by rotating the fuel delivery rotor shaft.

[0009] The present invention is a self-oscillating, same-frequency fuel pulse injection device for a scramjet engine, which is assembled by conventional servo motors and pneumatic motors currently available on the market. The required driving gas can be provided by the incoming gas captured by the aircraft. It can work without the need for a power supply and an electric motor, thus reducing the burden on the aircraft's power supply system.

[0010] The adaptive opening and closing air intake device includes a fixed base, the upper portion of the fixed base is configured as a bent plate structure, a drive motor is provided on the outer side of the bent plate, and the output end of the drive motor extends toward the base plate and is fixedly connected to a drive gear;

[0011] The lower part of the fixed base is provided with an air inlet opening control mechanism, which includes a circular fixed rotatable base fixedly connected to the fixed base, a hollow rotating cover sleeved on the outer periphery of the fixed rotatable base and provided with meshing teeth on the edge, and a sealing plate assembly installed between the inside of the rotating cover and the fixed rotatable base;

[0012] The fixed rotating base has an opening in the middle, and a horizontal slide groove distributed in a circular array is provided around the opening. The sealing piece group includes sealing piece monomers that match the number of slide grooves. Any sealing piece monomer includes a sealing piece body. The sealing piece body is provided with a slider embedded in the slide groove on one side close to the slide groove, and a column connected to the rotating cover is provided on the other side. A short groove is provided on the rotating cover corresponding to the position of the column. The column passes through the short groove and is slidably connected to the rotating cover. A retaining spring disk is fixedly connected to the outside of the rotating cover. The retaining spring disk extends away from the driving gear side in the direction of the fixed base, and is provided with a retaining spring piece that passes through the rotating sealing disk. The retaining spring piece abuts against the ball bearing provided on the outer periphery of the fixed rotating base to achieve smooth rotation while limiting the upper and lower positions.

[0013] In order to achieve precise control of the air intake volume of the device's air intake, a driving motor is set to drive the sealing plate to move in conjunction, thereby realizing the contraction and dispersion of the sealing plate to change the opening area of ​​the air intake channel, and further control the rotation speed of the driving device, thereby changing the pulse frequency of the fuel injection and changing the combustion pressure value of the combustion chamber.

[0014] There are 6 chutes, which are not connected to each other, and their extended lines intersect to form an equilateral hexagonal structure; the sealing plate group includes 6 sealing plate monomers, and any sealing plate monomer is set to an isosceles trapezoidal structure. The slider and the column position correspond to each other up and down, and are both set on the side close to the sealing plate monomer and parallel to the waistline. Driven by the rotating cover, the sealing plate monomer moves along the chute, driving each sealing plate monomer of the sealing plate group to rotate inward, and finally realizing the closure of the air inlet channel of the device.

[0015] The fuel injection devices are evenly arranged in an circumferential direction along the injection panel of the scramjet engine in eight numbers.

[0016] Control method for scramjet self-oscillation co-frequency fuel pulse injection system,

[0017] Step 1: The scramjet engine on board the aircraft starts, the air intake begins to capture air, the fuel injection device starts to spray fuel, and the fuel is fully mixed with the intake air and ignited in the combustion chamber;

[0018] Step 2: A preset program determines the engine's natural frequency by reading a pressure signal fed back by a wall pressure sensor within the scramjet engine, and feeds the engine's natural frequency information back to the drive motor of the adaptive opening and closing air intake device;

[0019] Step 3: The driving motor drives the rotating cover in the adaptive opening and closing air intake device, drives the sealing plate group to move, and adjusts the opening to the corresponding speed of the pneumatic motor. The corresponding relationship is

[0020] Intermediate speed / maximum speed = intake area / maximum intake area;

[0021] Step 4: The preset program reads the pulse oscillation pressure signal during the fuel injection process from the pressure sensor at the fuel injection port of the scramjet engine to obtain the pulse frequency information of the fuel injection;

[0022] Step 5: The preset program starts phase matching. The combustion pressure value fed back by the wall pressure sensor in the scramjet engine is used to determine whether the combustion performance has improved. By repeating steps 2 and 1, the phase is finally adjusted to the phase where the peak of the fuel pulse injection wave overlaps with the peak of the natural oscillation pressure signal.

