Research On Diaphragm Rupturing And Gas Flow Rule Of Diaphragm-based Light-gas Gun

Light gas gun is a hypervelocity launching technique which is feasible and widely used.The isolation diaphragm,as a sealing element between the gas chambers,is vital to the work of the light gas gun.When the light gas gun starts,the process of rupturing diaphragm has some influence on the launching performance.However,the study on this process is often neglected in the traditional research on light gas gun.In this paper,it is divided into process of failure and process of deployment.Process of failure is a large deformation and high strain rate process,which involves the failure of materials.The interaction between the diaphragm and the highpressure light gas exists in the process of deployment.In this paper,based on the background of diaphragm-based light gas gun,the dynamic simulation of diaphragm failure process is carried out with finite element method,and the dynamic response law of diaphragm and the distribution and variation law of surrounding flow field are analyzed.The main research contents are as follows:(1)In order to simulate the dynamic response of diaphragm failure process,a domain finite element model which only includes solid region is established.According to different critical rupturing pressure,numerical simulation was used to analyze the influence of diaphragm size and material which is selected on the failure process.The results show that the critical rupturing pressure increases almost linearly with the increase of effective thickness,but the change of diaphragm thickness has no significant effect on the critical rupturing pressure.Under the same shooting condition,the rupture time of the diaphragm which selects Al6061-T6 as material is earlier than the diaphragm which selects 304 stainless steel as material.(2)The finite element method is used to establish the fluid-solid coupling model for the diaphragm deployment process of light gas gun,and the combined solution of the structure domain and the fluid domain is carried out.The results show that the maximum velocity region of the flow field mainly concentrates on the central jet in the initial stage.With the deployment of the diaphragm,the jet region expands gradually,and the high-pressure light gas working substance expands continuously to the low-pressure region.The maximum velocity increases and stabilizes gradually during the whole process,the higher the speed is,the lower the temperature is in the region.The maximum stress of the diaphragm is mainly concentrated near the groove root in the deployment process.(3)The speed of diaphragm deployment and the pressure rising speed of low-pressure side are taken as performance evaluation indicators.The effects of rupturing pressure,temperature of gas injection in high-pressure side,gas injection type,the selection diaphragm material and groove shape on the deployment performance were analyzed.The results show that rupturing pressure and temperature of gas injection in high-pressure side have significant effects on the deployment process.When the rupture pressure is 6MPa,the speed of diaphragm deployment is increased by 30.7% compared with 4MPa,and the pressure increase speed of the low-pressure side is increased by 199%.When temperature of gas injection in high-pressure side is 873 K,the speed of diaphragm deployment is 4.8% higher than 273 K,and the low-pressure side pressure increase speed is increased by 19.8%.With the permission of strength,the thinner the diaphragm is,the better the deployment performance of the diaphragm is.It is not obvious for effect on the deployment process of the diaphragm by changing the gas injection type.In low pressure working conditions,Al6061-T6 is suitable for the material of diaphragm.In high pressure working conditions,304 stainless steel should be used as the material of diaphragm.In the diaphragm-based light gas gun,a diaphragm with the shape of six grooves should be used as the isolating diaphragm.This study reproduces the process of failure and deployment,and reveals mechanism about rupturing diaphragm and working of diaphragm-based light-gas gun.The study provides vital reference for optimal design of diaphragm and improvement about performance of interior ballistic.