Predictions of free jet fires from high pressure, sonic releases

Abstract

A numerical model for predicting jet fires resulting from high pressure, sonic releases of natural gas is described. The model is based on solutions of the density-weighted forms of the fluid flow equations. It is capable of accurately resolving the near-field shock structure that occurs in these flows through the use of a compressibility corrected version of the k-ϵ turbulence model, and also includes sub-models for the flame lift-off height and a prescribed probability density function/laminar flamelet model of the turbulent non-premixed combustion process. Radiation heat transfer is described using an adaptive version of the discrete transfer method, with solutions of the radiation heat transfer equation obtained using a statistical narrow band approach. The complete model is demonstrated to yield plausible predictions of the structure of both the near-field non-reacting and subsonic combusting zones within wind blown fires, and to provide realistic predictions of flame lift-off heights, mean temperatures, trajectories and the radiation fluxes received about a number of field-scale jet fires.