Numerical Modeling of Solid Rocket's Grain Starting Process in Transient Mode

In this paper, the solid rocket motor’s grain starting process is simulated numerically by solving Navier-Stockes equations in an axisymmetric, transient laminar mode. Explicit maccormack technique is used for solving the equations. Also, to reach the actual state of grain surface burning and to predict its temperature a suitable heat transfer model is used. So that the preheating of the fuel by the flame can be modeled. By solving the conservative equations of mass, momentum, and energy along with related boundary conditions, one can predict the burning time of the first element of the fuel, its place, and the direction of flame propagation. In addition, the time required for the burning of all the surfaces of the fuel and the time in which the motor burning reaches to a steady state condition could be estimated. Results show that a two-dimensional axisymmetric model is suitable for predicting the transient combustion process in solid fuel motors. Also, a motor designer can design the best igniter based on grain type and size. The numerical results are compared with the results of the experimental tests and their accuracy is evaluated.