Multi-fidelity Data Ensembles of Liquid Phase Rocket Ignition: Ignition Limit States and Reliability

To understand the reliability of successful ignition through use of laser energy deposition for a liquid-oxygen gaseous-methane rocket combustor, we conduct large-eddy simulations (LESs). We first ensure that pre-ignition flow statistics accurately reproduce companion experimental measurements conducted at Purdue University. With satisfactory agreement observed in pre-ignition, we vary physical input parameters to construct an ensemble of LES ignition trials. The majority of the computations are coarse LES but a small set of enhanced refinement calculations with an order of magnitude more grid points verify that the ignition mechanism is the same across fidelities. Subsequently, alignment between experiments and simulations is enabled by a parameter estimation framework, whereby unmeasurable quantities associated with the laser operation are inferred by the uncertainty in underlying successful ignition likelihoods that arises from a limited number of experimental trials. With confidence established in the LES, we subsequently report the ignition pathways contrasting the critical instances that lead to ignition failure or success.