Toward Numerical Investigation of Ignition and Combustion Transition in a Subscale LOX/Methane Rocket Combustor

LOX/methane is a promising alternative to hypergolic fuels in spacecraft thrusters, featuring advantages such as nontoxicity, high specific impulse, and low cost. Its reliable ignition, however, is a challenging problem due to its dependence on the local mixture composition, its requirement of overcoming ionization energies, and its process of transition to a sustained combustion mode. Experimental research has focused on laser pulses as an ignition mechanism for these thrusters, and has demonstrated significant viability. This work presents a numerical study of a reacting LOX/methane thruster using large eddy simulation combined with a Lagrangian description of the LOX spray. This model is successfully employed to simulate reacting flow in the Reaction Control System (RCS) breadboard combustor at DLR, achieving spray behavior that is qualitatively similar to the pre-ignition experimental data. This work represents a forward step towards simulating the startup process of this thruster via laser ignition.