Experimental study on transpiration cooling with phase change in rotating detonation engine

Abstract

Transpiration cooling with phase change is an effective method for protecting high heat flux walls from ablation in combustion chambers and spaceflight vehicles. The combustion chamber walls of the rotating detonation engine (RDE) experience high heat flux, which poses significant challenges to thermal protection and limits its development. This study introduces a transpiration cooling thermal protection system for a kerosene/air RDE, where the liquid coolant absorbs heat with phase change, reducing wall temperature by more than 50% under certain conditions. The experiments investigated the effects of coolant flow rate, coolant types (water and kerosene), porosity of porous media, and fuel equivalence ratio on both transpiration cooling and detonation wave dynamics. The results show that water provides superior cooling effectiveness compared to kerosene, particularly with increased flow rates and porosity. During RDE operation, increasing flow rates of both water and kerosene initially enhances cooling efficiency but eventually leads to an overall reduction. Furthermore, higher coolant flow rates of both water and kerosene can disrupt the stability of detonation waves within the combustion chamber. Although enlarging the equivalence ratio improves cooling efficiency, maintaining continuous detonation wave generation remains challenging. The cooling efficiency in the detonation combustion mode is lower than that in deflagration. Additionally, carbon deposition was observed in the transpiration cooling system, particularly during prolonged operation. These findings provide valuable insights for the optimization and technical guidance of RDE design.