Thermodynamic analysis on the performance of hydrocarbon fueled scramjet with inlet active cooling

Implementing active cooling techniques on scramjet inlets has been scientifically demonstrated to minimize thermal deformation and mitigate the shock-boundary layer interaction, but the effect on energy and thermal cycle has not been discussed. This research primarily examines the impact of active cooling on the performance of hydrocarbon-fueled scramjets. The theoretical derivations were conducted, and a model coupled with quasi-one-dimensional conjugate heat transfer was developed to depict the thermodynamic process under active cooling. The scramjet performance was analyzed. This study reveals a total pressure increment created by the heat released and re-added at different Mach numbers. The heat transfer in the hypersonic inlet can contribute to almost 3 % of the propulsive performance, offsetting the increased friction losses due to the cold wall. Optimal wall temperatures maximize the engine-specific impulse at different equivalence ratios. Fuel penalties need to be avoided to prevent significant losses. Active cooling improves the backpressure capability of the isolator, reducing the length of the separation zone by up to 12 % while maintaining the same equivalence ratio. This study suggested a parallel flow of coolant, however, the actual design should match the flow rate and the dimensions of cooling channels.