Numerical simulation of nozzle damping characteristics in solid rocket motor

For the purpose of investigating the key factors affecting the nozzle damping characteristics of solid rocket motor, numerical simulation of nozzle damping characteristics were carried out to study the influence of the nozzle throat area-to-grain port area ratio and the chamber length, based on the simplified two-dimensional model of the typical columnar grain of solid rocket motor and with use of pulse attenuation method. It was found that the numerical simulation results and empirical formulas theoretical estimate values were in good agreement, confirm the validity of the numerical methods; the study further explored what the empirical formula cannot deal with well, such as the change rules of nozzle convergent half-angle and nozzle convergent surface. The results show that the nozzle convergent half angle plays a vital role in nozzle damping constant. Small convergent half angle is beneficial to the nozzle damping; the convex nozzle provides more damping than the conical nozzle, which in turn provides more damping than the concave nozzle.