Abstract: In order to study the internal flow field characteristics of ladder-shaped multiple charge rocket motor,the full 3-D internal flow field models for erosion ratio and average erosion ratio were numerically simulated using Fluent software. The secondary development was carried out through User Defined Function(UDF) interface programming. The coordinates and pressure of each node of erosion ratio model and the average pressure of each burning surface of average erosion ratio model are extracted, and the formulas of burning rate and mass flow rate are introduced to control the moving velocity of boundary grid and the mass flow rate of gas inlet per unit area. The spatial distribution information of pressures at each moment in two inner flow field models and the pressure-time curves of three monitoring points in the front, middle and rear of combustion chamber were obtained through numerical simulation. The calculated results of the two models are compared.The inner flow field and the pressure difference between the inside and outside of grain in the erosion ratio model are analyzed. The results show that the maximum pressure difference between the two models is no more than 3%, which is basically the same after the equilibrium pressure section. There is no obvious erosive burning trumpet type in the erosion ratio model during the working process of motor. The maximum pressure difference between the inside and outside of grain in the front high pressure area is not more than 3.9%, and is not more than 8%in the rear low pressure area. The pressure-time curves of the monitoring points is in good agreement with the test data.

Key words: solidrocketmotor, ladder-shapedmultiplecharge, erosiveburning, 3-Dinnerflowfield