An adjustable geometric throat with vector control for an axisymmetric rocket ramjet combination engine

Abstract

The invention discloses an adjustable geometric throat with vector adjustment for an axisymmetric rocket ramjet combination engine, comprising an axisymmetric combination engine combustion chamber casing, four through holes are arranged in a circle around the outer circumference of the geometric throat section of the combustion chamber casing, and the four through holes are located at the upper, lower, left and right sides of the geometric throat casing; each through hole is covered with a casing protruding outward, and a rectangular parallelepiped cavity connected to the geometric throat is formed in the casing; a slider is arranged in each cavity, and the front end of each slider extends into the geometric throat, and each slider can slide toward or away from the geometric throat in each cavity; two groups of sliders can slide toward the geometric throat at the same time to change the throat area; each group of sliders can slide toward the geometric throat independently to realize vector control of the engine. The area of ​​the combustion chamber of the axisymmetric RBCC engine is adjusted by driving the four sliders to realize efficient operation of different engines under different incoming flow conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of axisymmetric rocket-based combined cycle engines, and in particular relates to an adjustable geometric throat with vector regulation for an axisymmetric rocket ramjet combined engine. Background Art

[0002] The rocket-based combined-cycle (RBCC) engine is a combined propulsion system that organically integrates a rocket engine with a high thrust-to-weight ratio and low specific impulse and a ramjet engine with a low thrust-to-weight ratio and high specific impulse. The RBCC engine integrates the ejection mode, subsonic mode, scramjet mode and pure rocket mode, which makes the RBCC engine self-starting, has a wide flight envelope, and has strong mission adaptability, becoming one of the most promising new power devices in the future. The combustion chamber / tail nozzle is an important component in the engine. For an air-breathing engine, the combustion chamber is required to enable the fuel to be injected, atomized, evaporated, mixed and burned in the high-speed airflow in the combustion chamber within a limited space and time, and to convert chemical energy into heat energy to the maximum extent, and then convert the heat energy into kinetic energy to the maximum extent through the tail nozzle, thereby generating thrust. In the scramjet mode, in order to meet the needs of supersonic combustion, the combustion chamber flow channel needs to maintain an expansion structure; while in the ejection and sub-combustion modes, the combustion chamber flow channel can adopt a convergence and expansion structure to meet the high-efficiency combustion of the combustion chamber. At the same time, as the flight Mach number increases, the heating ratio in the combustion chamber gradually decreases, and the combustion chamber expansion ratio needs to be reduced accordingly to meet the high performance at different flight Mach numbers. Under the premise that multiple modes share a flow channel, engine variable structure technology is one of the effective ways to ensure that it achieves the best working performance throughout the process. At present, the engines using variable structure combustion chambers include dual-mode ramjet engines, such as the French WRR (wide-range ramjet) engine, which has a wide range of variable combustion chamber profiles to meet the high performance within the entire Mach number range (AIAA Paper 2000-3340, 2000); the PIAF engine chooses to use the horizontal movement of the outer cover to change the geometric structure of the combustion chamber to achieve a wide range of combustion chamber operation (AIAA Paper 2003-7031, 2003). For RBCC engines, variable structure solutions are only applied to intake and exhaust components. Aerojet of the United States proposed a simple variable structure RBCC engine solution for the intake duct and tail nozzle for single stage to orbit (SSTO) (NASA Technical Memorandum 107422) to ensure multi-mode coordinated and efficient operation. In the field of aero engines, the axisymmetric vector nozzle of an aero engine mainly relies on the adjustment ring to achieve vector control, and only adjusts the deflection of the expansion section to change the direction. At present, there are few studies on variable structure combustion chamber solutions for axisymmetric RBCC engines. Research on axisymmetric RBCC variable structure solutions and adjustable geometric throat configurations is extremely important for improving its engine performance. Summary of the invention

[0003] The purpose of the present invention is to provide an adjustable geometric throat with vector regulation for an axisymmetric rocket ramjet combination engine, which can adjust the area of ​​the axisymmetric RBCC engine combustion chamber by driving four sliders to achieve efficient operation of different engines under different incoming flow conditions.

