The effect of mixing and heat transfer on regression rate of TAGN-based fuel in a segregated AP/TAGN solid motor

The effect of mixing and heat transfer on regression rate of TAGN-based fuel of a segregated AP/TAGN solid motor is studied in the present study. A regression rate model of TAGN-based fuel under coupled combustion is developed and validated based on detailed reaction mechanism. The two-dimensional mixing characteristics in boundary layer and the effect on regression rate of TAGN-based fuel are analyzed in detail. The simulation results show that the increase of initial temperature of oxidizer gas leads to better mixing in the axial direction and higher temperature of burning surface. However, the mass concentration of O₂ decreases greatly due to the increasing consumption by primary combustion reactions of AP-derived gaseous species. Therefore, the regression rate of burning surface decreases slightly. With inflow Mach number increasing from 0.32 to 0.75, mixing in the boundary layer is greatly enhanced. Therefore, both the temperature and regression rate increase with inflow Mach number. As pressure increases from 4 MPa to 10 MPa, the primary reactions of AP-derived gas species are also enhanced. Therefore, the mass concentration of O₂ decreases rapidly, which leads to oxygen-lean combustion in the combustion chamber. Therefore, the temperature of burning surface decreases while the regression hardly varies despite of the better mixing near the burning surface at high pressure. The results show that the coupled combustion reactions between inflow oxidizer gas and fuel gas mainly occur in a narrow belt-like region of the boundary layer. The results show that the regression rate of solid fuel in the segregated solid motor is controlled by the competition between primary combustion and coupled combustion.