Fluid-thermo-structural response of actively cooled scramjet combustor in hypersonic accelerating-cruise flight

Abstract

This paper presents a three-dimensional transient fluid-thermo-structural study of an actively cooled sandwich panel under hypersonic accelerating-cruise flight conditions. The thermo-structural loads are estimated using a high-speed gas-dynamic flow model combined with Eckert's reference temperature method. The thermal safeguard capacity with endothermic fuel-based active cooling shows design optimization scope compared to the passive system. A passive system has to survive excessively high temperatures with a less severe thermal gradient over the panel thickness and a high heat leakage into the structural interior or back wall. The actively cooled system with fuel develops significant panel bending due to a through-thickness thermal gradient in the cooling channels. For a Mach 7 flight, an actively cooled system reduces the bending deformation by 90% and improves the thermal safeguard capacity by 70% compared to a passive approach. Active cooling can effectively control the excessive thermo-structural deformation and fuel heating below its cracking temperature to improve combustion. Our parametric design study indicates the influence of fuel as a coolant for increasing combustion efficiency and the associated complexity and trade-off in the heat transfer and thermo-structural deformation behavior. This transient response under hypersonic accelerating-cruise flight conditions requires a careful review of the scramjet engine thermo-structural design philosophy. The design approach has applications in bodies encountering highly transient thermo-structural loads with differently purposed fuels/coolants.