[0004] The present invention adopts the following technical scheme: an adjustable geometric throat with vector adjustment for an axisymmetric rocket ramjet combination engine, characterized in that it includes an axisymmetric combination engine combustion chamber casing, four through holes are arranged in a circle around the outer circumference of the geometric throat section of the combustion chamber casing, and the four through holes are located at the upper, lower, left and right sides of the geometric throat casing; each through hole is covered with a casing protruding outward, and a rectangular concave cavity connected to the geometric throat is formed in the casing;

[0005] A slider is arranged in each cavity, which are an upper vertical slider, a lower vertical slider, a left horizontal slider and a right horizontal slider; the front end of each slider extends into the geometric throat, and each slider can slide toward or away from the geometric throat in each cavity;

[0006] The upper vertical slider and the lower vertical slider form a group, and the left horizontal slider and the right horizontal slider form a group. The two groups of sliders can slide toward the geometric throat at the same time to change the throat area; each group of sliders can slide toward the geometric throat independently to achieve vector control of the engine.

[0007] Furthermore, connecting holes are provided on two opposite sides of each cavity near the bottom. The connecting hole on one side is connected to the pipeline of the air supply device for introducing gas into the cavity, and the connecting hole on the other side is connected to the exhaust pipeline for discharging the gas in the cavity. The gas flows in the cavity so that the gas pressure in the cavity is equal to the pressure in the combustion chamber, thereby closing the gap between the cavity shell and the slider.

[0008] Furthermore, a connecting rod mechanism, a second sliding block and a first sliding block are arranged at the bottom of each concave cavity; the second sliding block and the first sliding block are both arranged on the shell at the bottom of the concave cavity and can slide along the shell;

[0009] The connecting rod mechanism comprises a long connecting rod and a short connecting rod, and both ends of the long connecting rod are respectively connected to the sliding block and the second sliding block, and are hingedly connected to the second sliding block;

[0010] The two ends of the short connecting rod are respectively connected to the middle part of the long connecting rod and the first sliding block, and are hingedly connected to the first sliding block;

[0011] When the second sliding block slides from the side to the middle, the long connecting rod is pushed to move, which is used to push each slider to slide toward the geometric throat; when the second sliding block slides from the middle to the side, the long connecting rod is pulled to move, which is used to pull each slider to slide away from the geometric throat.

[0012] Furthermore, each second sliding block is connected to an actuating cylinder arranged outside each concave cavity; the actuating cylinder is used to push or pull the second sliding block to slide.

[0013] Furthermore, the upper vertical slider, the lower vertical slider, the left horizontal slider and the right horizontal slider are all composed of an integrally connected rectangular section and an oblique section, and the end of the oblique section is located on the geometric throat side and is vertically arranged; the size of each rectangular section is consistent with the size of the cavity.

[0014] Furthermore, flexible graphite seals are provided between the cavity and each slider and on two opposite sides of the small size of the cuboid to achieve sealing between the cavity housing and each slider.

[0015] Further, the length of the short connecting rod is half the length of the long connecting rod.

[0016] The beneficial effects of the present invention are: 1. By driving four sliders to adjust the area of ​​the combustion chamber of the axisymmetric RBCC engine, efficient operation of different engines under different incoming flow conditions can be achieved; or only one or two sliders can be adjusted to achieve thrust vector control. 2. By using a high-pressure gas cylinder to inject high-pressure gas into the concave cavities of the four sliders, the pressure reducer and the solenoid valve are controlled by the control system to control the concave cavity pressure, so as to match the concave cavity pressure with the combustion chamber pressure, thereby achieving the purpose of air sealing. 3. The slider in the horizontal direction remains stationary, and the two sliders in the vertical direction slide in coordination, so as to achieve the pitch vector control of the aircraft; the two sliders in the vertical direction remain stationary, and the two sliders in the horizontal direction slide in coordination, so as to achieve the yaw control of the aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the configuration diagram of variable geometry throat;

[0018] Figure 2 It is a schematic diagram of the connecting rod mechanism in the cavity;

[0019] Figure 3 Schematic diagram of adjusting throat area for variable geometry throat;

[0020] Figure 4 Schematic diagram of throat adjustment when variable geometry throat performs pitch vector control;

