Developing a model of the radiating surface of a flame over a flammable liquid spill in the presence of wind

Abstract

The object of the study is a spill fire. The subject of the study is the geometric characteristics of the flame, in particular, the length and angle of inclination. The model of the radiating surface of a flame over a burning liquid spill of an arbitrary shape is constructed. The essence of the approach is that the length of the flame at a given point is equal to the length of the flame at the point of the circular spill located at the same distance from the boundary of the spill. It allows generalizing the known empirical dependences for the case of spills of arbitrary shape. The flame length is a power-law function of the distance to the spill boundary and the mass loss rate per unit area. To take into account the effect of wind on the shape of the flame, the empirical dependence of the length and angle of inclination of the flame on the wind speed is used. It is assumed that the wind deforms the flame in such a way that all points of the flame surface deviate by the same angle from the vertical. Wind inclines the flame from the vertical axis more significantly for the smaller size of the spill and smaller mass loss rate per unit area. This is due to the formation of more powerful upward currents over the combustion center when its size and intensity of liquid combustion increase. A model of the radiating surface of the flame was constructed in a parametric form. The results obtained from the model are in good agreement with the experimental ones. The relative error for the angle of deviation of the flame by the wind from the vertical axis does not exceed 9%. In practice, this opens up opportunities for calculating the thermal impact on nearby technological objects, as well as determining safe zones for the location of personnel and equipment involved in fire suppression. The model can be used to specify the thermal effect of fire on steel and concrete structures.