Needle bolt injection type engine combustion simulation method and system

Abstract

The invention belongs to the technical field of liquid-propelled rocket engines, and relates to a pintle injection type engine combustion simulation method, which comprises the following steps of: 1, establishing a pintle injection type engine computational domain, and dividing grids; 2, carrying out cold-state jet atomization numerical simulation on the pintle injection type engine, and counting particle information of atomized liquid drops; 3, taking particle information counted in cold-state numerical simulation as an input condition, and coupling the input condition to hot-state combustion numerical simulation; 4, exporting a combustion numerical simulation result of the pintle injection type engine, and performing post-processing analysis; the invention further discloses a pintle injection type engine combustion simulation system. According to the invention, particle information of cold-state jet atomization simulation is extracted and indirectly coupled to hot-state combustion simulation, so that the working continuity and accuracy of pintle injection type engine whole-process simulation are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of liquid-propellant rocket engines and relates to a pintle injection engine combustion simulation method and system. Background Art

[0002] Pintle injectors are key components in liquid rocket engines, primarily responsible for propellant atomization, mixing, and combustion control. Their core structure consists of a pintle (a movable, adjustable component) and an annular injection channel. Adjusting the pintle position changes the injection area, thereby precisely controlling the propellant flow rate and mixing ratio. Pintle injectors are widely used in variable-thrust, attitude, and trajectory control vehicles due to their excellent thrust regulation, ease of manufacturing, and high operational reliability.

[0003] The traditional pintle injection engine development process requires multiple test runs and optimization, resulting in long development cycles and high costs. Therefore, developing efficient and reliable combustion simulation technology to accurately predict the combustion properties of pintle injection engines is crucial. Optimizing pintle injection engine component configuration and combustion structure through numerical simulation can shorten development cycles and reduce R&D costs.

[0004] In addition, the pintle injection engine has unique combustion characteristics. It is affected by many factors such as the typical "double recirculation" flow field structure and the atomization effect. There is a regulatory contradiction between efficient combustion and wall cooling. The objective conditions of high combustion room and low pressure make it difficult to implement visualization experiments. There is a lack of numerical prediction methods for combustion performance, which limits the development of the pintle injection engine.

[0005] Therefore, a method or device is needed to solve the above technical problems by reducing the number of test cycles, saving R&D costs and performing preliminary selection optimization. Summary of the Invention

[0006] The technical solution adopted by the present invention to solve the technical problem is: a pintle injection engine combustion simulation method, comprising the following steps:

[0007] Step 1: Establish the computational domain of the pintle injection engine and divide the grid;

[0008] Step 2: numerically simulate the cold jet atomization of the pintle injection engine and calculate the particle information of the atomized droplets;

[0009] Step 3: The particle information collected in the cold state numerical simulation is coupled to the hot state combustion numerical simulation as input conditions;

[0010] Step 4: Export the combustion numerical simulation results of the pintle injection engine and perform post-processing analysis.

[0011] Preferably, in step 1, the calculation domain is constructed based on the fluid space contained in the inner wall of the specific pintle injection engine, and the calculation domain covers the entire area of the propellant jet atomization and combustion flow process.

[0012] Preferably, the step 2 specifically includes: performing a fluid volume method-large eddy simulation calculation on the example pintle jet injection flow atomization, the fluid volume method-large eddy simulation calculation includes: setting the inlet flow boundary conditions according to the engine example, using the fluid volume method to calculate the two-phase interface, using large eddy simulation to calculate the turbulence development, and using the PIMPLE method to iteratively calculate various numerical values.

[0013] More preferably, in step 2, after iteratively calculating various values using the PIMPLE method, the calculation results are extracted and analyzed to statistically calculate the velocity, particle size, mass, and spatial distribution position information of the droplet particles.

[0014] Preferably, in step 3, a numerical simulation of pintle injection engine combustion is carried out by coupling the eddy dissipation conceptual model with the simplified multi-step reaction mechanism of each reaction and each component, and the design operating conditions are calculated based on the particle data as the propellant input parameters.

[0015] Preferably, in step 4, the combustion numerical simulation results include: temperature, pressure, velocity, key reaction components, and droplet spatial distribution of the pintle injection engine.

[0016] The present invention further discloses a pintle injection engine combustion simulation system, which is used to execute the above-mentioned pintle injection engine combustion simulation method. The combustion simulation system includes:

[0017] The model building module is used to establish the computational domain of the pintle injection engine and construct a numerical model for indirect coupling between cold and hot states;

[0018] Numerical calculation module, used for numerical calculation of pintle injection engine simulation, including particle information of cold jet atomization and hot combustion field structure;

[0019] Post-processing analysis module, used for post-processing of combustion field information in the numerical simulation of pintle injection engines;

[0020] The model building module data is connected to the numerical calculation module, and the numerical calculation module data is connected to the post-processing analysis module.

