Numerical simulation of liquid rocket thrust chamber flows is a challenging task which requires a comprehensive tool validation strategy encompassing laboratory- to full-scale test cases. While the former are widely used as the first step to verify advanced numerical schemes and thermochemical models, the latter can often no more be simulated in a reasonable time frame due to the extreme computational effort necessitated by the enlarged dimensions and configurational changes. Conclusions drawn from tools with such limitations are only of little help for a thrust chamber designer and, hence, ill-posed to adequately tackle the simulation challenges of such a device. This paper discusses the modeling demands for numerical thrust chamber flow simulation tools and outlines the indispensable validation approach from laboratory- via subto full-scale configurations using consistent model features throughout the test cases. Consequences of this obligation are exposed to drive the tool setup. Exemplarily, the Airbus DS thrust chamber flow simulation philosophy is presented.

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In view of future film cooling tests at the Institute for Flight Propulsion (LFA) at Technische Universität München, the Astrium in-house spray combustion CFD tool Rocflam-II was validated against first test data gained from this rocket test bench without film cooling. The subscale rocket combustion chamber uses GOX and kerosene as propellants which are injected through a single double swirl element. Especially the modeling of the double swirl element and the measured wall roughness were adapted on the LFA hardware. Additionally, new liquid kerosene fluid properties were implemented and verified in Rocflam-II. Also the influences of soot deposition and hot gas radiation on the wall heat flux were analytically and numerically estimated. In context of reviewing the implemented evaporation model in Rocflam-II, the binary diffusion coefficient and its pressure dependency were analyzed. Finally simulations have been performed for different load points with Rocflam-II showing a good agreement compared to test data. List of symbolsTurbulent kinetic energy (m 2 /s 2 ) L Ã Characteristic length (m) _ m inj Injected mass flow (kg/s) _ m Total mass flow (kg/s) M Molar mass (kg/kmol) O/F Mixture ratio [-], O = F ¼ _ m Oxidizer _ m Fuel P c Chamber pressure (bar) _ Q int Integral heat load (kW) R a Mean roughness index (lm) T Temperature (K) V Volume of diffusion (-)