[0023] Specifically, step 1 comprises: starting the scramjet engine carried by the aircraft, and the air intake duct begins to capture air, and air is taken in through the air intake passage of the device. In the initial state, the adaptive opening and closing air intake device is fully opened, and the air sucked in by the opening and closing air intake is delivered to the driving device. The pneumatic motor in the driving device starts to rotate, driving the fuel delivery rotor shaft to rotate. The fuel alternately enters the hollow cavity of the fuel delivery rotor shaft through the openings on both sides of the fuel delivery rotor shaft, and is then ejected into the air intake duct, mixed with the air, and ignited in the combustion chamber.

[0024] The step 2 specifically includes: obtaining the engine natural frequency by fast Fourier transforming the pressure signal, i.e., the combustion pressure value.

[0025] Specifically, step 3 comprises the following steps: the drive motor and the rotating cover are driven by gears, the drive motor is initially set to 0 degrees, and the preset program automatically adjusts the angle to 0 degrees each time it is used, i.e., the maximum opening. For every 1 degree the drive motor rotates, the control panel also rotates 1 degree accordingly, and all are closed when the drive motor rotates 90 degrees.

[0026] The relationship between the driving motor rotation angle and the opening area:

[0027]

[0028] Where S is the current opening area, a is the side length of the hexagon formed when the opening is maximum, that is, the length of the inner edge of a single sealing piece, and β is the rotation angle of the drive motor.

[0029] Specifically, step 5 includes adjusting the opening and closing size of the air inlet by a preset program so that the rotation rate of the pneumatic motor is equal to half the natural frequency of the scramjet engine. Each rotation of the pneumatic motor drives the fuel delivery rotor shaft to rotate one circle. A pulse frequency twice the rotation rate is generated through the two openings of the fuel delivery rotor shaft, thereby making the frequency of the fuel pulse injection consistent with the natural frequency of the scramjet engine. At the same time, by continuously adjusting the rotation speed, the peak of the pulse injection is matched with the peak phase of the cavity oscillation, thereby achieving the purpose of generating periodic explosive thrust.

[0030] Beneficial effects: The present invention is a scramjet engine self-oscillation and same-frequency fuel pulse injection device formed by assembling conventional drive motors and pneumatic motors currently available on the market. The required driving gas can be provided by the incoming gas captured by the aircraft. It can work without configuring a power supply and an electric motor, thereby reducing the burden on the aircraft's power supply system. A scramjet engine self-oscillation and same-frequency fuel pulse injection system and method are formed by reasonably arranging and using the device. It can save fuel and stop injecting fuel during the decompression process of the downward shock wave in the engine, thereby achieving the purpose of improving fuel saving, reducing the amount of fuel carried by the aircraft, and reducing the aircraft's take-off weight. In addition, the method can also be used to add fuel during the pressurization process of the upward shock wave. By operating the device at the same vibration frequency and phase as the scramjet engine, periodic explosive thrust is generated at the microscopic level, further improving the thrust performance of the scramjet engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0032] Figure 1 This is a schematic diagram of the installation positions of the fuel injection device and the adaptive opening and closing air intake device of the present invention.

[0033] Figure 2 It is a cross-sectional view of the fuel injection device of the present invention.

[0034] Figure 3 This is the overall structural diagram of the adaptive opening and closing air intake device of the present invention.

[0035] Figure 4 This is a structural diagram of the fixed and rotating base of the present invention.

[0036] Figure 5 This is a structural diagram of the fixed rotating base and sealing plate assembly of the present invention.

