Air suction type space thruster and specific impulse optimization method thereof

Abstract

The invention provides an air suction type space thruster and a specific impulse optimization method thereof. The thruster comprises an oxygen and air mixed supply module, a catalytic chamber, a flame arrester, a combustion chamber and a spray pipe. The specific impulse optimization method comprises the following steps: 1) setting an initial oxygen / fuel mass ratio e1 introduced into the air-breathing space thruster; (2) air is introduced into the oxygen introduced into the air-breathing space thruster, so that the oxygen concentration is reduced; (3) controlling the total flow of the propellant, namely the total mass flow of the oxidant and the fuel to be stable before plugging or under the plugging condition; 4) measuring the thrust of the air-breathing space thruster through the test platform, and calculating a test specific impulse and a theoretical specific impulse which do not consider the air quality; and (5) according to the change of the specific impulse of the thruster along with the oxygen concentration, the corresponding oxygen concentration, namely the oxygen and air flow ratio, when the specific impulse is high is obtained. The oxygen concentration in the oxidizing agent is adjusted by introducing rarefied air, the specific impulse performance of the thruster is improved under the condition that the fuel flow is not changed, and therefore the overall propelling efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aerospace propulsion technology, in particular to an air-breathing space thruster and a specific impulse optimization method thereof. BACKGROUND

[0002] In the near space (airspace 20-100 km from the ground), the atmosphere is thin but still contains available oxygen components, which has certain air-breathing propulsion potential. However, the traditional small rocket or micro-propulsion system generally adopts a closed propulsion mode, which needs to carry all the oxidants, which not only greatly increases the system load, but also limits the flight time, maneuverability and task efficiency of the high-altitude platform in the near space. Especially in the ultra-small aircraft, micro-satellite and high-altitude platform, the weight and efficiency bottleneck of the traditional propulsion system becomes the key limiting factor for application expansion.

[0003] Air-breathing propulsion technology can collect oxygen in the environment air for reaction with fuel, thereby reducing the amount of oxidant carried, effectively reducing the total mass of the propulsion system and improving the specific impulse. However, existing researches are mostly focused on turbojet or ramjet engines under high-speed flight conditions, and the research on air-breathing micro-thrusters suitable for low-speed, micro-scale platforms in the near space is still relatively weak.

[0004] The existing technology has low utilization efficiency of the thin air as the oxidant, lacks systematic research on the influence of environmental oxygen concentration changes on the combustion stability, flame behavior and jet flow state, and especially lacks theoretical modeling and experimental verification of the specific impulse variation law under different jet working conditions. Because the oxygen content in the air is limited and changes significantly with altitude, the air mixing process is easy to cause flame instability, thrust fluctuation and other problems, which seriously affect the reliability and efficiency of the system operation. In addition, the existing technology does not effectively analyze and design the adaptability of various propellant combinations under air-breathing conditions, which limits the generality and practicability of the technology.

[0005] Therefore, there is an urgent need for an air-breathing thruster system that can introduce air in the near space environment and realize oxygen concentration regulation, and a specific impulse optimization method system is needed to break through the bottleneck of traditional propulsion technology in the low-density environment at high altitude, and to promote the practical application of small-sized, light-weight and high-efficiency propulsion devices in the near space. SUMMARY

[0006] In view of the technical problems in the above background art, the present application provides an air-breathing space thruster and a specific impulse optimization method thereof, which adjusts the oxygen concentration in the oxidant by introducing thin air, improves the specific impulse performance of the thruster without changing the fuel flow rate, and thus improves the overall propulsion efficiency.

[0007] To solve the above-mentioned technical problems, the present invention provides an air-breathing space thruster, including a combustion chamber and a nozzle disposed at the exhaust gas outlet of the combustion chamber; the thruster also includes an oxygen and air mixing supply module, a catalytic chamber and a flame arrester;

[0008] The oxygen and air mixing supply module is used to precisely control the mixing ratio of oxygen and air. It includes a mixing chamber and a premixing chamber. The input end of the mixing chamber is respectively introduced into gaseous fuel and gaseous oxidant, and is also matched and connected to the output end of the premixing chamber. The input end of the premixing chamber is connected to a rarefied air collection device.

