Numerical study of solid-fuel combustion under supersonic crossflows

The combustion of solid fuels under supersonic crossflows has been studied using a comprehensive numerical analysis. The formulation is based on the time-dependent multidimensional compressible Navier-Stokes equations and species transport equations. Features of this approach include consideration of finite-rate chemical kinetics and variable properties. Turbulence closure is achieved using the Baldwin-Lomax algebraic model. The governing equations are solved numerically using a flux-vector splitting lower-upper symmetric successive overrelaxation technique that treats source terms implicitly. The effects of various operating conditions on the combustion behavior of the hydroxyl-terminated polybutadiene-based solid-fuel samples are treated in detail. Results indicate that both inlet temperature and pressure have strong influences on the burning rate of the fuel sample. For the operating range considered, an optimum pressure is required to maximize the burning rate. The sample burns increasingly faster with pressure from 1 to 4 atm. However, at a higher pressure, the energy released by combustion is not sufficient to further raise the temperature of the crossflow. This results in a decrease in heat feedback to the fuel sample, consequently causing a slight reversal of the burning rate trend with pressure.