A variable geometry throat for a semi-axisymmetric rocket-based combined engine

Abstract

The present invention discloses a variable geometry throat for a semi-axisymmetric rocket-based combined engine, comprising: an axially connected intake duct and a combustion chamber, wherein both the intake duct and the combustion chamber are cavity structures surrounded by a shell; the intake duct's shell is composed of a first bottom plate and a first top plate, wherein the first bottom plate is horizontal; the first top plate is an upwardly arched semi-trumpet-shaped; the combustion chamber is composed of a straight section and a curved section with the same inner diameter and connected front and back; the shell is composed of a second bottom plate and a second top plate, wherein the second bottom plate is composed of a horizontal section connected front and back and a downwardly curved section, the front end of the horizontal section being integrally connected to the first bottom plate; the second top plate is composed of two semi-cylindrical shells connected front and back. The variable geometry throat improves thrust and specific impulse performance over a wide operating range, while achieving efficient combustion in the RBCC engine's combustion chamber under different modes and meeting air flow matching requirements under different incoming flow conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of flow passages of rocket-based combined cycle engines, and in particular relates to a variable geometry throat for a semi-axisymmetric rocket-based combined cycle engine. Background Art

[0002] The Rocket-Based Combined Cycle (RBCC) engine is a combined propulsion system that organically integrates a high thrust-to-weight ratio, low specific impulse rocket engine with a low thrust-to-weight ratio, high specific impulse ramjet engine. RBCC engines integrate ejection, subsonic, scramjet, and pure rocket modes. This enables self-starting, a wide flight envelope, and strong mission adaptability, making them one of the most promising new propulsion systems for the future. Given that multiple modes share a single flow path, variable engine structure technology is one of the most effective ways to ensure optimal performance throughout the entire engine lifecycle.

[0003] Domestic researchers have proposed variable-structure rocket-based combined power cycle engines and variable-structure combustion chambers of rocket-based combined power cycle engines (RBCCs). In the former, the adjustable top plate of the combustion chamber slides back and forth along the direction of the fixed top plate of the combustion chamber to change the combustion chamber area, while the latter uses the variable surface segment of the upper wall of the combustion chamber to change the combustion chamber area ratio. However, there are few studies on the variable-structure combustion chamber scheme of the axisymmetric RBCC engine. In addition, in terms of integration into the airframe, semi-axisymmetric engines are easier to integrate into the airframe than binary engines. Therefore, studying the variable-structure scheme of the axisymmetric RBCC is extremely important for improving its engine performance. Summary of the Invention

[0004] The purpose of the present invention is to provide a variable throat for a semi-axisymmetric rocket-based combination engine, so as to improve its thrust and specific impulse performance when working in a wide range, and at the same time realize efficient combustion in the RBCC engine combustion chamber under different modes, so as to meet the matching of air flow under different incoming flow conditions.

[0005] The present invention adopts the following technical solution: a variable geometry throat for a semi-axisymmetric rocket-based combined engine, comprising: an air intake duct and a combustion chamber connected in the axial direction, and an air intake duct outer cover, wherein: the air intake duct and the combustion chamber are both cavity structures surrounded by a shell;

[0006] The air inlet duct has a housing composed of a first bottom plate and a first top plate, wherein the first bottom plate is horizontal; the first top plate is an upwardly arched semi-trumpet shape, with the outward-expanding trumpet mouth located at the front end; the first top plate and the first bottom plate are slidably connected;

[0007] The combustion chamber is composed of a straight segment and a curved segment with the same inner diameter and connected front to back. Its shell is composed of a second bottom plate and a second top plate. Corresponding to the straight segment and the curved segment, the second bottom plate is composed of a horizontal segment connected front to back and a curved segment that bends downward. The front end of the horizontal segment is integrally connected to the first bottom plate. The second top plate is composed of two semi-cylindrical shells connected front to back, with the straight edges of each semi-cylindrical shell parallel to the corresponding horizontal segment and curved segment.

[0008] The rear end of the bending section is connected to a horizontal nozzle;

[0009] The air inlet cover is semi-cylindrical and is mounted on the outside of the arched side of the air inlet. Its bottom is slidably connected to the bottom plate and can move forward and backward along the bottom plate.

