Solid-liquid rocket engine with star-shaped double-layer charging function

Abstract

The invention relates to a star-shaped double-layer charging solid-liquid rocket engine, and belongs to the technical field of rocket engines, the star-shaped double-layer charging solid-liquid rocket engine comprises a first combustion cylinder, a second combustion cylinder, a third combustion cylinder, a catalytic bed and an end socket, and a first star-shaped fuel layer, a second star-shaped fuel layer and a first annular heat insulation layer are poured in the first combustion cylinder in a wall-attached mode; the second combustion cylinder and the third combustion cylinder are connected to the two open ends of the first combustion cylinder through flange plates correspondingly. The catalytic bed is fixed at one opening end of the second combustion cylinder through a flange plate; the sealing head is fixed to one opening end of the third combustion cylinder through a flange plate. The first star-shaped fuel layer and the second star-shaped fuel layer are sequentially poured on the inner cylinder wall of the first combustion cylinder from inside to outside in a wall-attached mode, the first star-shaped fuel layer uses high-energy fuel to generate large thrust in the initial working stage, and the second star-shaped fuel layer uses common fuel to work for a long time with small thrust. The two-layer charge combustion works under the optimal oxygen-fuel ratio, and the comprehensiveness of the solid-liquid rocket engine can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of rocket engines, in particular to a star-shaped double-layered solid-liquid rocket engine. Background Art

[0002] The propellant of a typical solid-liquid rocket engine is composed of solid fuel and liquid oxidizer. Compared with traditional solid rocket engines, it has some obvious advantages, such as multiple launches on demand, higher specific impulse performance, wide range of thrust adjustment, long operation time and better safety. Compared with liquid rocket engines, solid-liquid rocket engines have a simple structure and a higher density specific impulse.

[0003] In actual engineering model applications, solid-liquid rocket engines are limited by the lower burning rate caused by non-premixed diffusion combustion. In order to pursue the performance requirements of high thrust and high specific impulse, high-performance fuels are often used. These fuels contain high-energy additives such as octogenol (HMX), RDX and aluminum hydride (Al H3).

[0004] However, the presence of high-energy additives is not conducive to taking advantage of the deep variable thrust and multiple starts and stops of solid-liquid rocket engines. Specifically, high-energy components will continue to undergo physical or chemical reactions after the engine is shut down. For example, HMX and RDX will continue to burn and cannot self-extinguish after the engine is shut down, and Al H3 will decompose into aluminum (Al) and hydrogen (H2) under high temperature conditions; this will cause changes in the surface composition of the solid propellant, which is not conducive to the next start and control, and makes the solid-liquid rocket engines lose the advantage of repeated starts and stops.

[0005] In order to solve the above technical problems, a double-layer solid-liquid rocket engine was developed. There is no very specific content in the current public information, but the solid fuel charge structure in the solid-liquid rocket engine is similar to that of the solid rocket engine. The former often uses the latter's charge shape in actual use, such as tube-shaped charge, star-shaped charge and wheel-shaped charge, which has a certain reference when designing solid-liquid rocket engines. For solid rocket engines, the technology of using one combustion chamber to generate two-stage thrust is called single-chamber dual-thrust technology. There are generally two technical solutions:

[0006] Scheme 1: Single chamber dual thrust scheme by changing the combustion surface; variable cross-section charge is a common method to change the combustion area, such as Figure 1 Different grain arrangement schemes are adopted along the central axis of the engine. However, the different thickness of the front and rear propellants will cause the rear propellant to burn out first, which is a severe test for the thermal protection of the combustion chamber shell. In addition, the rear grain filling coefficient is small, which may cause a reduction in the total impulse of the engine.

[0007] Option 2: Change the combustion surface retreat speed to obtain dual thrust; this dual thrust form is mainly achieved by using two different types of propellants. Figure 2 As shown, the first stage uses a high burning rate propellant, and the second stage uses a lower burning rate propellant. These two different propellants can be arranged along the engine axis or radially concentrically. Figure 2 (a) The scheme is not suitable for double-layer solid-liquid rocket engines because it has no grain column channel and is difficult to inject oxidizer; Figure 2 (b) The solution also has the problem of partial propellant burning out first and thermal protection of the combustion chamber, and is not suitable for double-layer solid-liquid rocket engines; Figure 2 (c) The partial radial double-layer charge scheme is adopted, but there is a problem of difficulty in pouring special-shaped grain columns, and it is not suitable for double-layer charge solid-liquid rocket engines; Figure 2 (d) An integral radial charge scheme is adopted, and the geometric form of this structure can basically serve as a reference for the double-layer charge of the solid-liquid rocket engine of this patent.

