The Theoretical And Experimental Research On The Enhanced Burning Of The Electrothermal-chemical Gun

In this dissertation,a research has been made on the enhanced burning effect by the plasma,based on the closed bomb experiments and ETC launch experiments.Amulti-dimensional multiphase interior ballistic model has been built.Depending on the simulation of the interior ballistic model,the parameters in the chamber during the ETC launch process are analyzed.The experimental and theoretical researchs are as follows:A transient time-varying model(TTVM)of the DRPG is built.The influence of the gas flowing back into the DRPG is considered in the TTVM.The mean square errors(MSE)between the simulated and measured current and resistance are calculated,and the accuracy of the TTVM is proved.Depending on the TTVM,the temperature,velocity,density and pressure of the plasma during the discharge process of the DRPG can be simulated.According to the simulated plasma parameters,the velocity of the plasma after the wire exploding is positive,the plasma flows into the chamber and the solid propellants are ignited.With the increasing of the gas pressure in the chamber,the phenomenon of flowing-back gas appears.Because of the mixing of the flowing-back gas and the plasma,the temperature of the plasma decreases,the density of the plasma and the resistance of the DRPG increase.A transient burning rate law including the influence of the rate of the pressure change(dp/dt)is built to improve the Woodley's modified burning rate law.Closed bomb experiments with the 4/7 high-nitrogen solid propellant are performed to study the enhanced gas generation with the plasma.Experiments with the conventional ignition and the capillary plasma generator(CPG)are conducted in the closed bomb.In the experiments with the CPG,the input electric power and the distance between the CPG and the solid propellant are changed.The enhanced burning effect by plasma is studied by analyzing the changing rate of the pressure in the chamber.When the distance between the CPG and the propellant is not changed,the changing rate of the pressure is proportional to the electric power during the electrical discharge.The changing rate of the pressure with the CPG is much higher than that with the conventional ignition post electrical discharge.The enhanced gas generation rate phenomenon of the 4/7 high-nitrogen solid propellant exists during and post electrical discharge.The changing rate of the pressure and the enhanced burning effect by plasma can be improved by reducing the distance between the CPG and the solid propellant or increasing the electric power.A propellant burning model in the closed bomb is established to simulate the closed bomb experiments.In the model,the Woodley's modified burning rate law or the transient burning rate law is used to simulate the burning rate of the propellant.The EGGR coefficient of the 4/7 high-nitrogen solid propellant is equal to 0.005MW-1.Based on the MSE of the pressure,the accuracy of the simulation results of the transient burning rate law is higher than those of the Woodley's modified burning rate law.They are less affected by the changes of the electric power and the distance between the CPG and the propellant.The enhanced gas generation with the plasma in the 30mm ETC launch is studied by experiments and simulations.The DRPG is used in the 30mm ETC launch experiments,and the relationship among electric parameters of the DRPG,interior ballistic parameters and the initial parameters,such as the discharge parameters and the loading charge,is researched through the change of initial parameters.In the condition of synchronous discharging,the peak pressure and the projectile muzzle velocity increase with the electric energy of the DRPG The sequence discharge modules are added to increase the projectile muzzle velocity and control the peak pressure.The influence of the loading charge on the working process of the DRPG can be ignored.Compared with the CPC the stability of the DRPG is reduced,because of the influence of the gas and propellant in the chamber.As the loading charge increasing,the peak pressure increases rapidly,while the increasing effect of the projectile muzzle velocity is reduced.The influence of the interference of electromagnetic field is ignored in the analysis of the changing rate of the pressure.There are two spikes during the increasing of the pressure.The first spike of the changing rate of the pressure increases with the electric power.And the second spike is influenced by the burning process of the propellant.At the same discharge parameters,the second spike increases with the increasing of the loading charge.A lumped parameter model of the ETC launch is established to simulate the ETC launch experiments.In the model,the Woodley's modified burning rate law or the transient burning rate law is used to simulate the burning rate of the propellant.Based on the MSE of the pressure and the error of the projectile muzzle velocity,the simulation results of the transient burning rate law are more suitable to the burning process of the propellant with the plasma than those of the Woodley's modified burning rate law.Depending on the interior ballistics model of the ETC launch,an axisymmetric two-dimensional interior ballistics program of the solid propellant ETC gun(2D-IB-SPETCG)is presented to describe the process of the ETC launch with the CPG and DRPG.The simulation results accord well with the experimental results.The feasibility of the program is proved.The ignition process with the CPG or the DRPG is simulated by the 2D-IB-SPETCG The influence of the PG on the interior ballistics parameters is analyzed.Depending on simulation results,the electric energy ratio and discharge timing sequences are used to analyze the influence of electric parameters(input electric power,discharging timing sequence)and charging parameters(loading density,propellant web thickness)on the pressure wave.In order to control the peak value of the pressure wave,the allowed input electric energy ratio at different discharge timing sequences is calculated.In the condition of synchronous discharging,the allowed input electric energy ratio is less than 0.042 with the CPG In the condition of timing sequence discharging,the allowed input electric energy ratio is proportional to the current pulse duration.The first negative wave value is proportional to the electric energy ratio and inversely proportional to the current pulse duration.In the condition of synchronous discharging,the allowed input electric energy ratio is less than 0.11 with the DRPG The influence of the electric energy ratio on the first negative wave value can be ignored.In the condition of timing sequence discharging,the allowed input electric energy ratio is proportional to the current pulse duration.The first negative wave value is inversely proportional to the electric energy ratio.The influence of changing the propellant web thickness in 30mm ETC launch can be ignored.The interior ballistics process of the ETC launch is studied by experiments and numerical simulations.Experimental and theorical basis for the enhanced burning effect by plasma is provided.The research results are signification to the design and optimization of the ETC gun.