[0021] Among them: 1. Concave cavity gas supply cylinder; 2. Automatic gas pressure reducing valve; 3. Actuator; 4. Concave cavity; 5. Gas cylinder gas supply pipeline; 6. Concave cavity pressure sensor; 7. Upper vertical slider; 8. Combustion chamber shell; 9. Left horizontal slider; 10. Solenoid valve; 11. Lower vertical slider; 12. Combustion chamber pressure sensor; 13. Right horizontal slider; 14. Flexible graphite seal; 16. Exhaust pipeline; 17. Second sliding block; 18. First sliding block; 19. Connecting rod mechanism. DETAILED DESCRIPTION

[0022] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] The present invention provides an adjustable geometric throat with vector regulation for an axisymmetric rocket ramjet combination engine, such as Figure 1 As shown, it includes an axisymmetric combined engine combustion chamber casing 8, and four through holes are arranged circumferentially at intervals outside the geometric throat section of the combustion chamber casing 8, the geometric throat is located at the rear of the combustion chamber, and the four through holes are located at the upper, lower, left and right sides of the geometric throat casing; each through hole is covered with an outwardly protruding casing, and a rectangular concave cavity 4 connected to the geometric throat is formed in the casing.

[0024] A slider is provided in each cavity 4, which are an upper vertical slider 7, a lower vertical slider 11, a left horizontal slider 9 and a right horizontal slider 13; the front end of each slider extends into the geometric throat, and each slider can slide toward or away from the geometric throat in each cavity 4.

[0025] The upper vertical slider 7 and the lower vertical slider 11 form a group, and the left horizontal slider 9 and the right horizontal slider 13 form a group. The two groups of sliders can slide toward the geometric throat at the same time to change the throat area; each group of sliders can slide toward the geometric throat independently to achieve vector control of the engine.

[0026] When the engine thrust vector needs to be adjusted, the sliders need to be adjusted differently. Take the pitch direction vector adjustment as an example: the upper vertical slider 7, the left horizontal slider 9 and the right horizontal slider 13 remain stationary, and the lower vertical slider 11 moves upward. At this time, due to the uneven cross-sectional changes in the flow channel and the existence of the lower vertical slider, the airflow deflects toward the upper part of the flow channel after passing through the geometric throat, generating an upward thrust vector, which can control the aircraft to produce a pitch angle, such as Figure 4 shown.

[0027] If the upper vertical slider 7 and the lower vertical slider 11 remain stationary, one of the left horizontal slider 9 or the right horizontal slider 13 remains stationary, and the other slides, an uneven cross-section change occurs in the flow channel, and yaw control is performed.

[0028] The upper vertical slider 7, the lower vertical slider 11, the left horizontal slider 9 and the right horizontal slider 13 are all composed of an integrally connected rectangular section and a split section, and the split section end is located on the geometric throat side, arranged in a split shape, and arranged vertically, ensuring that it is in the geometric throat; the size of each rectangular section is consistent with the size of the concave cavity 4. The length of the entire slider is 45cm, and the length of the split section is 13.5cm, which is also the initial split section position.

[0029] Connecting holes are provided on two opposite sides near the bottom of each cavity 4. The connecting holes on one side are connected to the pipeline of the gas supply device for introducing gas into the cavity 4, and the connecting holes on the other side are connected to the exhaust pipeline 16 for exhausting the gas in the cavity 4. The gas flows in the cavity 4 to make the gas pressure in the cavity 4 equal to the pressure in the combustion chamber, so as to close the gap between the cavity 4 shell and the slider. The gas supply device uses a gas cylinder 1, and is connected to the gas inlet hole of the cavity 4 through the gas cylinder gas supply pipeline 5. A cavity pressure sensor 6 is provided on the cavity 4 shell. A combustion chamber pressure sensor 12 is installed on the combustion chamber shell 8.

