A study on fire plume behaviour in cross-winds.

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On the basis of the experimental study using a single fire source and/or multiple fire sources focusing on the flame shape and fire plume behavior in the presence of crosswinds, the following conclusions were obtained.(1)Dimensionless formula for the apparent flame height of an inclined flame under the influence of cross-wind has been developed based on the modified dimensionless heat release rate, Froude number and equivalent length of burner. An empirical formula also has been developed to predict the flame tilt angle considering the burner shape. This model is derived from the balance of mass fluxes of wind and hot current, combined with centreline properties of a fire plume.(2)An empirical formula for predicting the position of an inclined fire plume axis by applying the logistic function including the variables expressed by the combination function of heat release rate and crosswind velocity was proposed. A new formula for estimating the velocity along the inclined fire plume axis … More using the values of the temperature rise, crosswind velocity and travelling distance was developed based on the assumption that there is a virtual ceiling at the upper limit of the height that the hot current can reach. Further, the behaviour of this hot current, influenced by the crosswind, closely resembles the ceiling jet that flows under this virtual ceiling. This correlation is useful, and it is applicable for the estimation of the velocity along the fire plume axis irrespective of the presence of a crosswind.(3)The section shape of the inclined fire plume was experimentally clarified based on the plume width defined by temperature. In addition, it was shown that the temperature distribution in the inclined fire plume was expressible as the sum of two kinds of Gaussian distributions, one is temperature distribution directory carried from the fire source and the other is carried from the upstream by the cross-winds.(4)The reproducibility of the fire plume properties in the cross-winds was examined by using two kinds of CFD codes. It became clear that the height of the continuous flame and the position of the fire plume axis were able to be reproduced to some degree by applying the combustion model and by devising the method of setting the heat release rate. Two kinds of CFD codes showed mutually different results. Moreover, the temperature decreasing properties along the inclined fire plume were different with the experimental results.(5)The empirical formulae for predicting the apparent flame height, the position of an inclined fire plume and the temperature decreasing along an inclined fire plume for a single fire source were examined whether it was possible to apply by comparing them with the experimental results with multiple fire sources in cross-winds. Less