[0009] The catalyst chamber is matched and installed at the output end of the premixing chamber and is filled with catalyst; flame arresters are also matched at the front and rear positions of the inner cavity of the catalyst chamber.

[0010] The combustion chamber is matched and installed at the output end of the catalytic chamber, and a connecting section shell is also matched and fitted at the connection between the combustion chamber and the catalytic chamber;

[0011] A central tube is axially inserted through the center of the inner cavity of the catalytic chamber; one end of the central tube passes through the flame arrester and the output end of the catalytic chamber in sequence and extends into the premixing chamber to match and connect with the input end of the premixing chamber for gaseous fuel; the other end of the central tube extends out of the output end of the catalytic chamber and passes through the connecting section shell to match and connect with the air inlet of the combustion chamber; and an annular gap is left between the circumferential outer wall of the central tube and the catalytic chamber, the flame arrester, and the connecting section shell.

[0012] The air-breathing space thruster, wherein the oxygen and air mixing supply module further includes a first electromagnetic check valve;

[0013] The input end of the mixing chamber is provided with a first mixing inlet, a second mixing inlet, and a mixing outlet; the first electromagnetic check valve is matched and installed in the second mixing inlet;

[0014] The input end of the premixing chamber is respectively provided with a first premixing inlet that is matched and connected to the mixing outlet of the mixing chamber, a second premixing inlet for receiving gaseous fuel output from the fuel supply system, and a third premixing inlet for receiving gaseous oxidant.

[0015] The air-breathing space thruster includes an air outlet of the rarefied air capture device that is connected to the first mixing air inlet via an air duct, and a second electromagnetic one-way valve is also installed inside the air outlet of the rarefied air capture device.

[0016] A method for optimizing the specific impulse of an air-breathing space thruster, comprising the following steps:

[0017] 1) Set the initial oxygen / fuel mass ratio e1 for the air-breathing space thruster;

[0018] 2) Introduce air into the oxygen supply to the air-breathing space thruster to reduce the oxygen concentration;

[0019] 3) Control the total propellant flow rate, i.e. the total mass flow rate of oxidizer and fuel, to be stable before or under clogging conditions;

[0020] 4) Measure the thrust of the air-breathing space thruster using a test platform, and calculate the experimental specific impulse and theoretical specific impulse without considering air quality;

[0021] 5) Based on the change of thrust specific impulse with oxygen concentration, the oxygen concentration corresponding to a higher specific impulse, i.e., the oxygen and air flow ratio, can be obtained.

[0022] The specific impulse optimization method for the air-breathing space thruster, wherein in step 1), when the initial oxygen / hydrogen mass ratio is set to e1, the air supply is... The oxygen mass fraction in the oxidant is e2, and the corresponding oxygen concentration is:

[0023] w o2 =e2ρ mix / ρ O2 ;

[0024] In the above formula, w o2 For oxygen concentration, ρ mix and ρ O2 Let the densities of the oxidant and oxygen be denoted as , respectively; the mass fraction of oxygen in the air is 0.233. Establish the mass balance equation:

[0025]

[0026] After sorting, we can obtain:

[0027]

[0028] The specific impulse optimization method for the air-breathing space thruster, wherein, after introducing air into the oxygen in step 2), the ratio of the total propellant mass to the initial mass is:

[0029]

[0030] The specific impulse optimization method for the air-breathing space thruster, wherein: the air in step 2) is not carried by the thruster itself, therefore, in step 4), the air mass is not taken into account when calculating the specific impulse, the experimental specific impulse I is calculated. ss for:

[0031]

[0032] Then, after adding air, the theoretical specific impulse I calculated using thermodynamic formulas is... s Multiply by coefficient k m The theoretical specific impulse I is obtained without considering air quality. ssp :

[0033] I ssp =I s j m (5);

[0034] During thrust testing on the test platform, the total mass flow rate of fuel and oxygen was initially maintained at [value missing]. Set a fixed initial oxygen / fuel mass ratio e1; after successful ignition of the air-breathing space thruster, gradually add air to the oxygen to form oxidants with different oxygen concentrations, measure the corresponding thrust, and calculate the test specific impulse using formula (4); repeat the above test process by adjusting different initial oxygen / fuel mass ratios.

