Two-phase transonic calculation of solid rocket nozzle in condition of particle size grading

In this paper, we calculated two-phase transonic flow in a solid rocket nozzle in conditions of particle size grading. The gas-phase governing equations are solved by the implicit approximate factorization scheme. The particle-phase governing equations are solved by characteristic scheme. Then both are fully coupled. Finally, the parameter distributions of the transonic flow field of an axisymmetric nozzle are obtained for a solid rocket motor containing any particle mass fraction and different particle sizes. We also discussed the influence of different particle radii and mass fractions on flow fields, and compared the flow field parameters possessing a simple particle size with one possessing particle size grading. At present, an explicit time-dependent method is used in the field calculation of two-phase nozzle generally in our paper. The solution form of the gas-phase equations is implicit time-dependent, the CFL number may be taken to be 6. Convergent rate is quick. The iteration convergence rate of the two-phase calculation depends on the gas-phase calculation. Consequently, computer time is greatly saved. Especially, it will be more advantageous for the coupling of particle size grading. Generally, two-phase field calculation consumes more computer time. Hence its application scope is limited. Especially, it is more difficult to apply when repeatedly using it in optimization design of a motor. Consequently, it is of great practical engineering value to find a two-phase field calculation method reducing greatly computer time.