Multi-Phase Impact on the Heat Load Characteristics of a Multi-Element Methane-Oxygen Rocket Thrust Chamber

•Extension of a timescale based non-adiabatic flamelet model with multi-phase data.•3D conjugate heat transfer simulation of a sub-scale rocket thrust chamber.•Condensation at the combustion chamber wall affects the local wall heat load.•Comparison with experimental data delivers a very good agreement. Aiming at the capability to numerically model relevant operating conditions in rocket thrust chambers, this research work introduces a real gas multi-phase data extension to investigate the impact of water condensation within a widely studied sub-scale research test case. Following a dense gas approach and embedded into a state-of-the-art timescale based frozen non-adiabatic flamelet combustion model able to capture the characteristic hydrocarbon chemical reaction and recombination phenomena, the pre-computed manifold incorporates the underlying physical processes to describe the properties of the fluid mixture. The modeling framework is initially evaluated against simplified non-reacting experimental studies of water condensation along a cooled wall structure in the presence of non-condensable gases to confirm its ability to predict the phase change impact on the wall heat transfer. The good agreement with experimental heat load data is further confirmed in the frame of a conjugate heat transfer simulation of a multi-element methane-oxygen rocket thrust chamber, for which the design of the regenerative cooling system leads to localized condensation effects as the wall temperature remains below saturation conditions. The associated release of the formation enthalpy coupled with a change of the fluid properties captured by the newly developed model formulation leads to higher wall heat loads compared to the numerical predictions of an ideal gas single-phase model.