On extinction of hydrothermal flames in laminar reactive jets

Abstract

In this paper we formulate and analyze an elementary model for the extinction of hydrothermal flames in laminar reactive jets experimentally observed in an aqueous environment at pressures exceeding the critical point of water. This work is motivated by experimental studies of the dynamics 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, yet experimentally feasible, mathematical model for the hydrothermal flame extinction. The analysis of the model shows that the principal parameters of the problem determining flame extinction are Damköhler number and the injection velocity of the reactive components. In particular, we formulate a sharp condition for the extinction of hydrothermal flames in terms of Damköhler number. The results of the present study may assist in the interpretation of existing experimental data and provide guidance for future experiments.