Comparison of Detailed Chemistry and Flamelet Combustion Modeling in a H2/LOx Subscale Combustion Chamber

Abstract

The accurate simulation of high-pressure combustion phenomena in rocket thrust chambers is one of the key technologies in the development of future launch vehicles. Due to the harsh flow environment inside rocket engines, experimental investigations are difficult and numerical simulations are an indispensable tool for providing more detailed insights into the flow topology and the physical processes in such devices. Recent developments in reusable first stage rocket motors has sparked interest in using methane as fuel which increases the complexity of the chemistry involved. Regarding numerical simulations, such fuel-oxidizer combinations will render detailed chemistry schemes numerically very inefficient and call for simpler approaches like flamelet combustion models. In order to assess the range of validity of flamelet combustion models, this work compares experimental and numerical results for a H2/LOx subscale combustion chamber at supercritical pressures. For the particular case of H2/LOx combustion, a comparison between a detailed chemistry and a flamelet model can be made, especially concerning the assumption of unity Lewis number. In addition to that, the validity of the multi-fluid-mixing assumption (ideal gas mixture rules even for supercritical species) is investigated for different fuel/oxidizer temperature combinations. Numerical simulation results are compared to experimental data from the subscale combustion chamber BKC (Brennkammer C) operated at the DLR Lampoldshausen. These results include wall temperature and chamber pressure measurements, as well as flame length visualizations.