[0035] By adopting the above technical solution, the present invention has the following beneficial effects:

[0036] The specific impulse optimization method for the air-breathing space thruster of this invention is reasonably conceived. By introducing rarefied air to adjust the oxygen concentration in the oxidizer, the specific impulse performance of the thruster is improved without changing the fuel flow rate, thereby increasing the overall propulsion efficiency. Specific advantages are reflected in the following aspects:

[0037] (1) Improve specific impulse and propulsion efficiency

[0038] This invention optimizes the specific impulse by introducing rarefied air to regulate the oxygen concentration in the oxidizer, without increasing the total propellant mass or changing the fuel flow rate. This significantly improves the effective thrust generated per unit mass of propellant in the thruster, thereby enhancing the combustion efficiency of the propulsion system and the energy utilization efficiency of the flight mission.

[0039] (2) Reduce system load and extend task time

[0040] Since some of the oxidant comes from the rarefied air in near space, the reliance on high-purity oxygen is reduced, thereby lowering the system's need for heavy oxygen storage equipment, reducing the overall weight of the aircraft, and helping to improve the payload capacity of the flight platform or extend mission endurance.

[0041] (3) Adapt to complex and ever-changing environments and expand the scope of application.

[0042] This invention is applicable to special environments such as high altitude and near space where oxygen concentration is low. It can meet the working requirements of various aircraft such as micro spacecraft, small drones, and high-altitude servo platforms in thin air environments, achieve stable combustion and efficient propulsion, and has good environmental adaptability and scalability.

[0043] (4) Support for complete air oxygen supply under hydrogen system

[0044] The method of the present invention can provide all the oxygen source in a hydrogen fuel system through air (or a dilute oxidant), avoiding the safety hazards such as excessive oxidation and local detonation that may be caused by a high oxygen concentration environment, and improving the safety and stability of the system.

[0045] (5) Possesses good system compatibility and engineering feasibility.

[0046] This solution does not require complex modifications to the existing thruster structure and can be flexibly integrated into traditional gas thrusters or new small propulsion systems. It has good engineering adaptability and deployment feasibility, and is suitable for promotion and application in existing or next-generation flight platforms.

[0047] (6) Enhance task autonomy and resource utilization

[0048] By utilizing part of the surrounding ambient air, the propulsion system gains a stronger self-sufficiency in resources, reducing reliance on ground resupply and providing technical support for future aerospace systems with autonomous combat and detection capabilities.

[0049] (7) Innovative methods for oxygen concentration regulation

[0050] This invention proposes a novel approach to oxidizer oxygen concentration control, which can flexibly adjust the oxygen supply ratio according to different mission requirements and optimize the combustion process. It is an innovative combustion organization method for the special propulsion needs of near space, and has significant innovation and technological foresight.

[0051] (8) Significantly improve the overall performance indicators of the system

[0052] While achieving a specific impulse increase, this invention can also take into account multiple indicators such as combustion stability, system thermal management, and environmental adaptability. It achieves comprehensive optimization among multiple objectives such as thrust, energy efficiency, and adaptability, and its overall technical advantages are significantly better than those of traditional fixed oxygen concentration propulsion systems. Attached Figure Description

[0053] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0054] Figure 1 This is a schematic diagram of the structure of the air-breathing space thruster of the present invention;

[0055] Figure 2This is a schematic diagram of the thrust testing device.

[0056] Figure 3 The graph shows the variation of the experimental and theoretical specific impulse of the thruster before nozzle congestion with the initial oxygen / fuel mass ratio, which is related to the specific impulse optimization method of the air-breathing space thruster of the present invention.

[0057] Figure 4 This is a graph showing the variation of experimental and theoretical specific impulse with oxygen concentration under the nozzle clogging state of the thruster involved in the specific impulse optimization method of the air-breathing space thruster of the present invention. Detailed Implementation

[0058] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] The present invention will be further explained below with reference to specific embodiments.

[0060] like Figure 1 As shown, this embodiment provides an air-breathing space thruster, including an oxygen and air mixing supply module 1, a rarefied air capture device 2, a catalytic chamber 3, a flame arrester 4, a combustion chamber 5, a nozzle 6, and a central tube 7.

