Experimental investigation of the pressure-coupled responses of composite propellant with different ammonium perchlorate particles size

In the past few years, some full-scale tactical motors with aluminized composite propellants have suffered strong combustion instability. In order to understand this kind of combustion instability, the combustion response of propellants with different AP particle size was investigated by T-burner. In the present study, based on the T-burner, the pulser and adopted Double-Pulsing test method have been developed for comparing the pressure-coupled response of the aluminized composite propellant A and B. According to the acoustics model of the tactical motor, the test frequencies are set at 250Hz and 140Hz, respectively. The operating pressures of six experiments are 6-7MPa, and different decay constants (alphas 1 and alphas2) and grow constants (combustion alphas) about the two kinds of propellants are obtained. The result shows that the different size distributions of the AP particles in the propellant make the pressure-coupled response of the two samples divergent. The propellants with more fine AP particles are more likely to induce combustion instability, and cause the solid rocket motor more unstable. The results of experiments in the T-burner have a match with the full-scale motors' typical characteristics well. Consequently the high levels of fine AP particles should be used with caution.