Effect of pressure on regenerative cooling process of endothermic hydrocarbon fuel at severe pyrolysis conditions

Regenerative cooling technology with supercritical aviation kerosene as coolant is the optimal thermal management method for advanced aero engines. In order to fill the gap in existing research on the pressure effects at severe pyrolysis, the influence of pressure on the flow field, pyrolysis behaviours, heat transfer, and surface coking are numerically investigated in this study. The results indicate that the velocity-temperature curves at different pressures have two intersections due to the difference in initial pyrolysis temperature, reaction rate, and product distribution. Fuel pyrolysis more easily occurs at high pressure, and elevating pressure improves the fuel heat sink. Besides, a special deterioration of heat transfer is found at high conversion rates because of the combined contribution of weakened primary endothermic reaction and enhanced secondary exothermic reaction. Heat transfer deterioration is delayed at 3.5 MPa due to the high initial pyrolysis temperature and significant flow acceleration. The primary pyrolysis reaction provides more than 80% chemical heat sink and 60% flow acceleration at fully cracked conditions at 5.0 MPa. In addition, inhibiting catalytic coking is the principal method to reduce carbon deposition, and more attention should be paid to carbon deposition under high pressure. The results obtained in this study are expected to provide insights into the selection of operating pressures for advanced aero engines.