[0061] The oxygen and air mixing supply module 1 is used to precisely control the mixing ratio of oxygen and air. It includes a mixing chamber 11, a first electromagnetic check valve 12, and a premixing chamber 13. The mixing chamber 11 is equipped with a first mixing inlet 111, a second mixing inlet 112, and a mixing outlet. The first electromagnetic check valve 12 is installed inside the second mixing inlet 112. The premixing chamber 13 has a first premixing inlet 131 and a second premixing inlet 132 on its radially opposite sides, and a third premixing inlet 133 on one axial end. The first premixing inlet 131 is connected to the mixing outlet of the mixing chamber 11 through a ventilation pipe. The second premixing inlet 132 is used to receive gaseous fuel output from a fuel supply system (such as hydrogen or methane), and the third premixing inlet 133 is used to receive gaseous oxidant. After the gaseous fuel and gaseous oxidant are fully mixed, a fuel-rich or fuel-lean mixture is formed.

[0062] The outlet of the rarefied air capture device 2 is connected to the first mixing inlet 111 of the mixing chamber 11 via a ventilation pipe, and a second electromagnetic one-way valve 21 is also installed inside the outlet of the rarefied air capture device 2. The rarefied air capture device 2 is used to actively capture rarefied air from near-space or high-altitude environments during flight, serving as a partial source of oxidant. Through a rationally arranged inlet structure, combined with the ram effect generated by the aircraft's motion, the rarefied air capture device 2 guides ambient air to the inlet, and connects it to the first mixing inlet 111 of the mixing chamber 11 via a ventilation pipe, thereby mixing air with oxidant components such as high-purity oxygen and adjusting the oxygen concentration in the mixed gas. The specific functions of this rarefied air capture device 2 include: partially replacing the oxidizer, that is, using the rarefied air from outside as an auxiliary oxidizer to reduce the need for carrying high-purity oxygen, thereby reducing the overall burden on the system; regulating oxygen concentration, that is, mixing it with high-purity oxygen in a certain proportion to flexibly control the oxygen concentration of the oxidizer, optimize combustion conditions, and improve specific impulse performance; enhancing the adaptability of the propulsion system, especially suitable for special environments such as near space and rarefied air, expanding the application range of the system; improving the efficiency and endurance of the propulsion system, that is, improving the energy efficiency ratio and resource utilization rate of the propulsion system through "on-site" air utilization; and enhancing the safety and stability of the system, that is, reducing the pure oxygen concentration, reducing the risk of deflagration, and making the combustion process more gentle and controllable. In addition, to achieve precise control of air intake, a second electromagnetic check valve 21 is installed in the outlet of the rarefied air capture device 2. The second electromagnetic check valve 21 is used to prevent reverse airflow from entering the rarefied air capture device 2, ensuring one-way air supply; it enables electronic control adjustment of the amount of air intake, which can be opened or closed as needed, which is beneficial for dynamic control of the mixing ratio; and it works with the control system to manage the time-sharing air supply during the flight phase, for example, automatically opening during the high-altitude flight phase and closing during the ground or oxygen-sufficient phase, ensuring that the thruster operates in the optimal mode.

[0063] The catalytic chamber 3 is matched and installed at the output end of the premixing chamber 13 of the oxygen and air mixing supply module 1; the catalytic chamber 3 is filled with a catalyst with a high catalytic effect. A flame arrester 4 is provided at the front and rear positions of the catalytic chamber 3 (in this embodiment, the flame arrester 4 is located in the inner cavity of the catalytic chamber 3 near the premixing chamber 13). The flame arrester 4 mainly functions to support the catalyst and prevent backfire. The fuel-rich or fuel-lean mixture undergoes a catalytic reaction on the catalyst surface, and the high-temperature gas leaving the catalytic chamber 3 mainly consists of combustion products and unreacted gaseous fuel or gaseous oxidant.

[0064] The combustion chamber 5 is matched and installed at the output end of the catalytic chamber 3. The connection between the combustion chamber 5 and the catalytic chamber 3 is also matched and fitted with a connecting section shell 51. The exhaust gas outlet of the combustion chamber 5 is matched and installed with a nozzle 6.

