Transpiration Cooling Applied to C/C Liners of Cryogenic Liquid Rocket Engines

Abstract

The state–of–the–art of ceramic matrix composites (CMC) utilization in liquid rocket engines is briefly reviewed. System analysis studies into the performance of transpiration cooled thrust chamber liners reveal coolant mass flow rates to be feasible only if they do not exceed 0.7% of the engine mass flow rate. Experimental studies clearly show that common models for heat transfer descriptions of blowing boundary layers are not able to predict precisely enough the cooling efficiency along a transpiration cooled liner. Instead a mixed approach, partly experimental and partly numerical, has been employed. A 2–D CFD tool based on the commercial ANSYS program has been adapted to model the compressible flow through the porous structure in order to predict the coolant mass flow distribution along a C/C liner and has been verified with experimental studies. To ensure the thermal protection of the C/C liner a minimum necessary coolant demand of around 0.45% of the total chamber mass flow rate has been calculated with TDK. A mathematical optimisation procedure is presented which should predict the necessary material properties to optimise the design of the liner’s micro–structure for the specific transpiration cooling requirements.