Transpiration Cooling with Supersonic Flows and Foreign Gas Injection

Kurzfassung

The extremely high heat loads within a Scramjet combustor require the use of high-temperature materials combined with efficient cooling concepts. A promising technique is the application of transpiration cooling to CMC materials. A supersonic hot-gas flow test facility is used to investigate this cooling method. The Carbon/Carbon (C/C) samples tested have porosities of about 11 %. The air-flow is electrically heated up to 1060 K total temperature with a total pressure of 3 bar and is accelerated to a Mach number of 2.1 within the test channel. Air, argon and helium are used as coolants for blowing ratios from 0 to 1 %. The surface temperature of the porous wall is measured via thermocouples and infrared thermography. An approach based upon simplified analytical models is being presented to analyze the experimental data of the cooling efficiency. This is shown for elevated temperature conditions in supersonic flows, including the specific thermal situations, which are typically encountered in such high-temperature tests.