Thermal structure evaluation and optimization model construction method suitable for composite material spray pipe

Abstract

The invention discloses a thermal structure evaluation and optimization model construction method suitable for a composite material spray pipe, and the method comprises the steps: constructing a multi-field coupling analysis model through building a geometric model and application conditions of the spray pipe, and respectively building models for a flow problem, a heat transfer problem and a structure problem, and solving the models; flow field-heat transfer coupling is obtained by inputting a flow result into a thermal load boundary condition for heat transfer calculation; and heat transfer-mechanical coupling is obtained by inputting a heat transfer result into a boundary condition of mechanical analysis, and a thermal evaluation model for flow-heat transfer-mechanical nonlinear coupling analysis is completed. And an optimization model of the composite material spray pipe is obtained by correcting the initial seam size and adopting a multi-field coupling analysis method. According to the method, a real temperature field and a structural stress field of the spray pipe under high-temperature and high-pressure working conditions can be disclosed, the influence of the spray pipe seam on the thermal structure can be disclosed, and the practical engineering problem of thermal structure integrity prediction and optimization evaluation under the working state of the composite material spray pipe is solved.

Description

Technical Field

[0001] The invention belongs to the field of rocket technology, and in particular relates to a thermal structure evaluation and optimization model building method suitable for a composite material nozzle. Background Art

[0002] Large-sized solid rocket engines are important power units for long-range guided rockets. As solid rocket engines develop towards ultra-high temperatures (above 4000K) and ultra-high pressures (10MPa), the working environment of the nozzle, as a key component for maintaining stable pressure-energy conversion, is becoming increasingly harsh. Composite nozzles have the characteristics of low passive mass and good ablation resistance, and are widely used in large-sized solid rocket engines. When evaluating the thermal structural integrity of composite nozzles of solid rocket engines, traditional methods usually use analogies with mature models and empirical coefficients. It is difficult to simulate and evaluate the thermal structural integrity of the nozzle under working conditions before hot testing, and there is a lack of simulation and analysis methods for the coupling of multiple physical fields such as flow, heat transfer, and structure. It is necessary to study a method that can quickly and conveniently predict the thermal structural integrity of the nozzle, understand the physical field state of the composite nozzle under working conditions, and thus reasonably predict the thermal and stress behaviors in the nozzle, and improve the evaluation and optimization methods of the thermal structural integrity of the nozzle. Summary of the invention

[0003] In order to overcome the deficiencies of the prior art, the present invention provides a method for building a thermal structure evaluation and optimization model suitable for composite nozzles. By establishing a geometric model and application conditions of the nozzle, a multi-field coupling analysis model is constructed, and models are established and solved for flow problems, heat transfer problems, and structural problems respectively; by inputting the flow results into the thermal load boundary conditions of the heat transfer calculation, the flow field-heat transfer coupling is obtained; by inputting the heat transfer results into the boundary conditions of the mechanical analysis, the heat transfer-mechanical coupling is obtained, and the thermal evaluation model of the flow-heat transfer-mechanical nonlinear coupling analysis is completed. The optimization model of the composite nozzle is obtained by correcting the initial joint size and the multi-field coupling analysis method. The present invention helps to reveal the real temperature field and structural stress field of the nozzle under high temperature and high pressure working conditions, helps to reveal the influence of the nozzle joint on the thermal structure, and solves the practical engineering problems of thermal structure integrity prediction and optimization evaluation of the composite nozzle under working conditions.

[0004] The technical solution adopted by the present invention to solve the technical problem is as follows:

[0005] Step 1: Establish geometric analysis and analyze the applied boundary conditions;

[0006] Taking the large-size composite nozzle of solid rocket engine as the research object, an axisymmetric geometric model is established;

[0007] Step 2: Establish a multi-field coupling analysis model for the geometric model established in step 1 and the applied boundary conditions;

[0008] Step 2-1: Establish boundary conditions for the flow problem of composite nozzle of large-scale solid rocket motor;

[0009] Step 2-2: Convert the applied boundary conditions into the boundary conditions of the nozzle flow problem;

[0010] Step 2-3: Use the fluent solver to solve the boundary conditions of the nozzle flow problem;

[0011] Step 2-4: Obtain the temperature field and convection heat transfer coefficient at the interface between the nozzle and the airflow;