[0037] Figure 6 This is a structural diagram of the sealing sheet of the present invention.

[0038] Figure 7 This is a structural diagram of the rotary cover of the present invention.

[0039] Figure 8 This is a structural diagram of the rotary cover, the retaining spring disk, the retaining spring sheet, the fixed rotating base and the sealing sheet assembly after assembly.

[0040] Figure 9 This is a flow chart of the intake control method of the present invention.

[0041] Figure 10 This is a cross-sectional view of a scramjet engine test model of the present invention.

[0042] Figure 11 This is a graph showing the pressure change over time at a single point in the middle and rear part of the cavity (x=575mm) under steady injection conditions in an embodiment of the present invention.

[0043] Figure 12 This is a graph showing the change in pressure over time at a single point in the middle and rear part of the cavity (x=575mm) under the condition of an injection frequency of 41 Hz in an embodiment of the present invention.

[0044] Figure 13 This is a graph showing the change in pressure over time at a single point in the middle and rear part of the cavity (x=575mm) under the condition of an injection frequency of 110 Hz in an embodiment of the present invention.

[0045] Figure 14 This is a graph showing the change in pressure over time at a single point in the middle and rear part of the cavity (x=575mm) under the condition of an injection frequency of 147Hz in an embodiment of the present invention.

[0046] Figure 15 This is a graph showing the change in pressure over time at a single point in the middle and rear part of the cavity (x=575mm) under the condition of an injection frequency of 210Hz in an embodiment of the present invention.

[0047] Figure 16 : This is the wall pressure curve along the top of the scramjet engine in an embodiment of the present invention.

[0048] Figure 17 Graph showing the coordinated relationship between the cavity natural frequency and the pulse injection frequency in an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0050] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0051] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0052] like Figures 1 to 8 As shown, a scramjet engine self-oscillating synchronous frequency fuel pulse injection system includes at least two fuel injection devices 1 and an adaptive opening and closing air intake device 2 distributed in an array along the air intake duct. The fuel injection device 1 is arranged to penetrate the air intake duct and is fixedly mounted on the outside of the air intake duct via a flange. The adaptive opening and closing air intake device 2 is connected to the air intake duct through the device air intake channel 3.

[0053] The fuel injection device 1 includes a driving device 11 powered by a pneumatic motor and a fuel delivery rotor shaft 12 with a hollow interior and openings on both sides. The output end of the driving device 11 is fixedly connected to the fuel delivery rotor shaft 12, and the adaptive opening and closing air intake device 2 is connected to the air inlet of the driving device 11.

[0054] The openings on both sides of the fuel delivery rotor shaft 12 are symmetrically arranged, and the openings correspond to the positions of the fuel input ports. The lower ends penetrate the wall of the intake pipe and are connected to the intake pipe. Periodic fuel injection is achieved by rotating the fuel delivery rotor shaft 12.

[0055] The present invention is a scramjet engine self-oscillating same-frequency fuel pulse injection device formed by assembling a conventional drive motor 22 and a pneumatic motor available on the market. The required driving gas can be provided by the incoming gas captured by the aircraft. It can work without the configuration of power supply and electric motor, which reduces the burden on the aircraft power supply system. The drive motor 22 uses a servo motor that can achieve precise control.

[0056] The adaptive opening and closing air intake device 2 includes a fixed base 21, the upper portion of the fixed base 21 is configured as a bent plate structure, a drive motor 22 is provided on the outer side of the bent plate, and the output end of the drive motor 22 extends toward the fixed base 21 and is fixedly connected to a drive gear 23;

[0057] The lower part of the fixed base 21 is provided with an air inlet opening control mechanism, which includes a circular fixed rotatable base 24 fixedly connected to the fixed base 21, a hollow rotating cover 25 sleeved on the outer periphery of the fixed rotatable base 24 and provided with meshing teeth on the edge, and a sealing plate assembly installed between the inside of the rotating cover 25 and the fixed rotatable base 24;