[0030] like Figure 2 As shown, a connecting rod mechanism 19, a second sliding block 17 and a first sliding block 18 are provided at the bottom of each cavity 4; the second sliding block 17 and the first sliding block 18 are both provided at the bottom shell of the cavity 4 and can slide along the shell;

[0031] The connecting rod mechanism 19 includes a long connecting rod and a short connecting rod, and both ends of the long connecting rod are respectively connected to the slider and the second sliding block 17, and are hingedly connected to the second sliding block 17;

[0032] The two ends of the short connecting rod are respectively connected to the middle part of the long connecting rod and the first sliding block 18, and are hingedly connected to the first sliding block 18; the length of the short connecting rod is half of the length of the long connecting rod.

[0033] When the second sliding block 17 slides from the side to the middle, it pushes the long connecting rod to move, which is used to push each slider to slide toward the geometric throat; when the second sliding block 17 slides from the middle to the side, it pulls the long connecting rod to move, which is used to pull each slider to slide away from the geometric throat.

[0034] Each second sliding block 17 is connected to an actuator 3 disposed outside each cavity 4; the actuator 3 is used to push or pull the second sliding block 17 to slide. The actuator 3 is an existing device, and there are many types to choose from. For example, the actuator 3 of the following structure can be used, including an outer cylinder, a piston rod is coaxially disposed in the outer cylinder, and the second sliding block 17 is pushed or pulled by hydraulic control.

[0035] Flexible graphite seals 14 are provided between the cavity 4 and each slider and on two opposite sides of the small size of the cuboid to achieve sealing between the cavity 4 housing and each slider.

[0036] At low incoming flow Mach numbers, the combustion chamber has a smaller demand for the geometric throat area, and at this time the upper vertical slider 7, the lower vertical slider 11, the left horizontal slider 9 and the right horizontal slider 13 are all located at the starting positions.

[0037] The second sliding block 17 is located close to the side of the cavity 4, and the first sliding block 18 is fixed to the bottom of the cavity 4. In order to achieve the effect of air sealing and prevent the gas from leaking from the gap between each slider and the cavity 4, it is necessary to seal the gap between the slider and the cavity 4. In the present invention, air sealing is adopted. According to the pressure feedback of the gas outlet pressure sensor of the combustion chamber and the gas supply device, the switch of the automatic gas pressure reducer and the solenoid valve is adjusted through the control system, and then the gas supply pressure of the gas supply device is adjusted to keep the gas supply pressure the same as the chamber pressure of the combustion chamber to achieve the effect of gas sealing. At the same time, according to the feedback of the pressure sensor of the venting pipeline on the side of the cavity 4, the feedback pressure is transmitted to the controller to control the switch of the exhaust pipeline solenoid valve and the automatic gas pressure reducer. The controller automatically matches and adjusts the pressure of the cavity 4 and the combustion chamber to achieve the effect of gas sealing.

[0038] When the incoming flow Mach number increases, the combustion chamber needs a smaller geometric throat area for efficient combustion. At this time, the four sliders are synchronously and evenly pushed toward the center of the flow channel by the actuator 3. The actuator adopts a hydraulic actuator to push the second sliding block 17, and the connecting rod mechanism 19 moves together with the first sliding block 18. During the movement of the second sliding block 17 toward the first sliding block 18, the long connecting rod of the connecting rod mechanism 19 pushes each slider to slide toward the center of the flow channel in the geometric throat, and the geometric throat area of ​​the combustion chamber is reduced. Figure 3 According to the pressure feedback from the combustion chamber and the gas cylinder gas supply outlet pressure sensor to the controller, the control system controls the switch of the solenoid valve and the automatic gas pressure reducing valve to keep the pressure of the cavity 4 the same as that of the combustion chamber.

[0039] Table 1 gives the pressure data for achieving airtightness:

[0040] Table 1 Pressure matching for achieving air seal at different incoming flow Mach numbers

[0041] Combustion chamber pressure\MPa Concave cavity pressure\Mpa 3Ma 0.118 0.118 4Ma 0.21 0.21 5Ma 0.33 0.33

[0042] In Table 1, the combustion chamber pressure data of Ma3, Ma4, and Ma5 are obtained from the ramjet simulation results. The calculated model is drawn by UG, and the mesh is drawn by FluentMeshing. Finally, Fluent simulation is used to calculate the combustion chamber performance. The calculation requires that the combustion chamber can work normally under the action of the geometric throat and the intake duct and isolation section can work normally. The combustion chamber pressure parameter data is obtained, so that the pressure value required by the cavity can be obtained, so that the gas supply pressure of the gas cylinder can be controlled. According to the gas sealing principle, the slider and the cavity are sealed to prevent combustion chamber gas leakage.

