Transpiring cooling of a scram-jet engine combustion chamber

Abstract

The peak cold-wall heating rate generated in a combustion chamber of a scram-jet engine can exceed 2000 Btu/ft\super{2}sec (approximately 2344 W/cm\super{2). Therefore, a very effective heat dissipation mechanism is required to sustain such a high heating load. This research focused on the transpiration cooling mechanism that appears to be a promising approach to remove a large amount of heat from the engine wall. The transpiration cooling mechanism has two aspects. First, initial computations suggest that there is a reduction, as much as 75 percent, in the heat flux incident on the combustion chamber wall due to the transpirant modifying the combustor boundary layer. Secondly, the heat reaching the combustor wall is removed from the structure in a very effective manner by the transpirant. It is the second of these two mechanisms that is investigated experimentally in the subject paper.