[0008] The present invention aims to provide a solution to solve the above-mentioned problem, namely, applying a double-layer charge scheme to a solid-liquid rocket engine, so that the first layer of high-energy fuel is used in a high-thrust boosting period that does not require repeated starts and stops, and the second layer of ordinary fuel is used in a low-thrust cruise stage, so that the solid-liquid rocket engine has both high thrust and high specific impulse performance and multiple start-stop capabilities. Summary of the invention

[0009] The invention provides a star-shaped double-layer solid-liquid rocket engine, which solves the technical problems of low total impulse, small thrust and difficulty in repeated starting and stopping of existing dual-thrust solid-liquid rocket engines.

[0010] The technical solution of the present invention to solve the above technical problems is as follows: a star-shaped double-layer solid-liquid rocket engine, comprising: a first combustion tube, a second combustion tube, a third combustion tube, a catalytic bed and a head.

[0011] The interior of the first combustion tube is cast with a first star-shaped fuel layer, a second star-shaped fuel layer and a first annular insulation layer from the inside to the outside, and the interior of the first star-shaped fuel layer has an inner channel of the charge column; the second combustion tube and the third combustion tube are respectively connected to the two open ends of the first combustion tube through flanges; the catalytic bed is fixed to an open end of the second combustion tube away from the first combustion tube through a flange; the head is fixed to an open end of the third combustion tube away from the first combustion tube through a flange.

[0012] The beneficial effects of the present invention are:

[0013] 1. Improve the structure of the traditional solid-liquid rocket engine. The first star-shaped fuel layer and the second star-shaped fuel layer are cast on the inner wall of the first combustion tube from the inside to the outside. The first star-shaped fuel layer uses high-energy fuel to generate a large thrust at the beginning of work, and the second star-shaped fuel layer uses ordinary fuel to work for a long time with a small thrust. Since the two layers of charge work at the optimal oxygen-fuel ratio during combustion, the comprehensiveness of the solid-liquid rocket engine is improved; in addition, the first star-shaped fuel layer and the second star-shaped fuel layer have the same shape when they are burned out according to the parallel layer combustion law. In theory, the engine will have two independent working stages, and the combustion of the two layers of fuel will not affect each other, which simplifies the difficulty of design and simulation.

[0014] 2. The double-layer charge scheme is applied to solid-liquid rocket engines. The first star-shaped fuel layer uses high-energy fuel to generate greater thrust at the beginning of operation, and the second star-shaped fuel layer uses ordinary fuel to work for a longer time with small thrust, and has repeated start and stop capabilities. The two-layer charge shape and oxidizer flow are designed to make the engine always operate near the optimal oxygen-fuel ratio.

[0015] Based on the above technical solution, the present invention can also be improved as follows.

[0016] Furthermore, the cross-sections of the first star-shaped fuel layer and the second star-shaped fuel layer are both six-star structures.

[0017] The further beneficial effects of adopting the above method are: the star-shaped charge can increase the combustion area of ​​the charge column, enhance the heat transfer between the fuel gas and the wall of the charge column, and increase the burning rate and fuel flow rate.

[0018] Furthermore, the first star-shaped fuel layer uses 40% to 60% of butyl hydroxyl fuel, 30% to 50% of aluminum and 5% to 15% of octogold; the second star-shaped fuel layer uses 65% to 75% of butyl hydroxyl fuel and 25% to 55% of aluminum.

[0019] Furthermore, a second annular heat insulating layer is fixed on the inner wall of the second combustion tube, and a third annular heat insulating layer is fixed on the inner wall of the third combustion tube.

[0020] Furthermore, the catalytic bed includes a catalytic tube, a catalytic body and a catalytic cover plate, an open end of the catalytic tube is connected to an open end of the second combustion tube away from the first combustion tube through a flange; the catalytic body is placed in the catalytic tube; the catalytic cover plate is fixed to the other open end of the catalytic tube away from the second combustion tube.

