热裂解对超临界RP-3流动和耦合传热影响的数值模拟研究

Pyrolysis has significant influence on the flow and heat transfer of hydrocarbon fuel during the regenerative cooling process. In this article, a three-dimensional (3D) model was developed for numerically studying the flow and heat transfer of pyrolytically reacted RP-3 in the square channel under supercritical pressure. The 24-step pyrolytic reaction mechanism consisting of 18 species was incorporated into the numerical model to simulate the pyrolysis process of RP-3. Numerical investigations of the characteristics of flow resistance and heat transfer have been conducted, with various heat fluxes on the bottom-heated-surface from 2.4~3.6MW/m² and the pressures ranging from 4 to 6MPa. Results reveal that the pressure gradient along the channel abruptly increases due to the further fluid acceleration caused by pyrolysis, which could be more evidently observed under 4MPa. It is found that the heat fluxes at the bottom, side and top wall vary in different ways. Pyrolysis could bring about greater heat transfer enhancement near the bottom wall, and accordingly, the heat flux increase at the bottom interface is about 0.5MW/m². The dual effects of heat absorption and enhanced heat transfer caused by pyrolysis lower the wall temperature with the decrease up to 150K.