[0021] The beneficial effects of the present invention are:

[0022] 1. The present invention improves the working continuity and accuracy of the full-process simulation of the pintle injection engine by extracting particle information from the cold jet atomization simulation and indirectly coupling it to the hot combustion simulation.

[0023] 2. The present invention can visualize and quantify the spatial distribution of propellant droplets, combustion temperature and pressure, and various key components under the combustion conditions of a pintle injection engine. Through three-dimensional numerical simulation of variable operating conditions, it can provide intuitive theoretical support for clarifying the combustion mechanism of the pintle injection engine and its optimization and regulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart of a numerical method for a pintle injection engine combustion simulation method and system according to the present invention;

[0025] Figure 2 It is a system diagram of the numerical model of the present invention;

[0026] Figure 3 This is a working principle diagram of the pintle injection engine of the present invention;

[0027] Figure 4 This is a schematic diagram of an engine test for a calculation example of the present invention;

[0028] Figure 5 Schematic diagram of the particle information indirect coupling method of the present invention;

[0029] Figure 6 A computational domain grid diagram of a pintle injection engine according to the present invention;

[0030] Figure 7 This is a diagram showing the spray combustion temperature field information of an example of the numerical model of the present invention;

[0031] Figure 8 Schematic diagram of the computing and storage device of the present invention. DETAILED DESCRIPTION

[0032] The following will provide a clear and complete description of the relevant technologies in the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0033] refer to Figures 1 to 8 As shown, this embodiment provides an indirect coupling method for cold and hot state numerical simulation of a pintle injection engine, comprising the following steps:

[0034] Step 1: Establish the computational domain of the pintle injection engine and divide the grid;

[0035] Step 2: Perform a cold-state jet atomization numerical simulation on the pintle injection engine and collect statistics on the particle information of the atomized droplets;

[0036] Step 3: The particle information collected in the cold state numerical simulation is used as input to couple to the hot state combustion numerical simulation.

[0037] Step 4: Export the combustion numerical simulation results of the pintle injection engine and perform post-processing analysis.

[0038] In the numerical simulation of this invention, the computational domain is established based on the fluid space contained within the inner wall of a specific pintle injection engine. The computational domain should cover the entire region of the propellant jet atomization and combustion flow processes. The computational domain should be selected to ensure information integrity while improving computational efficiency.

[0039] In Step 2 of the present invention, a volume of fluid method (VoF)-Large Eddy Simulation (LES) calculation is performed on the example pintle jet atomization flow. This involves setting inlet flow boundary conditions based on the engine example and iteratively calculating various numerical values using the PIMPLE method. The calculation results are extracted and analyzed to calculate the velocity, particle size, mass, and spatial distribution of the droplet particles.

[0040] In Step 3 of the present invention, the eddy dissipation conceptual model is coupled with a simplified multi-step reaction mechanism of 42 reactions and 27 components to carry out the numerical simulation of the pintle injection engine combustion. The design operating conditions are calculated based on the particle data as the propellant input parameters.

[0041] In Step 4 of the present invention, the above calculation results are post-processed to obtain a series of data results, including but not limited to spatial distribution information of the pintle injection engine such as temperature, pressure, velocity, key reaction components, droplets, etc.

[0042] refer to Figure 2 The present invention constructs a pintle injection engine numerical simulation system, comprising:

[0043] The model building module is used to establish the computational domain of the pintle injection engine and construct a numerical model for indirect coupling between cold and hot states;

[0044] Numerical calculation module, used for numerical calculation of pintle injection engine simulation, including particle information of cold jet atomization and hot combustion field structure;

[0045] The post-processing analysis module is used to post-process the combustion field information in the numerical simulation of the pintle injection engine.

[0046] refer to Figure 3 and Figure 4The working process studied in this invention is as follows: two propellants are injected into the combustion chamber through the axial and radial inlets of the pintle injector, where they collide, fragment, atomize, evaporate, and mix. They then burn in the combustion chamber, forming high-temperature, high-pressure combustion gases that are then ejected through the tail nozzle. In the experimental example, the test results were measured using a pressure sensor on the engine dome and an infrared temperature measurement device above the throat wall.

[0047] refer to Figure 8 The present invention provides a computing and storage device, including a processor, an operating system, a memory and a computing program, which can implement the above numerical simulation system steps and save all information of the entire computing process.

