AN INTEGRAL MODEL OF TURBULENT JETS IN A CROSS-FLOW .2. FIRES

A study of turbulent jets in a cross-flow is completed with the presen tation of a mathematical model capable of predicting the thermal radia tion fluxes received around fires. The model is based on solutions of integral forms of the fluid dynamic equations and contains a one-dimen sional formulation of the k-epsilon turbulence model. The gas-phase, t urbulent non-premixed combustion process is modelled via the conserved scalar/prescribed probability density function approach using the lam inar flamelet concept, whilst soot formation and consumption is includ ed through balance equations for soot mass fraction and particle numbe r density which admit finite-rate kinetic effects. Levels of thermal r adiation received around a fire are obtained using a heat transfer mod el based on solutions of one-dimensional differential equations that s pecify local heat fluxes both within and on the surface of a fire, wit h view factor calculations being used to determine the fluxes received by external objects. The usefulness of the complete model for predict ing the consequences associated with accidental and operational releas es of flammable gases has been assessed by comparing model predictions with data obtained in both laboratory and field scale experiments. In all cases, predictions of the model are shown to be in good agreement with the available data. The complete model is applicable to releases of gas at both subsonic and sonic velocities and, with short computer run times, is ideal for routine use in performing consequence and ris k assessments.