CFD modelling of confined jet fires under ventilation-controlled conditions

This paper presents field predictions for two confined jet fires under vent ilation-controlled conditions. Three different combustion models, namely th e laminar flamelet model, the constrained equilibrium (CE) method and the e ddy break-up (EBU) model, are used and compared. The laminar flamelet model and the CE method are coupled with Lindstedt's soot model, while the EDU m odel is coupled with the soot model of Magnussen. The global radiative heat exchange is considered by using the discrete transfer radiation method (DT RM) and the calculation of the microscopic radiative heat exchange within t he flamelet is embeded in RUN-1DL. For both the flamelet and CE methods, th e energy equation is solved so that the radiation calculation is coupled wi th the computation of the turbulent combustion processes. Comparisons are m ade between the experimental data and the predictions of different submodel combinations for two propane jet fires in enclosures of 135 and 415 m(3). It is found that all the sub-model combinations predict the correct trends of distributions for field variables such as velocity, temperature, soot, a nd CO. The predicted temperature distributions from the flamelet approach, which includes both the microscopic and global radiative heat losses, are f ound to be in close agreement with the experimental data. Modifications are made to the convective heat transfer coefficients between the wall and the gaseous products in the impinging region and this is found to have improve d the predictions for the wall heat fluxes. (C) 2000 Elsevier Science Ltd. All rights reserved.