The Accurate Prediction Model on the Descent Segment of Solid Rocket Motor Interior Ballistic

After the combustion of the solid rocket motor's grain is basically completed, residual gases continue to be expelled due to remaining grain burning and ablation of the insulation layer in the descent segment of the internal ballistic, generating additional thrust. The paper takes the moment when the combustion of the grain is essentially complete as the starting point of the descent segment, and employs solid modeling to calculate the residual grain burning surface during descent and considering the insulation layer ablation mechanism, combining theoretical mathematical models of motor operation with semi-empirical formulas derived from experiments, presenting an engineering algorithm for the descent segment. The validation of the engineering algorithm was conducted through firing test of ablative motor. The results indicated that the engineering algorithm had a maximum relative error of 11.6%. The model can reasonably predict the energy of the descent segment.