Numerical simulation of forced ignition of jet-fuel/air using large eddy simulation (LES) and a tabulation-based ignition model

A comprehensive computational model for forced ignition is used to simulate a canonical experiment for the high-altitude relight process. The focus here is on simulating the ignition probability for a given set of operating conditions. In particular, the effect of fuel composition on the ignition characteristics is studied. Forced ignition using an external igniter involves the interaction of chemical kinetics, turbulent flow, and the uncertainties associated with the igniter energy deposition process. In this work, a detailed model for the growth and stabilization of the hot kernel produced by the igniter is used. Large eddy simulation (LES) is used to describe the turbulent flow and the fuel-air concentration fluctuations, as well as their temporal evolution. Ignition is described as a probabilistic event, with the randomness a result of the uncertainties in turbulent state of the system and the igniter energy deposition. Using an uncertainty quantification approach, the ignition probability is estimated for three different fuels. It is shown that the model correctly reproduces the ignition trends observed in the experiments. Moreover, it is demonstrated that uncertain parameters may be calibrated using related experiments and extended to other operating conditions.