Fire spill plume from a compartment with dual symmetric openings under cross wind

摘要

This paper presents a comprehensive theoretical and experimental study on the fire spill plume from a compartment with dual symmetric openings under cross wind. Experiments of spill plume were performed at the outlet of a wind tunnel using a bench-scale compartment with a leeward facade wall and dual symmetric openings. The experimental fire compartment was well-mixed. The effect of wind is theoretically elucidated by derivations on the pressure differences between inside and outside. The neutral planes for the two openings are theoretically formulated and compared with those in single-opening and no-wind case. The formulations of the neutral plane heights are verified by using video image analysis and velocity data regression analysis. Also a new method using the data of wind speed and neutral plane height in no-wind case is proposed to determine the neutral plane heights for higher wind speeds. The results suggest that the neutral plane heights vary monotonically with cross wind speed. Two new length scales with variable neutral plane heights are proposed by theoretical derivations to develop scaling models of spill plume. It is indicated that the new length scales are applicable to correlate the axial plume temperature and the total heat flux along the facade. The radial temperature profiles of spill plumes are well described by a Gaussian function normalized by the temperature radius, which is independent on the wind speed. It is found that wind enhances the air entrainment of spill plume in both the near and far fields, thereby the transition from continuous flame, intermittent flame to buoyant plume is accelerated. The data of total heat flux and temperature distribution along the facade indicate that cross-wind has two competitive effects on the heat transportation from the spill plume to the facade. (C) 2016 Published by Elsevier Inc. on behalf of The Combustion Institute.