[0021] The above further beneficial effect is that the catalytic body uses a high concentration of 98% hydrogen peroxide with a flow rate of 200g / s as an oxidant, and the hydrogen peroxide is decomposed into high-temperature oxygen and water vapor after passing through the catalytic bed, so that the solid fuel is pyrolyzed. The combustion chamber of the solid-liquid rocket engine is located in the grain column channel, and the oxidant and the fuel of the solid fuel pyrolysis are burned here, converting chemical energy into heat energy.

[0022] Furthermore, the sealing head also includes an annular sealing head insulation layer, and the annular sealing head insulation layer is penetrated and fixed on the inner cylinder wall of the sealing cylinder.

[0023] Furthermore, an annular sealing head heat insulation layer is fixed on the inner cylinder wall of the sealing cylinder.

[0024] Furthermore, the first annular thermal insulation layer, the second annular thermal insulation layer, the third annular thermal insulation layer and the head thermal insulation layer are all made of high-silicon oxide material.

[0025] A further beneficial effect of adopting the above method is that the high-silicon-oxygen material can be used to isolate heat and extend the service life of the second combustion tube, the third combustion tube and the sealing tube.

[0026] Furthermore, it also includes a nozzle and a pressure plate, wherein the nozzle is inserted into the sealing tube; the pressure plate is fixed to the opening end of the sealing tube away from the third combustion tube and fixed to the nozzle.

[0027] Furthermore, the nozzle is a tungsten-copper-infiltrated Laval nozzle.

[0028] A further beneficial effect of adopting the above is that the function of the Laval nozzle is to convert the thermal energy of the high-temperature combustion gas into kinetic energy through expansion, and to generate thrust by the recoil effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a single-chamber dual-thrust solution for solid rocket engines by changing the combustion surface;

[0030] Figure 2 A single-chamber dual-thrust scheme for solid rocket engines to change the combustion surface recession speed;

[0031] Figure 3 It is a structural schematic diagram of a star-shaped double-layer charge solid-liquid rocket engine of the present invention;

[0032] Figure 4 for Figure 3 Schematic diagram of the cross-section structure at AA;

[0033] Figure 5 for Figure 4 Schematic diagram of the cross-section structure at BB;

[0034] Figure 6A geometric parameter diagram of a second star-shaped fuel layer and a first star-shaped fuel layer in a solid-liquid rocket engine with a star-shaped double-layer charge according to the present invention;

[0035] Figure 7 A thrust diagram for predicting the internal passage of a grain column in a solid-liquid rocket engine with a star-shaped double-layer charge according to the present invention;

[0036] Figure 8 The figure is a diagram of oxygen-fuel ratio distribution in a solid-liquid rocket engine with a star-shaped double-layer charge according to the present invention.

[0037] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0038] 1. First combustion tube, 2. Second combustion tube, 3. Third combustion tube, 4. Catalytic bed, 41. Catalytic tube, 42. Catalytic body, 43. Catalytic cover plate, 5. Head, 51. Sealing tube, 52. Annular head insulation layer, 6. First star-shaped fuel layer, 7. Second star-shaped fuel layer, 8. First annular insulation layer, 9. Second annular insulation layer, 10. Third annular insulation layer, 11. Nozzle, 12. Pressure plate. DETAILED DESCRIPTION

[0039] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0040] like Figure 3 and Figure 4 As shown, a star-shaped double-layer solid-liquid rocket engine comprises: a first combustion tube 1, a second combustion tube 2, a third combustion tube 3, a catalytic bed 4 and a head 5.

[0041] The interior of the first combustion tube 1 is cast with a first star-shaped fuel layer 6, a second star-shaped fuel layer 7 and a first annular insulation layer 8 in sequence from the inside to the outside, and the interior of the first star-shaped fuel layer 6 has an inner channel of the charge column; the second combustion tube 2 and the third combustion tube 3 are respectively connected to the two open ends of the first combustion tube 1 through flanges; the catalytic bed 4 fixes an open end of the second combustion tube 2 away from the first combustion tube 1 through a flange; the head 5 is fixed to an open end of the third combustion tube 3 away from the first combustion tube 1 through a flange.

[0042] like Figure 5 and Figure 6 As shown, in some specific embodiments, the cross-sections of the first star-shaped fuel layer 6 and the second star-shaped fuel layer 7 can both be six-star structures.

[0043] In some specific embodiments, the first star-shaped fuel layer 6 uses 40% to 60% butyl hydroxyl fuel, 30% to 50% aluminum and 5% to 15% octogenol; the second star-shaped fuel layer 7 uses 65% to 75% butyl hydroxyl fuel and 25% to 55% aluminum.

