Numerical Simulation Study On Fluid-solid Coupling Dynamics Of Rubber Diaphragm Tank

The current development demand for spacecraft liquid rocket engines is high performance,high push ratio,high operational reliability and low production cost.For liquid rocket engines of small spacecraft,propellant tanks are an important part of them.The use of rubber diaphragm tanks instead of metal diaphragm tanks can effectively reduce production costs.However,the use of rubber diaphragms poses a risk of vibration failure of the liquid filled tank.Aiming at the fluid-solid coupling dynamics of a certain type of spacecraft rubber diaphragm tank,this paper established a finite element model based on its actual structure,and studied the fluid-solid coupling dynamics of the rubber diaphragm tank.The main work and innovations of this paper are as follows:1.Aiming at the actual structure of the rubber diaphragm tank,the finite element model was established.The working principle of the rubber diaphragm tank was expounded.According to the function of each component of the tank,fine finite element models were established for the research key components,simplified finite element models were established for the auxiliary components,and the finite element models were assembled and constrainted.2.Basic mechanics experiments were carried out on rubber materials to determine their material parameters.For the small strain problem of rubber materials,the elastic modulus of rubber materials was measured.For the large strain problem of rubber materials,basic mechanics tests such as uniaxial tensile test and plane tensile test were designed and implemented,and the material model was fitted through test data.Comparing the model with the experimental data proves the correctness of the model.3.The acoustic-solid coupling method was used to simulate the fluid-solid coupling vibration modes of rubber diaphragm tank,and the influence of relevant factors on the coupled modes was obtained.The basic principle of the acoustic-solid coupling method was briefly introduced.And the relevant vibration experiments were simulated by the method.The simulation results were compared with the experimental results to verify the correctness of the method.Using this method,the fluid-solid coupling vibration modes of the rubber diaphragm tank were simulated.And the influence of material parameters and other factors on the coupling frequency of the tank was obtained.4.The fluid-solid coupling dynamic response of the rubber diaphragm tank under vibration excitation was simulated by CEL method,and the location of cracking of the rubber diaphragm was analyzed and judged.The core ideas of SPH method and CEL method were briefly introduced.By comparing the simulation results of the two methods,the CEL method was selected as the final simulation method.The fluid-solid coupling dynamic response of the rubber diaphragm tank was simulated by CEL method.The position of the rubber diaphragm that may be cracked was analyzed and compared with the test results.5.The finite element model of the fluid cavity of the rubber diaphragm was established,and the flipping process of the rubber diaphragm was simulated.The basic principle of the fluid cavity was described.The flip of the metal diaphragm was simulated by nonlinear explicit dynamic method.The test results verified the correctness of the simulation method.This method was used to simulate the flipping process of the rubber diaphragm with ribs and the rubber diaphragm without ribs,and the flipping characteristics were studied.This paper systematically studied the fluid-solid coupling dynamics of rubber diaphragm tanks.The research results can provide technical support for the design,analysis and optimization of rubber diaphragm tanks,and can provide technical reference for solving similar fluid-solid coupling problems.It has important engineering significance.