Numerical analysis on effect of head cavity on resonance damping characteristics in solid rocket motors

In order to reveal the effect of head-end cavity on resonance damping characteristics in solid rocket motors, large-eddy simulations were carried out to study the oscillation flowfield induced by obstacle vortex shedding on the foundation of VKI experimental motor. Pressure oscillation frequencies and amplitudes were obtained, and compared with the experimental data. It is investigated that oscillation amplitudes reduce remarkably after adding a cavity at the head-end. It is proved that Rayleigh criterion is effective for design of resonance damping. The results indicate that cavity volume, location and configuration have great effect on the oscillation amplitude. The substance of altering grain configuration is a comprehensive process of adding and extracting mass. The damping effect is not caused by the complicated flowfield at the head-end. Also, it is neglected if altering grain configuration at the pressure node. It is concluded that large mass flux added at pressure antinode could result in significant amplitude; meanwhile, the damping effect of cavity is stronger if the cavity is nearer to pressure antinode.