Experiments on Nitrogen and Hydrogen Transpiration Cooling in Supersonic Combustion Ramjets (Scramjets)

One of the main challenges concerning scramjet propulsion systems is the efficient and sufficient cooling of the engine’s components. A promising cooling approach could be the method of transpiration / effusion cooling, where the coolant flows through a porous wall prior to entering the engine’s main hot gas flow. This could establish a homogeneous and protective coolant layer at the engine wall, protecting the areas with high thermal loads and the engine structure from thermal damage. The Institute of Space Propulsion of the German Aerospace Center (DLR) has developed a research test bench to investigate the applicability of transpiration cooling systems to scramjets. This publication compares and summarizes the results on cooling performance using nitrogen and hydrogen as coolants. Findings with and without shock generator are opposed to each other. Further research requirements are discussed