[0010] The air inlet cover and the air inlet shell move forward or backward at the same time. When they move forward, the area of ​​the air inlet throat is reduced; when they move backward, the area of ​​the air inlet throat is increased.

[0011] Furthermore, it also includes a combustion chamber geometric throat adjustment block, which is arranged on the base plate inside the nozzle. It is a double semi-cone connected in the axial direction and with the tip facing the front and rear ends. Its flat side is attached to the wall of the base plate and can be moved forward and upward into the nozzle or moved backward and downward to be reset. When moving forward and upward, the area of ​​the geometric throat is reduced, and when moving backward and downward, the area of ​​the geometric throat is increased.

[0012] Furthermore, the nozzle is surrounded by a bottom plate and a top plate. The bottom plate is aligned with the plate at the bottom of the bent section. The top plate is an upwardly arched shape that expands smoothly from front to back.

[0013] Furthermore, at least two air inlet actuators are provided on the outer wall of the top plate of the straight section and near the end of the air inlet, and the two air inlet actuators are arranged around the top plate at intervals;

[0014] A plurality of first actuating blocks are provided at the rear end of the first top plate of the air inlet duct. The number of the first actuating blocks is the same as the number of the air inlet duct actuating cylinders, and the positions of the first actuating blocks are consistent. One first actuating block is connected to one air inlet duct actuating cylinder. Each first actuating block is a block-shaped body.

[0015] Each air inlet duct actuator is used to push the first top plate to move forward and backward along the first bottom plate.

[0016] Furthermore, an air intake throat regulating block actuator is provided at the rear end of the air intake outer cover, and the air intake throat regulating block actuator is used to push the air intake outer cover to move forward and backward.

[0017] Furthermore, the length of the front end semi-cone of the combustion chamber geometric throat adjustment block is equal to the length of the bending section.

[0018] Furthermore, the front end of the air inlet cover passes over the front end edge of the air inlet, and the rear end is located at the contraction section in the air inlet.

[0019] Furthermore, in the air inlet duct, the coaxial sleeve is provided with an air inlet duct center body, which is a semi-cone with a pointed front end, and its flat side is attached to the bottom plate side, forming a semi-annular channel between it and the first top plate.

[0020] The beneficial effects of the present invention are as follows: 1. The intake duct actuator pushes the first top plate forward and backward to change the intake duct contraction ratio. When the first top plate moves forward, the intake duct contraction ratio decreases, meeting the high Mach intake duct requirements; when the first top plate moves backward, the intake duct contraction ratio increases, meeting the low Mach intake duct requirements. The intake duct throat adjustment block actuator pushes the intake duct outer cover forward and backward to adjust the intake duct external contraction ratio. When the intake duct outer cover moves forward, the external contraction ratio increases, meeting the high Mach intake duct requirements; when the intake duct outer cover moves backward, the external contraction ratio decreases, meeting the low Mach intake duct requirements. By adjusting the intake duct contraction ratio, the matching of the intake and exhaust systems is met. 2. At low Mach, the combustion chamber geometric throat adjustment block moves backward to increase the combustion chamber geometric throat area. At high Mach, the combustion chamber geometric throat adjustment block moves forward to reduce the combustion chamber geometric throat area, thereby improving the engine's choking capacity and generating a large force. To achieve different inflow and fuel matching in the combustion chamber, and achieve stable and efficient combustion performance. 3. The intake duct geometry throat and the combustion chamber geometry throat have only one degree of freedom, and the adjustment method is simple and easy to achieve geometry. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The figure is a schematic diagram of the structure of a variable geometry throat for a semi-axisymmetric rocket-based combined engine;

[0022] Figure 2 This is a diagram showing the connection between the intake manifold actuator, the intake manifold, and the combustion chamber;

[0023] Figure 3 This is a diagram of the actuator for the contraction section in the intake duct;

[0024] Figure 4 This is a schematic diagram of the structure of the combustion chamber geometric throat adjustment block;