[0048] The numerical simulation examples of the present invention are as follows:

[0049] Example operation steps based on Figure 1 It is divided into 4 steps:

[0050] The first step is to establish the computational domain and divide the grid based on the example engine, refer to Figure 6 , Figure 6 (a) is the numerical simulation grid of jet atomization, Figure 6 (b) is the combustion numerical simulation grid;

[0051] The second step is to set the inlet boundary conditions according to the example. The radial propellant mass flow rate is 3.249 kg / s and the axial propellant mass flow rate is 1.97 kg / s. The atomized particle information in the statistical calculation results is coupled to the discrete particle model. Figure 5 ;

[0052] In the third step, the Euler-Lagrangian method is used to couple the discrete particle input with the continuous phase ambient gas. The combustion behavior of the propellant is calculated through the Chemkin solver under the simplified multi-step reaction mechanism of 42 reactions and 27 components combined with the eddy dissipation conceptual model. The mixed boundary is used to comprehensively consider the effects of heat convection, heat conduction and heat radiation on the wall temperature, and the steady-state operation performance parameters of the engine are obtained by using the unsteady-state droplet coupling steady-state calculation method.

[0053] The fourth step is to analyze the numerical simulation results by setting monitoring points and cloud slices. The numerical simulation and test results in the example refer to Table 1, and the results of the combustion chamber temperature, streamlines, and droplet distribution refer to Figure 7 .

[0054] Table 1

[0055] parameter Simulation results Test results Room pressure / MPa 1.933 1.968 Throat outer wall temperature / K 1505 1573

[0056] This implementation improves the problem that most existing numerical combustion methods are not well coupled with cold-state results. A numerical simulation method and coupling method for the entire operation process of a pintle injection engine are designed. The calculation has good stability and accurate results. The combustion performance of the pintle injection engine under different operating conditions can be calculated by changing the initial conditions, thereby reducing the engine test cost and shortening the research cycle.

[0057] This implementation enhances the connection and coupling between the pintle injector jet atomization and the engine combustion chamber simulation, can intuitively represent the entire working process of the pintle injector engine and its combustion mechanism in three-dimensional form, can perform preliminary configuration optimization and combustion mechanism exploration of the pintle injector engine, and provide an effective means for the forward design of the pintle injector engine.

[0058] In summary, the present invention improves the working continuity and accuracy of the full-process simulation of the pintle injection engine by extracting particle information from the cold jet atomization simulation and indirectly coupling it to the hot combustion simulation. Therefore, the present invention can be applied to the design and development of liquid rocket engines, which can reduce the number of test cycles, save R&D costs and optimize the preliminary selection.

[0059] It should be emphasized that the above are only preferred embodiments of the present invention and do not limit the present invention in any form. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A pintle injection engine combustion simulation method, characterized in that: The following steps are involved: Step 1: Establish the computational domain of the pintle injection engine and divide the grid; Step 2: numerically simulate the cold jet atomization of the pintle injection engine and calculate the particle information of the atomized droplets; Step 3: The particle information collected in the cold state numerical simulation is coupled to the hot state combustion numerical simulation as input conditions; Step 4: Export the combustion numerical simulation results of the pintle injection engine and perform post-processing analysis.

2. The pintle injection engine combustion simulation method according to claim 1, characterized in that: In step 1, the calculation domain is constructed based on the fluid space contained in the inner wall of a specific pintle injection engine, and the calculation domain covers the entire region of the propellant jet atomization and combustion flow process.

3. The pintle injection engine combustion simulation method according to claim 1, characterized in that: The step 2 specifically includes: performing a fluid volume method-large eddy simulation calculation on the example pintle jet injection flow atomization, and the fluid volume method-large eddy simulation calculation includes: setting the inlet flow boundary conditions according to the engine example, using the fluid volume method to calculate the two-phase interface, using large eddy simulation to calculate turbulence development, and using the PIMPLE method to iteratively calculate various numerical values.

4. The pintle injection engine combustion simulation method according to claim 3, characterized in that: In step 2, after iteratively calculating various values using the PIMPLE method, the calculation results are extracted and analyzed to statistically analyze the velocity, particle size, mass, and spatial distribution position information of the droplet particles.

5. The pintle injection engine combustion simulation method according to claim 1, characterized in that: In step 3, a pintle injection engine combustion numerical simulation is carried out by coupling the eddy dissipation conceptual model with the simplified multi-step reaction mechanism of each reaction and each component, and the design operating conditions are calculated based on the particle data as the propellant input parameters.

6. The pintle injection engine combustion simulation method according to claim 1, characterized in that: In step 4, the combustion numerical simulation results include: temperature, pressure, velocity, key reaction components, and droplet spatial distribution of the pintle injection engine.

7. A pintle injection engine combustion simulation system, characterized in that: The combustion simulation system is used to implement the pintle injection engine combustion simulation method according to any one of claims 1 to 6, and the combustion simulation system includes: The model building module is used to establish the computational domain of the pintle injection engine and construct a numerical model for indirect coupling between cold and hot states; Numerical calculation module, used for numerical calculation of pintle injection engine simulation, including particle information of cold jet atomization and hot combustion field structure; Post-processing analysis module, used for post-processing of combustion field information in the numerical simulation of pintle injection engines; The model building module is data-connected to the numerical calculation module, and the numerical calculation module is data-connected to the post-processing analysis module.

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