An elementary model for an advancing autoignition front in laminar reactive co-flow jets injected into supercritical water

In this paper we formulate and analyze an elementary model for the propagation of advancing autoignition fronts in reactive co -flow fuel/oxidizer jets injected into an aqueous environment at pressures exceeding the critical point of water. This work is motivated by the experimental studies of autoignition of hydrothermal flames performed at the high pressure laboratory of the NASA Glenn Research Center. Guided by experimental observations, we use several simplifying assumptions that allow the derivation of a simple, still experimentally feasible, mathematical model for the propagation of advancing ignition fronts. We analyze the model by means of asymptotic and numerical techniques and discuss feasible regimes of propagation of advancing ignition fronts. We hope that the present study will be helpful for the interpretation of existing experimental data and guiding of future experiments.