Research On The Modeling And Flow Field Characteristics Of Electrothermal Plasma Driven Capillary Discharge

In electrothermal launch technology,electrothermal plasma driven capillary discharge is a key physical process and has always been one of the focuses in the research field of electrothermal launch technology.The process of capillary discharge is very complex which generate strong electromagnetic interference.It is difficult to measure the physical properties of capillary discharge effectively with current measurment technique.Therefore,numerical simulation technique become an important approach in the research of capillary discharge.Present thesis is focused on the development of a high-precision,high-efficiency numerical simulation program for both conventional capillary discharge and the capillary discharge with an extended tube.Depth study is conducted on the flow field characteristics of capillary discharge by using the program.Firstly,based on the analysis of the physical processes of capillary discharge,a onedimensional time-dependent mathematical model for the conventional capillary discharge is established.For the solution of the Saha equation in the numerical simulation of capillary discharge,an algorithm is first proposed which transforms the multidimensional problem of solving the Saha equation into a one-dimensional problem about temperature.This Algorithm can greatly reduce the difficult of solving the Saha equation while obtaining any desired accuracy.On this basis,the program for simulating the capillary discharge is developed and the results is verified by comparing with the experimental data.Secondly,by assuming that the plasma is local fully mixed,a one-dimensional time dependent mathematical model for the capillary discharge with an extended tube is established.This model takes into account factors such as the brass extended tube and multispecies plasma.The capillary discharge with a brass extended tube is simulated with this model.The simulation results shows that metal extended tube could cause the increase of flow field pressure inside the capillary through the "plugging" effect,and the response of capillary flow field to the change of input current would be delayed since the transient effect.By comparing with experimental data,it is found that a relatively better agreement of simulated results with the measured data is achieved.At last,the computational efficiency of the capillary discharge numerical simulation program is studied.By analyzing the time consumption the program,it is found that solving the Saha equation is the most time consuming part in the program.In this thesis,two optimization strategies are proposed to improve the computational efficiency: the optimization of the iterative coefficient and setting iterative initial value dynamically.Numerical tests show that the time consumption of the capillary discharge simulation program could be reduced significantly with these two strategies.