[0012] Step 3: Establish heat transfer analysis model;

[0013] Step 3-1: Analyze the nozzle thermal environment to obtain heat transfer boundary conditions;

[0014] Step 3-2: Transfer the result of step 3-1 to the thermal load boundary condition of the heat transfer model to update the thermal load of the flow field when the nozzle is working;

[0015] Step 3-3: Solve the temperature field of the nozzle at different working times through the unsteady heat transfer module of ANSYS Workbench;

[0016] Step 3-4: Obtain updated joint values ​​through the contact surface temperature field results and the thermal expansion coefficients of the throat lining material and the diffuser material, correct the contact state between the nozzle convergent section and the diffuser section, and input the results into the structural mechanics analysis model through the APDL programming language;

[0017] Step 4: Establish a structural mechanics analysis model;

[0018] Step 4-1: Obtain mechanical boundary conditions from the nozzle force analysis and set the interface between the nozzle and the combustion chamber as the boundary condition for axial displacement.

[0019] Step 4-2: Solve the stress field of the nozzle at different working times through the unsteady mechanical analysis module of ANSYS Workbench;

[0020] Step 4-3: Obtain the analysis results of the nozzle stress field, determine the contact state of the nozzle convergent section and the diffuser section according to the initial joint size, correct the thermal load boundary conditions in the heat transfer problem by calculating the contact thermal resistance, and solve to obtain a new heat transfer field;

[0021] Step 5: Complete the visualization result output;

[0022] The temperature field and stress field of the output nozzle at different working moments, as well as the contact state and stress field of the nozzle throat lining, convergent section, and diffuser section;

[0023] Step 6: Determine whether the stress state of the throat liner, convergent section, and diffuser section is less than the allowable stress of the material, and change the nozzle joint value according to the thermal structure analysis results of the composite nozzle to find the optimal nozzle joint value;

[0024] Step 6-1: If the stress of the nozzle throat lining, convergent section, and diffuser section does not meet the allowable stress requirements, change the initial nozzle joint size to obtain the optimized nozzle model;

[0025] Step 6-2: For the optimized nozzle model, according to steps 2 to 4, a nozzle multi-field coupling analysis model is established and visualization results are obtained;

[0026] Step 6-3: If the stresses of the nozzle throat lining, convergent section, and diffuser section meet the allowable stress requirements of the material, the optimization is terminated and the optimal joint design value of the nozzle is obtained.

[0027] Preferably, the structural parameters of the composite nozzle of the solid rocket engine are: throat diameter φ128mm, outlet diameter 1050mm.

[0028] The beneficial effects of the present invention are as follows:

[0029] 1. The present invention helps to reveal the real temperature field and structural stress field of the nozzle under high temperature and high pressure working conditions, helps to reveal the influence of the nozzle joint on the thermal structure, provides a theoretical basis for nozzle design, and solves the practical engineering problems of thermal structure integrity prediction and optimization evaluation under the working state of composite nozzles.

[0030] 2. The present invention can accurately simulate and analyze the thermal structure state of the composite nozzle during operation, provide a theoretical basis for nozzle design optimization, and solve the problem of fire failure caused by gap control in the composite nozzle of a large-size composite engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A flow chart of the method of the present invention;

[0032] Figure 2 A schematic diagram of mesh division details in an embodiment of the present invention;

[0033] Figure 3 A schematic diagram of the seam arrangement in an embodiment of the present invention;

[0034] Figure 4 The simulation results of the nozzle coupled temperature field in the embodiment of the present invention;

[0035] Figure 5 Numerical simulation results of the throat liner stress field in the embodiment of the present invention;

[0036] Figure 6 Numerical simulation results of throat liner deformation in an embodiment of the present invention;

[0037] Figure 7 Numerical simulation results of the diffusion section deformation in the embodiment of the present invention. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0039] The technical problem to be solved by the present invention is: considering the influence of nozzle joints on temperature field and stress field, accurately simulating and analyzing the thermal structural integrity of the composite nozzle, taking the joint value as the independent variable and the nozzle stress field as the dependent variable, and obtaining the composite nozzle thermal structure evaluation and optimization model. It is helpful to reveal the real temperature field and structural stress field of the nozzle under high temperature and high pressure working conditions, and to reveal the influence of nozzle joints on thermal structure, providing a theoretical basis for nozzle design, and solving the practical engineering problems of thermal structural integrity prediction and optimization evaluation of composite nozzles under working conditions.

