M. Andisheh Tadbir - Graduate student, Department of Mechanical Engineering, Shiraz University, Shiraz, Iran
M.H. Akbari - Assistant professor & corresponding author, Department of Mechanical Engineering, Shiraz University, Shiraz, Iran

In this work, solid fuel grain combustion and retreat for a rocket system is simulated and the motor thrust is estimated as a function of time. In order to achieve this goal, fundamental relations for solid fuel combustion are implemented. The burning surface area controls the chamber pressure, which in turn governs both the burning rate and thrust. A basic relation between these controlling parameters is used to simulate grain combustion and retreat. Given the burning surface area, the burning rate is estimated at each time step. The estimated burning rate is used to calculate the thrust, and the grain retreat during the time step is also obtained through geometric manipulations. In order to obtain a realistic estimate of the grain retreat during each time step, a commercial design software is utilized. The estimated thrust profile is compared with available experimental data for a particular case, and acceptable agreement is obtained. The procedure developed can be used for the preliminary design of a solid propellant rocket motor.

Grain geometry, grain retreat, burning rate, thrust