Convective Heat Transfer in the Pre-Nozzle Volume of a Solid Rocket Motor with a Recessed Nozzle

Consideration is given to the matters of mathematical simulation of heat transfer processes in the pre-nozzle volume of a solid rocket motor with a charge with a star-shaped cross section and a recessed vectorable nozzle. Mathematical simulation methods are used to solve a quasistationary spatial conjugate heat transfer problem. A comparison of the numerical simulation results with the existing experimental data has shown the correctness of the proposed models, schemes, and algorithms. Investigations have been made into the topological features of the structure of a viscous compressible heat-conducting gas near the input surface of a recessed nozzle and into their effects of convective heat transfer in the pre-nozzle volume of a solid rocket motor. For the considered configuration of a solid rocket motor, criterion equations have been proposed for estimating the dimensionless heat transfer coefficient in the recessed nozzle region. The conducted verification of the obtained dependences using the existing experimental data confirms the correctness of the proposed criterion equations. It has been established and shown that the use of the well-known extended empirical Eckert and Kraussold dependences does not allow a correct estimate of the value of heat fluxes in the vicinity of the impermeable surfaces of the engine combustion chamber. Based on the calculation results, criterion equations have been proposed for calculating the Nusselt number in special points on the input surface of the end face of the charge.