Experimental and numerical study of combusting solid propellant and axisymmetric flow field with moving boundary

The objective of this paper is to simulate compressible gases produced by combustion of solid propellant inside a cylinder with moving boundary experimentally and numerically. Combusting solid propellant in a closed cylinder is a two-phase process and causes increasing in pressure. In this paper, a one dimensional combustion model is used. Regression velocity of solid propellant (dx/dt) is function of its shape and material. This investigation is based on prediction of burning rate by a function of pressure and piston displacement. Therefore using experimental pressure profile for two cases and obtaining the pressure function and displacement coefficient, it can be applied to all propellant charge weights. When solid propellant is burned completely, flow field can be considered as a compressible gas. Therefore Axisymmetric Euler Equation can be used to simulate this flow field. A finite volume upwind scheme based on the Roe's flux-difference splitting method is employed here. To capture moving boundary fixed grid method is used. Applying (VOF) technique the velocity and displacement of the projectile and piston is achieved. Chamber pressure versus time and exit velocity is determined by ballistic measurement equipment, which is contained a piezo-electric transducer and two light screens. The numerical results compared well with experimental results. (author)