[0025] Among them: 1. Inlet center body; 2. Inlet; 3. Inlet outer cover; 4. Inlet throat adjustment block actuator; 5. Support plate rocket; 6. Fuel injection support plate; 7. Combustion chamber geometry throat adjustment block actuator; 8. Combustion chamber geometry throat adjustment block; 9. Inlet actuator; 10. First actuator block; 11. Second actuator block; 12. Combustion chamber; 12-1. Straight section; 12-2. Bend section; 13. Nozzle. DETAILED DESCRIPTION

[0026] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] The present invention provides a variable geometry throat for a semi-axisymmetric rocket-based combined engine, such as Figure 1 As shown, the air intake duct 2 and the combustion chamber 12 are connected in the axial direction, and further include an air intake duct outer cover 3, wherein: the air intake duct 2 and the combustion chamber 12 are both cavity structures surrounded by a shell;

[0028] The air inlet 2, whose shell consists of a first bottom plate and a first top plate, wherein the first bottom plate is horizontal; the first top plate is an upwardly arched semi-trumpet shape, and the outward-expanding trumpet mouth is located at the front end; the first top plate and the first bottom plate are slidingly connected; inside the air inlet 2, an air inlet center body 1 is coaxially sleeved, which is a semi-conical shape with a pointed front end, and its flat side is attached to the bottom plate side, forming a semi-annular channel between it and the first top plate.

[0029] Combustion chamber 12 is composed of a straight section 12-1 and a curved section 12-2, both of the same inner diameter and connected front to back. Its housing consists of a second bottom plate and a second top plate. Corresponding to straight section 12-1 and curved section 12-2, the second bottom plate comprises a horizontal section connected front to back and a downwardly curved section. The front end of the horizontal section is integrally connected to the first bottom plate. The second top plate comprises two semi-cylindrical shells connected front to back, with the straight edges of each semi-cylindrical shell parallel to the corresponding horizontal and curved sections.

[0030] The rear end of the bending section 12-2 is connected to a horizontal nozzle 13;

[0031] The air inlet cover 3 is semi-cylindrical and is mounted on the outer side of the arch of the air inlet 2. Its bottom is slidably connected to the bottom plate and can move forward and backward along the bottom plate.

[0032] The air inlet cover 3 and the outer shell of the air inlet 2 move forward or backward at the same time. When they move forward, the area of ​​the throat of the air inlet 2 is reduced; when they move backward, the area of ​​the throat of the air inlet 2 is increased.

[0033] like Figure 2 、 3 As shown in Figure 4, it also includes a combustion chamber geometric throat adjustment block 8. The combustion chamber geometric throat adjustment block 8 is arranged on the bottom plate inside the nozzle 13. It is a double semi-cone connected in the axial direction and with the tip facing the front and rear ends. Its flat side is attached to the wall of the bottom plate and can be moved forward and upward into the nozzle or moved backward and downward to be reset. When moving forward and upward, the area of ​​the geometric throat is reduced, and when moving backward and downward, the area of ​​the geometric throat is increased.

[0034] An intake throat adjustment block actuator 4 is installed at the rear end of the intake cover 3. This actuator 4 is used to propel the intake cover 3 forward and backward. The front end of the actuator 4 is connected to the inner constriction of the intake duct 2 via a second actuator block 11. This second actuator block 11 is a cone that conforms to the curvature of the inner constriction's outer wall. Alternatively, it can be a curved block, designed to conform to the outer wall of the inner constriction.

[0035] The nozzle 13 is surrounded by a bottom plate and a top plate. The bottom plate is aligned with the bottom plate of the bending section 12-2. The top plate is an upwardly arched arch that expands smoothly from front to back.

[0036] At least two air inlet duct actuators 9 are provided on the outer wall of the top plate of the straight section 12 - 1 and near the end of the air inlet duct 2 . The two air inlet duct actuators 9 are arranged at intervals around the top plate.

[0037] A plurality of actuating blocks 10 are provided at the rear end of the top plate of the air inlet duct 2. The number of actuating blocks 10 is the same as the number of the air inlet duct actuating cylinders 9, and the positions are consistent. One actuating block 10 is connected to one air inlet duct actuating cylinder 9. Each actuating block 10 is a block-shaped body, such as a cube, which serves as a connection.

[0038] Each air inlet duct actuator 9 is used to push the first top plate to move forward and backward along the first bottom plate.