[0058] The fixed rotating base 24 has an opening in the middle, and a horizontal slide groove 26 distributed in a circumferential array is provided around the opening. The sealing plate group includes sealing plate monomers that match the number of slide grooves 26. Any sealing plate monomer includes a sealing plate body 27. The sealing plate body 27 is provided with a slider 28 embedded in the slide groove 26 on one side close to the slide groove 26, and a column 29 connected to the rotating cover 25 on the other side. A short groove 30 is provided on the rotating cover 25 corresponding to the position of the column 29. The column 29 passes through the short groove 30 and is slidably connected to the rotating cover 25. A retaining spring disk 31 is fixedly connected to the outside of the rotating cover 25. The retaining spring disk 31 extends away from the side of the driving gear 23 toward the fixed base 21, and is provided with a retaining spring piece 32 that passes through the rotating sealing disk. The retaining spring piece 32 abuts against the ball bearing provided on the outer periphery of the fixed rotating base 24 to achieve smooth rotation while limiting the upper and lower positions.

[0059] In order to achieve precise control of the air intake volume of the device's air inlet, a driving motor 22 is set to drive the sealing plate to move in conjunction, thereby realizing the contraction and dispersion of the sealing plate to change the opening area of ​​the air intake channel, and further controlling the rotation speed of the driving device 11, thereby changing the pulse frequency of the fuel injection and changing the combustion pressure value of the combustion chamber.

[0060] The slide grooves 26 are set to 6, and the slide grooves 26 are not connected to each other. Their extended lines intersect to form an equilateral hexagonal structure; the sealing plate group includes 6 sealing plate monomers, and any sealing plate monomer is set to an isosceles trapezoidal structure. The slider 28 and the column 29 are positioned correspondingly up and down, and are both set close to the side of the sealing plate monomer and parallel to the waistline. Driven by the rotating cover 25, the sealing plate monomer moves along the slide groove 26, driving each sealing plate monomer of the sealing plate group to rotate inward, and finally realizing the closure of the air inlet channel 3 of the device.

[0061] The fuel injection devices 1 are evenly arranged in eight circumferential directions along the injection panel of the scramjet engine.

[0062] like Figure 9 As shown in FIG, the control method of the scramjet engine self-oscillation same frequency fuel pulse injection system is

[0063] Step 1: The scramjet engine carried by the aircraft is started, the air intake begins to capture air, the fuel injection device 1 is started, and fuel is sprayed. The fuel is fully mixed with the intake air and ignited in the combustion chamber;

[0064] Step 2: The preset program determines the engine's natural frequency by reading the pressure signal fed back by the wall pressure sensor within the scramjet engine, and feeds the engine's natural frequency information back to the drive motor 22 of the adaptive opening and closing air intake device 2;

[0065] Step 3: The driving motor 22 drives the rotating cover 25 in the adaptive opening and closing air intake device 2, drives the sealing plate group to move, and adjusts the opening to the corresponding speed of the pneumatic motor. The corresponding relationship is:

[0066] Intermediate speed / maximum speed = intake area / maximum intake area;

[0067] Step 4: The preset program reads the pulse oscillation pressure signal during the fuel injection process from the pressure sensor at the fuel injection port of the scramjet engine to obtain the pulse frequency information of the fuel injection;

[0068] Step 5: The preset program starts phase matching. The combustion pressure value fed back by the wall pressure sensor in the scramjet engine is used to determine whether the combustion performance has improved. By repeating steps 2 and 1, the phase is finally adjusted to the phase where the peak of the fuel pulse injection wave overlaps with the peak of the natural oscillation pressure signal.

