Analysis of nonlinear pressure coupled response function of solid propellant

In order to obtain the characteristics of the pressure-coupled response function which was influenced by the multi-order modes acoustic frequency oscillation, the nonlinear combustion instability characteristics of the multi-order mode oscillation in the solid rocket motor were considered, and based on the Quasi-Steady, Homogenous, One-Dimensional (QSHOD) model, the second-order (2nd) mode acoustic of the nonlinear pressure-coupled response model was developed. The model was analyzed and verified by experiments. The results of model show that, the oscillation amplitude of the first-order (1st) mode frequency has a great influence on the pressure-coupled response function, and with the amplitude increase, the pressure coupled response function was changed from the linear to the nonlinear, the peak value of response function changed from single-modal to bi-modal, and the nonlinear response function peak value was formed in the high frequency region. During the 1st mode frequency oscillation, the 2nd mode frequency makes the response function more nonlinear significantly, and has a great influence on the peak value of nonlinear pressure coupled response function. The results of the model were basically the same as the experimental results of typical T-burner.