CHEMICAL KINETICS AND INJECTION MODELING FOR HP LOX/CH4 JET FLAMES

The aim of the present work is to compare different approaches for modeling combustion in cryogenic LOx/CH4 rockets. The oxidizer is liquid oxygen, delivered to combustion chambers as a spray of droplets; the fuel is gaseous methane. Pressure and temperature are well above thermodynamic critical points of both the propellants and so the reactants show liquid-like characteristics for density and gas-like characteristics for diffusivity. A so complex behavior leads to some difficulties in choosing the most appropriate modeling approach for phenomenon description. In literature it is possible to find a large number of experimental works concerning cryogenic combustion of liquid oxygen and gaseous hydrogen under sub-critical and trans-critical conditions but also for methane as fuel. In the present work LOx-methane combustion for G1 and G2 cases of RCM3-VO4 test plane of ONERA have been investigated to compare different approaches in numerical modeling of cryogenic flame. The most important aspects taken into account are combustion models, kinetics descriptions and thermodynamic properties. The Eddy Dissipation combustion model and the Probability density function PDF model were compared; the Jones- Lindstedt and the Skeletal mechanisms were used for kinetics description for the Eddy Dissipation model; for thermodynamic approach, in the current work gas was modeled using both ideal gas and real gas equation of state (Peng-Robinson and SRK) and liquid oxygen was treated with a Lagrangian approach in a hybrid Eulerian- Lagrangian approach for mixture. Numerical predictions were compared with experimental data from literature.