Experimental and numerical investigation of combustion in a hydrocarbon and gaseous oxygen fuelled rocket

Abstract

Turbulent spray combustion in a laboratory scale liquid rocket engine fuelled by a liquid hydrocarbon, gasoline, and gaseous oxygen was studied under both fuel-rich and fuel-lean conditions. Various pertinent parameters, such as pressures at important locations, fuel and oxygen mass flow rates, and thrust were measured during the experimental runs. The steady state values of these parameters were further utilized to calculate the specific impulses and the c∗ efficiencies for the test cases. The experimental values of chamber pressure and the generated thrust were verified by modelling the combustion process in ANSYS FLUENT by using n-heptane as the surrogate fuel. The model was utilized to evaluate the capability of four turbulence models – standard k-ε (SKE), realizable k-ε (RKE), renormalisation group (RNG) k-ε, and Reynold’s stress model (RSM), combined with either a probability density function model using equilibrium chemistry or a steady diffusion flamelet model with a detailed chemical kinetic mechanism. Although the RSM model combined with the flamelet model was found to be the most realistic in prediction of the essential features of turbulent spray combustion in a liquid rocket engine, the SKE model combined with the flamelet model was found to predict the experimental pressures most accurately.