Experimental and numerical evaluation of the influence of the soot yield on the visibility in smoke in CFD analysis

Experimental and numerical analysis have been performed to evaluate the influence of the soot yield parameter on the results of advanced engineering analysis, in regards to visibility. After identifying soot yield as the most influential factor on the results, fuels with various values of Ys have been analysed in a fire chamber and then compared to numerical data. The numerical analysis has been performed using two different CFD packages, ANSYS® Fluent®, and Fire Dynamics Simulator. The numerical analysis itself show an apparent hyperbolic trend of the visibility when changing the soot yield with clear consequences on the ASET (Available Safe Egress Time). Below a cut-off point, that exists at a soot yield value close to Ys =0,10 g/g, a small change in the parameter causes a substantial shift in the results (visibility or ASET time), while above this value an increase to soot yield does barely influence the results. Qualitative assessment of the results shows a need for use of conservative values of Ys in engineering analysis if detailed and precise material data is not available. Additionally to the full-scale experiments, a real case study has been included to show how this research can be translated into the Fire Safety Engineering design process. In this study, change of Ys value below 0,10 g/g caused a significant change of the qualitative assessment of the results of CFD.