[0040] The present invention establishes a composite nozzle thermal structure evaluation and optimization model. By establishing the geometric model and application conditions of the nozzle, a multi-field coupling analysis model is established, and the flow problem, heat transfer problem and structural problem are modeled and solved respectively. By inputting the flow results into the thermal load boundary conditions of the heat transfer calculation, the flow field-heat transfer coupling is obtained; by inputting the heat transfer results into the boundary conditions of the mechanical analysis, the heat transfer-mechanical coupling is obtained, and the initial joint size is corrected by the mechanical deformation results. After contact judgment and contact thermal resistance correction, an updated thermal load result is obtained to complete the thermal evaluation model of flow-heat transfer-mechanical nonlinear coupling analysis. The optimization model of the composite nozzle is obtained by correcting the initial joint size and the multi-field coupling analysis method. The calculation results are visualized and post-processed, and the thermal structure state of the composite nozzle when working is accurately simulated and analyzed, providing a theoretical basis for nozzle design optimization, and solving the problem of fire failure caused by gap control in the composite nozzle of a large-size composite engine.

[0041] Example:

[0042] like Figure 1 As shown, the main structural parameters of the nozzle of a solid rocket engine are: throat diameter φ128mm, outlet diameter 1050mm. According to the above nozzle parameters, the nozzle thermal structure evaluation and optimization method of the present invention is used and combined with the accompanying drawings to carry out simulation calculation.

[0043] Step 1: Establish geometric analysis and apply boundary conditions for analysis.

[0044] The large-scale composite nozzle of solid rocket engine is taken as the research object, and an axisymmetric geometric model is established.

[0045] Step 2: Establish a multi-field coupling analysis model based on the geometric model and application conditions established in step 1.

[0046] Step 2.1 Establish boundary conditions for the large-scale solid rocket engine composite nozzle flow problem established in step 1.

[0047] Step 2.2 converts the application conditions in step 1 into boundary conditions for the nozzle flow problem.

[0048] Step 2.3 Use the fluent solver to solve the nozzle flow boundary conditions in step 2.2. Pay attention to the nozzle calculation domain mesh pre-processing and boundary condition settings. Figure 2 shown.

[0049] Step 2.4 analyzes the flow results in step 2.2 to obtain the temperature field and convection heat transfer coefficient at the interface between the nozzle and the airflow.

[0050] Step 3: Establish a heat transfer analysis model.

[0051] Step 3.1 Analyze the nozzle thermal environment to obtain the heat transfer boundary conditions. Pay attention to the influence of natural convection of the outside air and the setting of the air convection coefficient.

[0052] Step 3.2: Transfer the flow field analysis results to the heat load boundary conditions of the heat transfer model and update the heat load of the flow field when the nozzle is working. Note the data transfer of the nozzle working wall temperature field and the corresponding convective heat transfer coefficient.

[0053] Step 3.3: Use the unsteady heat transfer module of ANSYS Workbench to solve the temperature field of the nozzle at different working times.

[0054] Step 3.4 obtains the updated joint value through the contact surface temperature field results and the thermal expansion coefficients of the throat lining material and the diffusion section material, corrects the contact state between the nozzle convergence section and the diffusion section, and inputs the results into the structural mechanics analysis model through the APDL programming language. Figure 3 shown.

[0055] Step 4: Establish a structural mechanics analysis model.

[0056] Step 4.1 Obtain mechanical boundary conditions for nozzle force analysis. Set the nozzle and combustion chamber interface position as the boundary condition of axial displacement.

[0057] Step 4.2 solves the stress field of the nozzle at different working times through the non-steady-state mechanical analysis module of ANSYS Workbench.

[0058] Step 4.3 obtains the analysis results of the nozzle stress field, determines the contact state of the nozzle convergence section and the diffusion section according to the initial joint size, modifies the thermal load boundary conditions in the heat transfer problem by calculating the contact thermal resistance, and obtains the new heat transfer field by solving.

[0059] Step 5: Complete the output of visualization results. Output the temperature field and stress field of the nozzle at different working times, as well as the contact state and stress field of the nozzle throat lining, convergent section, and diffuser section.