[0044] In order to ensure that the first stage of the engine produces high thrust and high specific impulse, HMX and Al are added to the first layer of hydroxybutane fuel (HTPB); in order to take into account good repeated starting performance, only Al is added to the second layer of fuel HTPB. The specific propellant formula and density are shown in Table 1 below:

[0045] Table 1 Propellant formula

[0046]

[0047] In engineering practice, solid-liquid rocket engines often use a variety of charging methods such as tubular, star-shaped, and wheel-shaped. Tubular charges have a simple structure and are easy to process, but are not suitable for double-layer charge design due to their small initial combustion surface. Star-shaped and wheel-shaped charges can increase the combustion area of ​​the grain, enhance heat transfer between the fuel gas and the wall of the grain, and increase the burning rate and fuel flow rate. However, since the wheel-shaped charge has the disadvantage of poor mechanical properties in the later stage of engine operation, a star-shaped charge is used. In this example, a star-shaped charge with six star corners is used. The specific geometric parameters are as follows:

[0048] Table 2 Geometric parameters of drug shape

[0049]

[0050] In some specific embodiments, a second annular heat insulating layer 9 is fixed on the inner wall of the second combustion tube 2 , and a third annular heat insulating layer 10 is fixed on the inner wall of the third combustion tube 3 .

[0051] like Figure 4 As shown, in some specific embodiments, the catalytic bed 4 includes a catalytic tube 41, a catalytic body 42 and a catalytic cover plate 43. An open end of the catalytic tube 41 is connected to an open end of the second combustion tube 2 away from the first combustion tube 1 through a flange; the catalytic body 42 is placed in the catalytic tube 41; and the catalytic cover plate 43 is fixed to the other open end of the catalytic tube 41 away from the second combustion tube 2.

[0052] The rate at which solid fuels pyrolyze is called the burning rate. The unit is mm / s. The shape of the second layer of fuel is the same as the shape of the first layer of fuel when it is burned out according to the parallel layer combustion law. In theory, the engine will have two independent working stages, and the combustion of the two layers of fuel will not affect each other, which simplifies the difficulty of design and simulation. The internal ballistic performance of solid-liquid rocket engines is an important parameter of solid-liquid rocket engines. It can be measured through experiments. In order to simplify the design process, numerical simulation methods are usually used to obtain it in the preliminary design process of actual engineering. Specifically:

[0053] Step 1: Perform numerical simulation of the flow field inside a solid-liquid rocket engine [3] to obtain the burning rate formula of the side burning surface and engine specific impulse efficiency η Is.in is the burning rate of the burning surface, a and n are constants related only to the propellant, G o is the oxidant flow rate, calculated as The corresponding channel area A o Ratio In this example, considering the specific impulse efficiency to be 90%, it can be obtained by dividing the simulation result with the theoretical value obtained by the RPA software thermal calculation. It can also be estimated from previous test experience. When the combustion of the front and rear end surfaces of the grain is ignored, the burning rate formula is as follows:

[0054] Table 3 Burning rate formula

[0055]

[0056] Step 2: Calculate the engine internal ballistics based on the burning rate formula and specific impulse efficiency [4], using the zero-dimensional internal ballistics assumption, the instantaneous equilibrium pressure method and the parallel layer combustion theorem. The engine internal ballistics calculation technology is relatively mature at present, so I will not elaborate on it in detail. The purpose of the internal ballistics calculation is to finally obtain the curves of the combustion chamber pressure and thrust over time during the engine operation process, that is, the pc-t and Ft curves. At the same time, other key parameters can also be obtained, such as fuel flow, engine oxygen-fuel ratio O / F, etc.

[0057] Figure 7 This is the engine sea level thrust curve obtained through interior ballistic calculation. The results show that the star-shaped double-layer solid-liquid rocket engine has obvious two-stage thrust. The initial thrust of the engine is 535N, the average thrust of the second stage is 410N, and it also has multiple start-stop functions.

[0058] The oxygen-fuel ratio is a crucial design parameter for rocket engines, which greatly affects the performance of the engine. The deviation from the optimal oxygen-fuel ratio during the operation of solid-liquid rocket engines will lead to a significant performance degradation, mainly manifested in a reduction in specific impulse, which means that more propellant is required to produce the same thrust, which is not conducive to giving full play to the advantages of variable thrust and high specific impulse of solid-liquid rocket engines, and greatly restricts their development.

