Flame whirling characteristics of fire in a room with vent

Velocity distribution and motion of a whirling flame in a room fire with vent were studied analytically in this article. Using Rankine vortex model, whirling flame models with and without decay of the rotation velocity were established. The whirling flame model and the cross-wind velocity boundary conditions were used to study the velocity distribution of the rotating flame under the action of side wind. When there is a linear velocity gradient in the lateral wind, the whirling flame still revolves around the same axis at different heights in the model without attenuation of rotation velocity, but the axis becomes tilted. In the rotation velocity attenuation model, the axis of the whirling flame changes from a straight line to a curve, and the change of the shape of the whirling flame is related to the flame height, the rotation angular velocity, and the maximum wind velocity. Under the assumption of Rankine vortex model with the same rotation angular velocity, the uniform lateral wind and lateral wind with linear velocity gradient can only affect the position and shape of the whirling flame axis but not change the rotation angular velocity.