[0065] The central tube 7 runs through the center of the inner cavity of the catalytic chamber 3. One end of the central tube 7 passes through the flame arrester 4, extends out of the axial side of the catalytic chamber 3, and enters the premixing chamber 13, connecting with the third premixing inlet 133 of the premixing chamber 13. The other end of the central tube 7 extends out of the axial side of the catalytic chamber 3, passes through the connecting section shell 51, and connects with the gas inlet of the combustion chamber 5. An annular gap is formed between the outside of the central tube 7 and the catalytic chamber 3, the flame arrester 4, and the connecting section shell 51. Gaseous fuel enters the catalytic chamber 3 through the central tube 31. The high-temperature gas discharged after catalytic combustion in the catalytic chamber 3 is mainly combustion products and gaseous oxidant, and enters the combustion chamber 5 through the annular gap surrounding the central tube 31, which is a conventional diffusion combustion organization method. In the combustion chamber 5, the high-temperature gas after catalytic combustion meets and burns with the gaseous oxidant or gaseous fuel jet in the central tube 31, forming a coaxial diffusion flame. Subsequently, the high-temperature products after combustion are ejected through the nozzle 6 at the exhaust outlet of the combustion chamber 5, generating thrust.

[0066] The test platform 7 is used to measure the air-breathing space thruster of the present invention (i.e., Figure 2 The thrust of A) includes an electronic balance 71 and a bracket 72 matched and disposed on the upper part of the electronic balance 71; the bracket 72 is used to install the air-breathing space thruster of the present invention.

[0067] The specific impulse optimization method for an air-breathing space thruster of the present invention specifically includes the following steps:

[0068] (1) Set the initial oxygen / fuel mass ratio e1 for the air-breathing space thruster;

[0069] (2) Introduce air into the oxygen supplied to the air-breathing space thruster to reduce the oxygen concentration;

[0070] (3) Control the total propellant flow rate, i.e. the total mass flow rate of oxidizer and fuel, to be stable before or under clogging conditions;

[0071] (4) Measure the thrust of the air-breathing space thruster through the test platform (7) and calculate the test specific impulse and theoretical specific impulse without considering air quality;

[0072] (5) Based on the change of thrust specific impulse with oxygen concentration, the oxygen concentration corresponding to a higher specific impulse, i.e. the oxygen and air flow ratio, can be obtained.

[0073] Before the thruster nozzle becomes congested, the introduction of air has two main effects: firstly, changes in flame temperature can increase (in oxygen-deficient) or decrease (in oxygen-enriched) thrust; secondly, an increase in the total propellant flow rate can improve thrust. The relative interaction of these two factors determines the thruster's performance. Taking a hydrogen / oxygen thruster as an example, the calculation process for theoretical specific impulse is illustrated, with the initial oxygen / hydrogen mass ratio being e1 (i.e.,... The air supply is At this point, the mass fraction of oxygen in the oxidant is e2, and the corresponding oxygen concentration is given by the formula w. o2 =e2ρ mix / ρ O2 ρ was calculated to be... mix and ρ O2 Let the densities of the oxidant and oxygen be denoted as . The mass fraction of oxygen in the air is 0.233. Establish the mass balance equation:

[0074]

[0075] After sorting, we can obtain:

[0076]

[0077] The ratio of the total mass of the propellant after adding air to the initial mass is:

[0078]

[0079] Considering that the air in step 2) is not carried by the thruster itself, in step 4), the air mass is not taken into account when calculating the specific impulse, so the experimental specific impulse I is calculated. ss for:

[0080]

[0081] The theoretical specific impulse I calculated using thermodynamic formulas after adding air s It needs to be multiplied by a coefficient k m The theoretical specific impulse I is obtained without considering air quality. ssp :

[0082] I ssp =I s k m (5);

[0083] During thrust testing on test platform 7, the total mass flow rate of fuel and oxygen was initially maintained at [value missing]. A fixed initial oxygen / fuel mass ratio e1 is established. After successful thrust ignition, air is gradually added to the oxygen to form oxidants with different oxygen concentrations. The corresponding thrust is measured, and the test specific impulse is calculated using formula (4). The above test process is repeated by adjusting different initial oxygen / fuel mass ratios.

