Effect of vertical facing wall on facade flame height of under-ventilated compartment fire with triangular opening

The present paper investigated the evolution law of the facade flame height for under-ventilated compartment fires with triangular openings constrained by a vertical facing wall. Through a series of reduced-scale experiments, the hot gas temperature inside a compartment was measured by thermocouples, and the facade flame height was obtained by processing the sequential images of the facade flame recorded by a CCD camera. The results revealed that the vertical facing wall has little effect on the hot gas temperature inside the compartment, and the facade flame height is independent of the vertical facing wall when the distance between the triangular opening and the vertical facing wall (D) is relatively large, while the facade flame height is increased at a relatively small D. The facade flame height for triangular opening with a vertical facing wall is unable to be characterized by the classical model of the rectangular opening. Based on the balance of momentum and buoyancy at the opening, a characteristic length of L₃ was proposed to describe the effect of a vertical facing wall. By introducing a correction factor κ related to L₃ and D, a new global model was finally established to predict the facade flame height for triangular openings with and without a vertical facing wall. This work extends the knowledge about the hazard of compartment fires involving triangular openings to the cases with a vertical facing wall.