[0060] Step 6: Determine whether the stress state of the throat liner, convergent section, and diffuser section is less than the allowable stress of the material, and change the nozzle joint value according to the thermal structure analysis results of the composite nozzle to find the optimal nozzle joint value.

[0061] Step 6.1 If the stress of the nozzle throat lining, convergent section, and diffuser section does not meet the allowable stress requirements, the initial nozzle joint size needs to be changed to obtain the optimized nozzle model.

[0062] Step 6.2: For the optimized nozzle model, according to steps 2 to 4, a nozzle multi-field coupling analysis model is established and visualization results are obtained.

[0063] Step 6.3 If the stresses of the nozzle throat lining, convergent section, and diffuser section meet the material allowable stress requirements, the optimization is terminated and the optimal joint design value of the nozzle is obtained.

[0064] The numerical results are visualized as follows: Figures 4 to 7 As shown, there are respectively a temperature field numerical simulation cloud map, a stress field numerical simulation cloud map, a deformation field numerical simulation cloud map and a diffusion section deformation field numerical simulation cloud map of the thermal structure evaluation and optimization model of the nozzle multi-field coupling in an embodiment of the present invention.

Claims

1. A method for building a thermal structure evaluation and optimization model for a composite nozzle, characterized in that: The steps include: Step 1: Establish geometric analysis and analyze the applied boundary conditions; Taking the large-size composite nozzle of solid rocket engine as the research object, an axisymmetric geometric model is established; Step 2: Establish a multi-field coupling analysis model for the geometric model established in step 1 and the applied boundary conditions; Step 2-1: Establish boundary conditions for the flow problem of composite nozzle of large-scale solid rocket motor; Step 2-2: Convert the applied boundary conditions into the boundary conditions of the nozzle flow problem; Step 2-3: Use the fluent solver to solve the boundary conditions of the nozzle flow problem; Step 2-4: Obtain the temperature field and convection heat transfer coefficient at the interface between the nozzle and the airflow; Step 3: Establish heat transfer analysis model; Step 3-1: Analyze the nozzle thermal environment to obtain heat transfer boundary conditions; Step 3-2: Transfer the result of step 3-1 to the thermal load boundary condition of the heat transfer model to update the thermal load of the flow field when the nozzle is working; Step 3-3: Solve the temperature field of the nozzle at different working times through the unsteady heat transfer module of ANSYS Workbench; Step 3-4: Obtain updated joint values ​​through the contact surface temperature field results and the thermal expansion coefficients of the throat lining material and the diffuser material, correct the contact state between the nozzle convergent section and the diffuser section, and input the results into the structural mechanics analysis model through the APDL programming language; Step 4: Establish a structural mechanics analysis model; Step 4-1: Obtain mechanical boundary conditions by analyzing the nozzle force, and set the nozzle and combustion chamber interface position as the boundary condition of axial displacement; Step 4-2: Solve the stress field of the nozzle at different working times through the unsteady mechanical analysis module of ANSYS Workbench; Step 4-3: Obtain the analysis results of the nozzle stress field, determine the contact state of the nozzle convergent section and the diffuser section according to the initial joint size, correct the thermal load boundary conditions in the heat transfer problem by calculating the contact thermal resistance, and solve to obtain a new heat transfer field; Step 5: Complete the visualization result output; The temperature field and stress field of the output nozzle at different working moments, as well as the contact state and stress field of the nozzle throat lining, convergent section, and diffuser section; Step 6: Determine whether the stress state of the throat liner, convergent section, and diffuser section is less than the allowable stress of the material, and change the nozzle joint value according to the thermal structure analysis results of the composite nozzle to find the optimal nozzle joint value; Step 6-1: If the stress of the nozzle throat lining, convergent section, and diffuser section does not meet the allowable stress requirements, change the initial nozzle joint size to obtain the optimized nozzle model; Step 6-2: For the optimized nozzle model, according to steps 2 to 4, a nozzle multi-field coupling analysis model is established and visualization results are obtained; Step 6-3: If the stresses of the nozzle throat lining, convergent section, and diffuser section meet the allowable stress requirements of the material, the optimization is terminated and the optimal joint design value of the nozzle is obtained.

2. A method for building a thermal structure assessment and optimization model for a composite nozzle according to claim 1, characterized in that: The structural parameters of the composite nozzle of the solid rocket engine are: throat diameter φ128mm, outlet diameter 1050mm.

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