Modelling the throttle effect in a mine drift

The throttle effect is a phenomenon, which may occur during a fire underground, causing unforeseen smoke spread. This paper focuses on the modelling of the throttle effect in a mine drift, using a CFD software. The aim of the paper is to investigate whether the CFD tool is able to predict and reproduce the throttle effect for fire scenarios underground. Experimental data from fire experiments in a model-scale mine drift and modelling results from a CFD model were used during the analysis. It was found that the CFD model was not able to fully reproduce the throttle effect for fire scenarios in a mine drift. The inability was due to the under prediction of the fire gas temperature at the ceiling level and the over prediction of the temperatures at the lower levels. The difficulties occurred foremost during transient periods with high fire growth rates. Given the difficulties in modelling the thermal stratification and the throttle effect, the use of CFD models should be mainly for qualitative analysis. Qualitative analysis could possibly be performed for non-transient and low intensity fires.