Prediction of explosion pressures in confined spaces: Fid-Bau Portal

Prediction of explosion pressures in confined spaces

Pritchard, D.K. / Freeman, D.J. / Guilbert, P.W.

The developement of the CFDS-FLOW3D explosion code and the associated programme of experimental validation work have resulted in close agreement between experimental results and simulations, for a range of cases, including both confined and vented explosions. The experimental results, in particular the high-speed video pictures of the development of the explosions, gave insight in the early failings of the model and led to significant improvements. These improvements have led to results which not only reproduce the pressure values well but also demonstrate the correct behaviour of the propagation of the flame front. It is always important, however, to continually test the model against further experiments. Further work will include experiments in a wider range of geometries, with different obstacles. The restriction of the model to open geometries, i.e. systems which can be completely resolved geometrically, has already been mentioned. In order to model explosions in larger structures, it will be necessary to include models for sub-grid-scale obstacles. These models are complicated and require as a prerequisite a good model for open regions, since the correlations needed for flame propagation in a congested region depend on knowing the behaviour of the flame around the objects which are not resolved. Further work on modelling open geometries is required before accurate sub-grid models can be developed. In particular, the turbulence model has been shown to have significant effect on the predicted explosion overpressure. In addition, no account has yet been taken of the enhanced quenching near to walls, the effects of which have been highlighted by the confined explosions within the flameproof enclosure.