Numerical Analysis of Methane-Oxygen Liquid Rocket Engine Nozzle Performance with Finite-Rate Chemical Kinetics

This study is devoted to the numerical investiga- tion of finite-rate chemical kinetics within methane- fueled liquid rocket engine nozzles. Two distinct ref- erence test cases have been adopted: the SpaceX Raptor and a JAXA 30kN-class engine. Specific impulse computations show significant disparities among frozen, finite-rate, and equilibrium chemistry models. While finite-rate kinetics yield the best agreement with nominal data, frozen simulations tend to underestimate engine performance. Con- versely, similar outcomes are found across finite- rate and equilibrium simulations, especially for the Raptor engine. A parametric study further elucidates the influence of engine size, combustion chamber pressure, and expansion ratio on performance, re- vealing their impact on thermochemical equilibrium attainment. Notably, increasing chamber pressure and engine size align more closely with equilib- rium, while higher expansion ratios diverge from this trend.