[0039] The length of the front half cone of the combustion chamber geometric throat adjustment block 8 is equal to the length of the bending section 12-2.

[0040] The air inlet 2, the air inlet cover 3 and the combustion chamber geometric throat adjustment block 8 are all slidably connected to the base plate, such as by using a slideway opened on the base plate, and adopting a dynamic seal.

[0041] The actuator cylinder in this embodiment is an existing device, and there are many types to choose from. For example, an actuator cylinder with the following structure can be used, including an outer cylinder with a piston rod coaxially arranged inside the outer cylinder, which can achieve pushing or pulling through hydraulic control.

[0042] In order to verify the variable geometry throat of the semi-axisymmetric rocket-based combined engine of the present invention, a simulation experiment was conducted as follows:

[0043] When the engine is operating at Ma2, the intake shroud 3 and the combustion chamber geometric throat adjustment block 8 are in their initial positions. Specifically, the intake shroud 3 and the combustion chamber geometric throat adjustment block 8 are completely within the nozzle 13. The intake duct capture area is 1, the intake duct throat area is 0.2855, the maximum combustion chamber cross-sectional area is 0.67, and the combustion chamber geometric throat area is 0.0625. To ensure normal operation of the intake duct, the intake duct overflow flow rate is large at this time, and its throat area is also large.

[0044] When the engine is working at Ma3, the intake duct outer cover 3 moves forward 95mm, and the combustion chamber geometric throat adjustment block 8 moves forward 20mm. At this time, the intake duct throat area becomes 0.2665, and the combustion chamber geometric throat area and the maximum cross-sectional area of ​​the combustion chamber 12 remain unchanged, ensuring that the intake duct captures the flow rate. At this time, the intake duct start-up requirements can be met, and the combustion chamber throat adjustment maintains the working state when the Ma3 flow comes.

[0045] During the Ma3 to Ma6 transition, to adapt to the dramatic changes in incoming airflow and ensure the engine does not stall, specifically to maintain the inlet's startup performance, the inlet's inner constriction section is moved forward 42.5mm to reduce the throat area, and the inlet cover 3 is moved forward 65mm to ensure the inlet's startup characteristics. The inlet throat area is reduced to 0.1590, while the inlet 2 capture area and the maximum cross-sectional area of ​​the combustion chamber 12 remain unchanged. Simultaneously, the combustion chamber's geometric throat adjustment block 8 is moved forward 310mm along the nozzle to within the bend 12-2. This reduces the geometric throat area, increases engine congestion, and enhances combustion heat release in the combustion chamber 12, thereby increasing the pressure in the combustion chamber 12 and improving the engine's thrust-specific impulse performance. The combustion chamber's geometric throat is then reduced to a size sufficient to meet the fuel combustion requirements, with the geometric throat area reduced to 0.2850. The throat adjustment maintains the operating state of the Ma3 incoming airflow. In the present invention, by adjusting the geometric throat position and the intake duct contraction ratio, it is possible to achieve matching of different incoming flows and injection states of the combustion chamber 12.

[0046] At incoming flow Mach numbers of 2, 3, and 6, the combustion chamber geometric throat adjustment block 8 is located at 0mm, 0mm, and 310mm, respectively. Specifically, when the combustion chamber geometric throat adjustment block 8 is completely within the nozzle 13, the rear end of the combustion chamber geometric throat adjustment block 8 is defined as point 0. As it slides toward the forward bend 12-2, its rear end moves forward from point 0 by a positive distance. As the combustion chamber geometric throat adjustment block 8 moves forward, the geometric throat area decreases and the congestion level of the combustion chamber 12 increases, effectively achieving efficient engine operation under varying incoming flow conditions. The geometric throat adjustment block 8 is actuated solely by the actuator 7, resulting in a simple actuation method.

