Modeling enhanced gas generation rates in a 155 mm ETC gun

The Defence Evaluation and Research Agency (DERA) is investigating a number of different electrothermal-chemical (ETC) gun concepts which utilize solid propellants. One of these concepts uses a capillary plasma generator (CPG). In the CPG concept, electrical energy (EE) is discharged into a polyethylene tube, open at one end only, through two electrodes which are located at each end of the capillary. Plasma vents from the open end of the capillary into a combustion chamber which contains a charge of solid propellant. This paper describes some modeling of 155 mm ETC gun firings that used the CPG concept. In these firings the EE was used either to ignite the charge or to augment the combustion process at pressures up to about 80 MPa. In order to simulate successfully these gun firings, it was necessary to assume that enhanced burning, due to the plasma, of the solid propellant occurred. This paper describes the modeling that was conducted for the 155 mm ETC gun firings and compares the simulations with measured results. The simulations were conducted using one-dimensional (1D) and two dimensional (2D) internal ballistics codes and investigate the zone of influence of the plasma.