In addition to their engineering applications, air entrainment rates are useful in the specification of boundary conditions for "free" fires. These fires may occur in quiescent outdoors or in very large enclosures. It may be desirable to limit some computations to the near fire region by means of air entrainment rate specification at an appropriate boundary. We have measured fire-induced flowfield around pool fires in a large enclosure and expressed the results in terms of air entrainment rates. We applied Baum's formulation and McCaffrey's source terms to obtain qualitatively correct predictions of the flow field and the entrainment rates. More recently, we have completed in-situ measurements of the thermal expansion source term and the vorticity source term to compute the fire induced flow field and have obtained better quantitative and qualitative predictions of the fire induced flow field. The results are applicable to improving understanding of the flow field, evaluation of entrainment rates, and to the specification of proper boundary conditions for fire simulations.
Acknowledgements: The work described in this talk is the subject of MS and PhD thesis at Purdue University over the last six years written by Dr. X. C. Zhou. Many useful discussions with Dr. H. R. Baum are acknowledged with delight. We also gratefully acknowledge the financial support provided by the Center for Fire Research at the National Institute of Standards and Technology.