Evaluation of Nozzle Damping Characteristics by a Pulsed Method

A pulsed method is numerically provided in this paper to evaluate the nozzle damping characteristics. In linear consideration of solid rocket motor, the pulsed oscillation pressure will be attenuated in an exponentially way by the nozzle damping. Based on this method, the damping constants of three models with nozzle throat radii of R-t=25mm, R-t=30mm and R-t=35mm are numerically studied. The results show that the first axial acoustic combustion instability is easily excited when a pulse is exerted on the chamber. The pulse intensity and mean chamber pressure have no effect on the nozzle damping characteristics. The factor that can greatly influence the damping constant is the nozzle throat radius. The bigger nozzle throat radius, the greater the nozzle damping effect. The calculated results are consistent well with the theoretical values. (c) 2014 Published by Elsevier Ltd.