[0059] Figure 8 This is the oxygen-fuel ratio distribution diagram of the engine working process. Except for the residual charge stage, the two stages of the engine work near the theoretical optimal oxygen-fuel ratio, which can meet the requirements for high performance.

[0060] like Figure 4 As shown, in some specific embodiments, the seal head 5 may include a seal tube 51, and an open end of the seal tube 51 is fixed to the open end of the third combustion tube 3 away from the first combustion tube 1 through a flange.

[0061] like Figure 4As shown, in some specific embodiments, the sealing head 5 may further include an annular sealing head insulation layer 52 , and the annular sealing head insulation layer 52 is penetrated and fixed on the inner cylinder wall of the sealing cylinder 51 .

[0062] like Figure 4 As shown, in some specific embodiments, a nozzle 11 and a pressure plate 12 may also be included. The nozzle 11 is inserted into the sealing tube 51 ; the pressure plate 12 is fixed to the opening end of the sealing tube 51 away from the third combustion tube 3 and fixed on the nozzle 11 .

[0063] In some specific embodiments, the nozzle 11 may be a tungsten-copper-infiltrated Laval nozzle.

[0064] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A star-shaped double-layer solid-liquid rocket engine, characterized in that: include: A first combustion tube (1), wherein a first star-shaped fuel layer (6), a second star-shaped fuel layer (7) and a first annular heat-insulating layer (8) are cast in sequence from the inside to the outside of the first combustion tube (1), and the first star-shaped fuel layer (6) has a charge column inner channel inside; A second combustion tube (2) and a third combustion tube (3), wherein the second combustion tube (2) and the third combustion tube (3) are respectively connected to two open ends of the first combustion tube (1) through flanges; A catalytic bed (4), wherein the catalytic bed (4) is fixed to an open end of the second combustion tube (2) away from the first combustion tube (1) via a flange; A sealing head (5) is fixed to an open end of the third combustion tube (3) away from the first combustion tube (1) through a flange.

2. A star-shaped double-layer solid-liquid rocket engine according to claim 1, characterized in that: The cross-sections of the first star-shaped fuel layer (6) and the second star-shaped fuel layer (7) are both six-star structures.

3. A star-shaped double-layer solid-liquid rocket engine according to claim 1, characterized in that: The first star-shaped fuel layer (6) is made of 40% to 60% butyl hydroxy fuel, 30% to 50% aluminum and 5% to 15% octogold; the second star-shaped fuel layer (7) is made of 65% to 75% butyl hydroxy fuel and 25% to 55% aluminum.

4. A star-shaped double-layer solid-liquid rocket engine according to claim 1, characterized in that: A second annular heat insulating layer (9) is fixed on the inner wall of the second combustion tube (2), and a third annular heat insulating layer (10) is fixed on the inner wall of the third combustion tube (3).

5. A star-shaped double-layer solid-liquid rocket engine according to claim 1, characterized in that: The catalytic bed (4) comprises a catalytic tube (41), a catalytic body (42) and a catalytic cover plate (43); an open end of the catalytic tube (41) is connected to an open end of the second combustion tube (2) away from the first combustion tube (1) through a flange; the catalytic body (42) is placed in the catalytic tube (41); and the catalytic cover plate (43) is fixed to the other open end of the catalytic tube (41) away from the second combustion tube (2).

6. A star-shaped double-layer solid-liquid rocket engine according to claim 1, characterized in that: The sealing head (5) comprises a sealing tube (51), an open end of which is fixed to an open end of the third combustion tube (3) away from the first combustion tube (1) via a flange.

7. A star-shaped double-layer solid-liquid rocket engine according to claim 6, characterized in that: The sealing head (5) further comprises an annular sealing head heat insulation layer (52), and the annular sealing head heat insulation layer (52) is penetrated and fixed on the inner cylinder wall of the sealing cylinder (51).

8. A star-shaped double-layer solid-liquid rocket engine according to claim 6, characterized in that: It also comprises a nozzle (11) and a pressure plate (12), wherein the nozzle (11) is inserted into the sealing tube (51); the pressure plate (12) is fixed to the opening end of the sealing tube (51) away from the third combustion tube (3) and is fixed to the nozzle (11).

9. A star-shaped double-layer solid-liquid rocket engine according to claim 8, characterized in that: The nozzle (11) is a tungsten-copper-infiltrated Laval nozzle.

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