[0084] When the nozzle 6 of the thruster reaches a choked state, the flow rate of the fluid flowing through the throat of the nozzle 6 can no longer increase. Under the condition that the total propellant flow rate and fuel flow rate remain unchanged, the flow ratio of air and oxygen is changed to obtain different oxygen concentrations. The thrust of the thruster prototype is tested to obtain the experimental specific impulse. The theoretical specific impulse is calculated by the above method.

[0085] In this embodiment, usingFigure 1 The thruster shown underwent thrust testing. Initially, the total mass flow rate of fuel and oxygen was 0.05 g / s, and an initial oxygen / fuel mass ratio e1 was fixed. After successful thruster ignition, ambient air was introduced into the oxygen delivery path. The air valve was adjusted to gradually decrease the oxygen mass fraction of the mixed oxidizer, thereby controlling the flame temperature and nozzle velocity. Figure 2 The thrust measuring device shown measures the thrust under different operating conditions. Substituting this into Formula 4, the test specific impulse can be calculated. The above test process is repeated by adjusting different initial oxygen / fuel mass ratios.

[0086] Figure 3 The figure shows the variation of the experimental specific impulse with the initial oxygen / fuel mass ratio under different oxygen concentrations. The theoretical specific impulse curve calculated by formula 5 is also given in the figure, indicating that the theoretical calculation and the experimental results show a consistent variation pattern. Figure 3 (a) and Figure 3 (b) Test results for hydrogen / oxygen thrusters and methane / oxygen thrusters, respectively. Although changes in oxygen concentration alter the jet flame height and may cause the thruster length to deviate from optimal operating conditions, the test results show that the effect of air addition on the thruster's specific impulse is relatively clear: at a given initial oxygen / fuel mass ratio, the specific impulse increases with increasing air flow rate.

[0087] Under choked conditions, the fluid flow rate through the throat of nozzle 6 cannot continue to increase, within the total propellant flow rate (hydrogen / oxygen thruster: Methane / Oxygen Thruster: ) and fuel flow ( Under constant conditions, by changing the flow rate ratio of air and oxygen to obtain different oxygen concentrations, thrust tests were conducted on the prototype thruster to obtain experimental specific impulse. The theoretical specific impulse was then calculated using the method described above, and the results are as follows: Figure 4 As shown.

[0088] The theoretical calculations and test results show good agreement on their trends. The experimental specific impulse increases exponentially with decreasing oxygen concentration in the oxidant. For the hydrogen / oxygen thruster, the following fit is obtained based on the experimental data: For methane / oxygen thrusters In general, in-situ air can improve the specific impulse of the thruster. For hydrogen / oxygen thrusters, the hydrogen flame can remain stable in both air and oxygen, and even air can be used entirely as the oxidant to obtain a higher specific impulse. For methane / oxygen thrusters, the effect of changes in oxygen concentration on flame behavior, especially its stability, needs to be considered. For example, if the flame is blown out when the oxygen concentration is less than 30%, the thruster cannot work properly during the test.

[0089] This invention improves the specific impulse of the thruster without changing the fuel flow rate by introducing rarefied air to regulate the oxygen concentration in the oxidizer, thereby increasing the overall propulsion efficiency.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An air-breathing space thruster, comprising a combustion chamber (5) and a nozzle (6) disposed at the exhaust outlet of the combustion chamber (5); characterized in that: The thruster also includes an oxygen and air mixing supply module (1), a catalytic chamber (3), and a flame arrester (4); The oxygen and air mixing supply module (1) is used to precisely control the mixing ratio of oxygen and air. It includes a mixing chamber (11) and a premixing chamber (13). The input end of the mixing chamber (11) is respectively supplied with gaseous fuel and gaseous oxidant, and is also matched and connected to the output end of the premixing chamber (13). The input end of the premixing chamber (13) is connected to a rarefied air collection device (2). The catalyst chamber (3) is matched and installed at the output end of the premix chamber (13) and is filled with catalyst; flame arresters (4) are also matched and installed at the front and rear positions of the inner cavity of the catalyst chamber (3); The combustion chamber (5) is matched and installed at the output end of the catalytic chamber (3), and a connecting section shell (51) is also matched and fitted at the connection between the combustion chamber (5) and the catalytic chamber (3); A central tube (7) is axially inserted through the center of the inner cavity of the catalytic chamber (3); one end of the central tube (7) passes through the flame arrester (4) and the output end of the catalytic chamber (3) in sequence and extends into the premixing chamber (13) to match and connect with the input end of the premixing chamber (13) for gas fuel; the other end of the central tube (31) extends out of the output end of the catalytic chamber (3) and passes through the connecting section shell (51) to match and connect with the air inlet of the combustion chamber (5); and an annular gap is left between the circumferential outer wall of the central tube (7) and the catalytic chamber (3), the flame arrester (4), and the connecting section shell (51).

