Effusion Cooling in Rocket Combustors Applying Fiber Reinforced Ceramics

Abstract

Since 1994 DLR has focused its efforts on combustion chamber technologies within the internal program "High Pressure Rocket Propulsion" (HDR). The main emphasis lays on advanced cooling technologies and especially effusion cooling applying fibre reinforced ceramics as porous media and hydrogen as cooling fluid. This paper summarises the recent experimental work on this cooling technique using Carbon/Carbon (C/C) material for combustion chamber components. After a brief summary of the fabrication process of the specific ceramic and the material properties, the basic equations for the flow situation and appropriate models are presented. Within the experimental campaign which has been performed at the DLR micro combustor facility M3 the combustion chamber pressure has been varied between 0.3 MPa and 1.1 MPa at a constant oxidiser/fuel mixture ratio of 6.5 using ambient hydrogen as coolant. The porosity of the ceramics has been varied in the range from about Epsilon = 13% to Epsilon = 25% in order to optimise the coolant mass flow rate and pressure loss across the porous wall. A wide range of coolant mass flow rates has been tested in order to achieve a broad data base for modelling an check the limits of applicability of the cooling technique and the ceramic wall material. The paper concludes with a presentation of experimental and theoretical results and a brief outlook to future activities.