Claims

1. A variable geometry throat for a semi-axisymmetric rocket-based combined engine, characterized in that: include: An air intake duct (2) and a combustion chamber (12) are connected in the axial direction, and further comprises an air intake duct outer cover (3), wherein: the air intake duct (2) and the combustion chamber (12) are both cavity structures surrounded by a shell; The air inlet (2) has a shell composed of a first bottom plate and a first top plate, wherein the first bottom plate is horizontal; the first top plate is an upwardly arched semi-trumpet shape, with the outward-expanding trumpet mouth located at the front end; the first top plate and the first bottom plate are slidably connected; The combustion chamber (12) is composed of a straight section (12-1) and a bent section (12-2) having the same inner diameter and connected front to back; its shell is composed of a second bottom plate and a second top plate, corresponding to the straight section (12-1) and the bent section (12-2), the second bottom plate is composed of a horizontal section connected front to back and a bent section bent downward, the front end of the horizontal section is connected to the first bottom plate in an integral manner; the second top plate is composed of two semi-cylindrical shells connected front to back, and the straight edge of each semi-cylindrical shell is parallel to the corresponding horizontal section and bent section; The rear end of the bending section (12-2) is connected to a horizontal nozzle (13); The air inlet duct outer cover (3) is semi-cylindrical and is sleeved on the outside of the arched side of the air inlet duct (2). Its bottom is slidably connected to the bottom plate and can move forward and backward along the bottom plate. The air inlet duct outer cover (3) and the air inlet duct (2) shell move forward or backward at the same time. When moving forward, the area of ​​the throat of the air inlet duct (2) is reduced; when moving backward, the area of ​​the throat of the air inlet duct (2) is increased.

2. A variable geometry throat for a semi-axisymmetric rocket-based combined engine according to claim 1, characterized in that: The combustion chamber geometric throat regulating block (8) is also included. The combustion chamber geometric throat regulating block (8) is arranged on the bottom plate in the nozzle (13). The block is a double semi-cone connected in the axial direction and with its tip facing the front and rear ends. The flat side of the block is attached to the wall of the bottom plate and can move forward and upward in the nozzle or move backward and downward to reset. When moving forward and upward, the area of ​​the geometric throat is reduced, and when moving backward and downward, the area of ​​the geometric throat is increased.

3. A variable geometry throat for a semi-axisymmetric rocket-based combined engine according to claim 2, characterized in that: The nozzle (13) is surrounded by a bottom plate and a top plate. The bottom plate is aligned with the plate at the bottom of the bending section (12-2). The top plate is in an upwardly arched shape and expands smoothly from front to back.

4. A variable geometry throat for a semi-axisymmetric rocket-based combined engine as claimed in claim 3, characterized in that: At least two air inlet duct actuators (9) are provided on the outer wall of the top plate of the straight section (12-1) and located near the end of the air inlet duct (2), and the two air inlet duct actuators (9) are arranged at intervals around the top plate; A plurality of first actuating blocks (10) are provided at the rear end of the first top plate of the air inlet duct (2). The number of the first actuating blocks (10) is the same as the number of the air inlet duct actuating cylinders (9), and the positions of the first actuating blocks (10) are consistent. One first actuating block (10) is connected to one air inlet duct actuating cylinder (9); each first actuating block (10) is a block-shaped body. Each of the air inlet duct actuators (9) is used to push the first top plate to move forward and backward along the first bottom plate.

5. The variable geometry throat for a semi-axisymmetric rocket-based combined engine according to claim 4, characterized in that: An air intake throat regulating block actuator (4) is provided at the rear end of the air intake outer cover (3), and the air intake throat regulating block actuator (4) is used to push the air intake outer cover (3) to move forward and backward.

6. A variable geometry throat for a semi-axisymmetric rocket-based combined engine according to claim 5, characterized in that: The combustion chamber geometric throat adjustment block (8) has a front end semi-cone having a length equal to that of the bending section (12-2).

7. A variable geometry throat for a semi-axisymmetric rocket-based combined engine according to claim 6, characterized in that: The front end of the air inlet duct outer cover (3) passes over the front end edge of the air inlet duct (2), and the rear end is located at the contraction section in the air inlet duct.

8. The variable geometry throat for a semi-axisymmetric rocket-based combined engine according to claim 7, characterized in that: In the air inlet (2), a coaxial sleeve is provided with an air inlet center body (1), which is a semi-conical body with a pointed front end, and its flat side is attached to the bottom plate side, forming a semi-annular channel between it and the first top plate.

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