Numerical Investigation of Chemical Mechanism Effect in Hydrogen/Methane Film-Cooled Nozzles

Modern high performance liquid rocket engines (LREs) deal with high combustion chamber pressures, leading to large thermal loads. In this context, an active cooling system is mandatory for safe operation of such engines. As regenerative cooling alone could be insufficient, film cooling is commonly exploited to assist the engine cooling system in bearing the thermal loads. The prediction of wall heat flux in such film-cooled thrust chambers, especially at the nozzle throat, is of paramount importance during the design phase both for sizing and safety purposes. Computational fluid dynamics (CFD) simulations are a useful tool in performing such prediction, however chemical reaction mechanisms must be representative of the main flow physics without excessive computational burden. The main objective of the present study is the investigation of the effects of different finite-rate chemistry models in subscale GH2/LO2 and LCH4/LO2 film-cooled nozzle flows. Considered chemical mechanisms encompass both global and skeletal models. Comparisons between open literature experimental data and CFD results are used to compare the efficacy of the selected chemical mechanisms.