2. The air-breathing space thruster as described in claim 1, characterized in that: The oxygen and air mixing supply module (1) also includes a first electromagnetic check valve (12); The mixing chamber (11) has a first mixing inlet (111), a second mixing inlet (112), and a mixing outlet at its input end; the first electromagnetic check valve (12) is installed in the second mixing inlet (112); The input end of the premixing chamber (13) is provided with a first premixing inlet (131) that is matched and connected to the mixing outlet of the mixing chamber (11), a second premixing inlet (132) for connecting the gaseous fuel output by the fuel supply system, and a third premixing inlet (133) for connecting the gaseous oxidant.

3. The air-breathing space thruster as described in claim 1, characterized in that: The outlet of the rarefied air collection device (2) is connected to the first mixing inlet (111) through an air pipe, and a second electromagnetic check valve (21) is also installed in the outlet of the rarefied air collection device (2).

4. A method for optimizing the specific impulse of an air-breathing space thruster based on any one of claims 1-3, characterized in that, Includes the following steps: 1) Set the initial oxygen / fuel mass ratio e1 for the air-breathing space thruster; 2) Introduce air into the oxygen supply to the air-breathing space thruster to reduce the oxygen concentration; 3) Control the total propellant flow rate, i.e. the total mass flow rate of oxidizer and fuel, to be stable before or under clogging conditions; 4) Measure the thrust of the air-breathing space thruster through the test platform (7) and calculate the test specific impulse and theoretical specific impulse without considering air quality; 5) Based on the change of thrust specific impulse with oxygen concentration, the oxygen concentration corresponding to a higher specific impulse, i.e., the oxygen and air flow ratio, can be obtained.

5. The specific impulse optimization method for an air-breathing space thruster as described in claim 4, characterized in that, In step 1), when the initial oxygen / hydrogen mass ratio is set to e1, the air supply is... The oxygen mass fraction in the oxidant is e2, and the corresponding oxygen concentration is: w o2 =e2ρ mix / r O2 ; In the above formula, w o2 For oxygen concentration, ρ mix and ρ O2 Let the densities of the oxidant and oxygen be denoted as , respectively; the mass fraction of oxygen in the air is 0.

233. Establish the mass balance equation: After sorting, we can obtain:

6. The specific impulse optimization method for an air-breathing space thruster as described in claim 4, characterized in that, After introducing air into the oxygen in step 2), the ratio of the total propellant mass to the initial mass is:

7. The specific impulse optimization method for an air-breathing space thruster as described in claim 4, characterized in that: The air in step 2) is not carried by the thruster itself; therefore, in step 4), the air mass is not taken into account when calculating the specific impulse, and the experimental specific impulse I is calculated. ss for: Then, after adding air, the theoretical specific impulse I calculated using thermodynamic formulas is... s Multiply by coefficient k m The theoretical specific impulse I is obtained without considering air quality. ssp : I ssp =I s k m (5); When conducting thrust tests on the test platform (7), the total mass flow rate of fuel and oxygen is first maintained at a certain value. Set a fixed initial oxygen / fuel mass ratio e1; after successful ignition of the air-breathing space thruster, gradually add air to the oxygen to form oxidants with different oxygen concentrations, measure the corresponding thrust, and calculate the test specific impulse using formula (4); repeat the above test process by adjusting different initial oxygen / fuel mass ratios.

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