[0069] Specifically, step 1 comprises the following steps: the scramjet engine carried by the aircraft is started, the air intake begins to capture air, and air is taken in through the air intake passage 3 of the device. In the initial state, the adaptive opening and closing air intake device 2 is fully opened, and the air sucked in by the opening and closing air intake is delivered to the driving device 11. The pneumatic motor in the driving device 11 starts to rotate, driving the fuel delivery rotor shaft 12 to rotate. The fuel alternately enters the hollow cavity of the fuel delivery rotor shaft 12 through the openings on both sides of the fuel delivery rotor shaft 12, and is then ejected into the air intake pipe, mixed with the air, and ignited in the combustion chamber.

[0070] Specifically, step 2 includes: obtaining the engine's natural frequency through fast Fourier transform of the pressure signal, i.e., the combustion pressure value; the main function of the Fourier transform is to decompose any type of periodically changing function curve (i.e., the curve of pressure changing with time) into multiple periodically changing sine or cosine function curves in the time domain; the one with the largest amplitude among these sine or cosine function curves is the main frequency of oscillation, i.e., the natural frequency.

[0071] Specifically, step 3 is as follows: the drive motor 22 and the rotating cover 25 are driven by gears. The initial state of the drive motor 22 is 0 degrees. The preset program automatically adjusts the angle to 0 degrees each time it is used, that is, the maximum opening. When the drive motor 22 rotates 1 degree, the control panel also rotates 1 degree accordingly. When it reaches 90 degrees, it is completely closed.

[0072] The relationship between the rotation angle of the drive motor 22 and the opening area is:

[0073]

[0074] Where S is the current opening area, a is the side length of the hexagon formed when the opening is maximum, that is, the length of the inner edge of a single sealing piece, and β is the rotation angle of the drive motor 22.

[0075] Specifically, step 5 includes adjusting the opening and closing size of the air inlet by a preset program so that the rotation rate of the pneumatic motor is equal to half of the natural frequency of the scramjet engine. Each rotation of the pneumatic motor drives the fuel delivery rotor shaft 12 to rotate one circle. The two openings of the fuel delivery rotor shaft 12 can generate a pulse frequency twice the rotation rate, thereby making the frequency of the fuel pulse injection consistent with the natural frequency of the scramjet engine. At the same time, by continuously adjusting the rotation speed, the peak of the pulse injection is matched with the peak phase of the cavity oscillation, thereby achieving the purpose of generating periodic explosive thrust.

[0076] In order to verify the accuracy and feasibility of this scheme, parameters are set for experimental verification;

[0077] Example: Figure 10 As shown in the figure, relevant onboard tests were carried out on a rectangular cross-section scramjet engine with an inlet of 30×150. The Mach number at the inlet of the isolation section was 3.0, the total temperature of the incoming flow was 1920K, and the total pressure was 2.92MPa, corresponding to the flight Mach number of 7.0. The test measured the natural frequency of the cavity under this flight condition to be 147Hz.

[0078] like Figures 11 to 16 As shown in the figure, when the fuel injection driving pressure is fixed at 2.5 MPa, the combustion pressure in the cavity is generally between 0.13 and 0.14 MPa when the pulse injection frequency is adjusted to three typical operating conditions: 41 Hz, 110 Hz, and 210 Hz, which is lower than the 0.16 MPa of steady injection. When the pulse injection frequency is adjusted to match the engine's natural frequency, the combustion pressure in the cavity rises to 0.23 MPa, far higher than that of steady injection, resulting in a significant performance improvement.

[0079] like Figure 17 As shown in the figure, by placing all the wall pressure data of several groups of tests in the same coordinate system, it can be found that under the conditions where the pulse injection and the engine natural frequency are both 147 Hz, the wall pressure along the process is significantly higher than that under other conditions, which also confirms the above results.

[0080] At the same time, in order to fully determine the phase synergy relationship, Figure 8 The corresponding relationship between the wall pressure signal and the pulse signal at a pulse injection frequency of 147 Hz is shown. It is not difficult to find that although there are some errors, the peaks of most oscillation curves correspond to the peaks of the pulse injection signal one by one.

