CFD analyses of effusion cooled combustion chambers

All over the world, rocket engine design engineers are faced with an ever increasing demand for higher performance and reliability as well as reduced cost. In order to improve the efficiency of current state-of-the-art core engines, operating at combustion chamber pressures above 10 MPa, a hot gas pressure of up to 25 MPa is desirable. In consequence of the proportional increase of the heat transfer from the hot gas to the chamber wall at such high pressure levels, alternative cooling methods to the conventional regenerative cooling are proposed to ensure the thermal protection of the chamber liner. Effusion cooling of a porous combustion chamber wall made of carbon fiber reinforced carbon (C/C) seems to be one of the most prospective techniques to fulfill this requirement. Due to the high temperature resistance of this material, the demand of coolant fluid to protect the liner and therefore the pressure drop in the coolant supply system is minimized. A constant improvement of the material characteristics and an optimization of the design of the combustion chamber wall with respect to the coolant distribution should lead to an acceptable coolant demand for a practical application of this technology. Following this approach, numerical analyses have been performed with the objective of a better understanding of the coolant flow dynamics inside the porous wall and the coolant - hot gas interaction at the wall outlet.