Claims

1. An adjustable geometric throat with vector control for an axisymmetric rocket ramjet engine, characterized in that: It comprises an axisymmetric combined engine combustion chamber casing (8), wherein four through holes are arranged circumferentially and spaced apart from each other on the outer side of the geometric throat section of the combustion chamber casing (8), and the four through holes are located at the upper, lower, left and right sides of the geometric throat casing; each through hole is covered with a casing protruding outward, and a rectangular parallelepiped concave cavity (4) connected to the geometric throat is formed in the casing; A slider is arranged in each of the concave cavities (4), namely an upper vertical slider (7), a lower vertical slider (11), a left horizontal slider (9) and a right horizontal slider (13); the front end of each slider extends into the geometric throat, and each of the sliders can slide towards or away from the geometric throat in each concave cavity (4); The upper vertical slider (7) and the lower vertical slider (11) form a group, and the left horizontal slider (9) and the right horizontal slider (13) form a group. The two groups of sliders can slide toward the geometric throat at the same time to change and adjust the throat area; each group of sliders can slide toward the geometric throat independently to achieve vector control of the engine.

2. The adjustable geometric throat with vector control for an axisymmetric rocket ramjet combination engine according to claim 1, characterized in that: Connecting holes are provided on two opposite sides near the bottom of each cavity (4). The connecting hole on one side is connected to a pipeline of a gas supply device for introducing gas into the cavity (4), and the connecting hole on the other side is connected to an exhaust pipeline for exhausting gas in the cavity (4). The gas flows in the cavity (4) so ​​that the gas pressure in the cavity (4) is equal to the pressure in the combustion chamber, thereby closing the gap between the cavity (4) shell and the slider.

3. The adjustable geometric throat with vector control for an axisymmetric rocket ramjet combination engine as claimed in claim 2, characterized in that: A connecting rod mechanism (19), a second sliding block (17) and a first sliding block (18) are arranged at the bottom of each of the concave cavities (4); the second sliding block (17) and the first sliding block (18) are both arranged on the bottom shell of the concave cavity (4) and can slide along the shell; The connecting rod mechanism (19) comprises a long connecting rod and a short connecting rod, and the two ends of the long connecting rod are respectively connected to the slider and the second sliding block (17), and are hingedly connected to the second sliding block (17); The two ends of the short connecting rod are respectively connected to the middle part of the long connecting rod and the first sliding block (18), and are hingedly connected to the first sliding block (18); When the second sliding block (17) slides from the side to the middle, the long connecting rod is pushed to move, so as to push each slider to slide toward the geometric throat; when the second sliding block (17) slides from the middle to the side, the long connecting rod is pulled to move, so as to pull each slider to slide away from the geometric throat.

4. The adjustable geometric throat with vector control for an axisymmetric rocket ramjet combination engine as claimed in claim 3, characterized in that: Each of the second sliding blocks (17) is connected to an actuating cylinder (3) arranged outside each cavity (4); the actuating cylinder (3) is used to push or pull the second sliding block (17) to slide.

5. The adjustable geometric throat with vector control for an axisymmetric rocket ramjet combination engine as claimed in claim 4, characterized in that: The upper vertical slider (7), the lower vertical slider (11), the left horizontal slider (9) and the right horizontal slider (13) are all composed of a rectangular section and an oblique section connected in one piece, and the end of the oblique section is located on the geometric throat side and is vertically arranged; the size of each of the rectangular sections is consistent with the size of the concave cavity (4).

6. The adjustable geometric throat with vector control for an axisymmetric rocket ramjet combination engine as claimed in claim 5, characterized in that: Flexible graphite seals (14) are provided between the concave cavity (4) and each slider and on two opposite sides of the small size of the cuboid, for achieving sealing between the concave cavity (4) housing and each slider.

7. The adjustable geometric throat with vector control for an axisymmetric rocket ramjet combination engine as claimed in claim 6, characterized in that: The length of the short connecting rod is half the length of the long connecting rod.

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