[0081] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0082] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A scramjet self-oscillating, same-frequency fuel pulse injection system, characterized by: The invention comprises at least two fuel injection devices (1) and an adaptive opening and closing air intake device (2) distributed in an array along an air intake pipe, wherein the fuel injection device (1) is arranged to penetrate the air intake pipe and is fixedly mounted on the outside of the air intake pipe via a flange, and the adaptive opening and closing air intake device (2) is connected to the air intake pipe via an air intake channel (3) of the device; The fuel injection device (1) comprises a driving device (11) powered by a pneumatic motor and a fuel delivery rotor shaft (12) having a hollow interior and openings on both sides. The output end of the driving device (11) is fixedly connected to the fuel delivery rotor shaft (12), and the adaptive opening and closing air intake device (2) is connected to the air intake of the driving device (11). The openings on both sides of the fuel delivery rotor shaft (12) are symmetrically arranged, the openings corresponding to the positions of the fuel input ports, and the lower ends penetrate the wall of the air intake pipe and are connected to the air intake pipe, so that periodic fuel injection is achieved by rotating the fuel delivery rotor shaft (12).

2. The scramjet self-oscillating, same-frequency fuel pulse injection system according to claim 1, characterized in that: The adaptive opening and closing air intake device (2) comprises a fixed base (21), the upper portion of the fixed base (21) is configured as a bent plate structure, a drive motor (22) is provided on the outer side of the bent plate, and an output end of the drive motor (22) extends toward the fixed base (21) and is fixedly connected to a drive gear (23); The lower portion of the fixed base (21) is provided with an air inlet opening control mechanism, comprising a circular fixed rotatable base (24) fixedly connected to the fixed base (21), a hollow rotating cover (25) sleeved on the outer periphery of the fixed rotatable base (24) and provided with meshing teeth on the edge thereof, and a sealing sheet assembly installed between the interior of the rotating cover (25) and the fixed rotatable base (24); The fixed rotating base (24) has an opening in the middle, and a horizontal slide groove (26) is provided around the opening in a circular array. The sealing piece group includes sealing piece monomers that match the number of the slide grooves (26). Any sealing piece monomer includes a sealing piece body (27). The sealing piece body (27) is provided with a slider (28) embedded in the slide groove (26) on one side close to the slide groove (26), and a column (29) connected to the rotating cover (25) is provided on the other side. The rotating cover (25) is located at a position corresponding to the column (29). A short slot (30) is provided at a corresponding position, and the column (29) passes through the short slot (30) and is slidably connected to the rotating cover (25). A retaining spring disk (31) is fixedly connected to the outer side of the rotating cover (25). The retaining spring disk (31) is extended in the direction of the fixed base (21) away from the side of the driving gear (23) and is provided with a retaining spring piece (32) passing through the rotating cover. The retaining spring piece (32) abuts against a ball provided on the outer periphery of the fixed rotating base (24), thereby achieving smooth rotation and limiting the upper and lower positions.

3. The scramjet self-oscillating, same-frequency fuel pulse injection system according to claim 2, characterized in that: The chute (26) is set to 6, and the chute (26) is not connected to each other. The extended lines of the chute (26) intersect to form an equilateral hexagonal structure; the sealing plate group includes 6 sealing plate monomers, and any sealing plate monomer is set to an isosceles trapezoidal structure. The slider (28) and the column (29) are positioned correspondingly up and down, and are both set close to the side of the sealing plate monomer and parallel to the waistline. Driven by the rotating cover (25), the sealing plate monomer moves along the chute (26), driving each sealing plate monomer of the sealing plate group to rotate inward, and finally achieving the closure of the device air inlet channel (3).

4. The scramjet self-oscillating, co-frequency fuel pulse injection system according to claim 1, characterized in that: The fuel injection devices (1) are evenly arranged in an circumferential direction along the injection panel of the scramjet engine in eight pieces.

