Performance simulation of a dual thrust rocket motor

The dual thrust rocket motor contains two propellants, booster and sustainer. Booster propellant is a wagon-wheel case-bonded propellant and sustainer propellant is a cartridge loaded propellant with three embedded metal (silver) wires. Booster propellant bums radially and sustainer propellant bums conically. Silver wires with high thermal conductivity conduct heat from combustion gases to the propellant adjacent to silver wire, thus the temperature and burning rate of propellant adjacent to silver wire are highly increased. In this simulation governing equations and boundary conditions were determined in three phases and these equation were solved numerically. In these calculations temperature distributions in metal wire (axially) and in propellant (radially) were determined. By integral method using radial temperature distribution, an average temperature is calculated for propellant adjacent to silver wire. the relation between burning rate and temperature up to autoignition temperature was obtained assuming infinite burning rate at autoignition temperature and by the Crawford bomb information. In internal ballistic calculations, according to the principle of conservation of mass a differential equation for pressure is derived and by its solution pressure and thrust versus frame are determined. The results of pressure and thrust calculations were compared with static test results and both were in good agreement.