5. The control method of the scramjet engine self-oscillation same-frequency fuel pulse injection system according to claim 1 is characterized by: Step 1: The scramjet engine carried by the aircraft is started, the air intake begins to capture air, the fuel injection device (1) is started, and the fuel is sprayed out. The fuel is fully mixed with the intake air and ignited in the combustion chamber; Step 2: The preset program determines the engine's natural frequency by reading the pressure signal fed back by the wall pressure sensor in the scramjet engine, and feeds back the engine's natural frequency information to the drive motor (22) of the adaptive opening and closing air intake device (2); Step 3: The driving motor (22) drives the rotating cover (25) in the adaptive opening and closing air intake device (2), drives the sealing plate group to move, and adjusts the opening to the corresponding speed of the pneumatic motor. The corresponding relationship is Intermediate speed / maximum speed = intake area / maximum intake area; Step 4: The preset program reads the pulse oscillation pressure signal during the fuel injection process from the pressure sensor at the fuel injection port of the scramjet engine to obtain the pulse frequency information of the fuel injection; Step 5: The preset program starts phase matching. The combustion pressure value fed back by the wall pressure sensor in the scramjet engine is used to determine whether the combustion performance has improved. By repeating steps 2 and 1, the phase is finally adjusted to the phase where the peak of the fuel pulse injection wave overlaps with the peak of the natural oscillation pressure signal.

6. The control method of the scramjet engine self-oscillation same-frequency fuel pulse injection system according to claim 5 is characterized by: The step 1 is specifically as follows: the scramjet engine carried by the aircraft is started, the air intake begins to capture air, and the air intake passage (3) of the device takes in air. In the initial state, the adaptive opening and closing air intake device (2) is fully opened, and the air sucked in by the opening and closing air intake is transported to the driving device (11). The pneumatic motor in the driving device (11) starts to rotate to drive the fuel delivery rotor shaft (12) to rotate, and the fuel alternately enters the hollow cavity of the fuel delivery rotor shaft (12) through the openings on both sides of the fuel delivery rotor shaft (12), and is then ejected into the air intake pipe, mixed with the air, and ignited in the combustion chamber.

7. The control method of the scramjet engine self-oscillation same-frequency fuel pulse injection system according to claim 5, characterized in that: The step 2 specifically includes: obtaining the engine natural frequency by fast Fourier transforming the pressure signal, i.e., the combustion pressure value.

8. The control method of the scramjet engine self-oscillation same-frequency fuel pulse injection system according to claim 5, characterized in that: Specifically, step 3 comprises: a gear transmission is provided between the driving motor (22) and the rotating cover (25); the driving motor (22) is initially at 0 degrees, and the preset program automatically adjusts the angle to 0 degrees each time it is used, i.e., the maximum opening; each time the driving motor (22) rotates 1 degree, the control panel also rotates 1 degree accordingly, and when the cover is 90 degrees, it is completely closed; The relationship between the rotation angle of the driving motor (22) and the opening area is: Where S is the current opening area, a is the side length of the hexagon formed when the opening is maximum, that is, the length of the inner edge of a single sealing piece, and β is the rotation angle of the drive motor (22).

9. The control method of the scramjet engine self-oscillation same-frequency fuel pulse injection system according to claim 5, characterized in that: Specifically, the step 5 is to adjust the opening and closing size of the opening and closing air inlet by a preset program so that the rotation rate of the air motor is equal to half of the natural frequency of the scramjet engine. Each time the air motor rotates one circle, the fuel delivery rotor shaft (12) is driven to rotate one circle. A pulse frequency twice the rotation rate can be generated through the two openings of the fuel delivery rotor shaft (12), thereby making the frequency of the fuel pulse injection consistent with the natural frequency of the scramjet engine. At the same time, by continuously adjusting the rotation speed, the peak of the pulse injection is matched with the peak phase of the cavity oscillation, thereby achieving the purpose of generating periodic explosive thrust.

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