Modeling the trajectory of window flames with regard to flow attachment to the adjacent wall

Abstract

A model for predicting the trajectory of window flame ejected from a fire compartment was formulated incorporating the effect of wall above the opening. Based on the observation in the reduced scale experiments, window flames were divided into following categories with regard to its trajectory configuration: the flow which ascends almost vertically up after ejection maintaining a certain separation from the wall; and the flow which ascends upward after ejection and gradually approaches to the wall in the downstream. In the model, trajectories of these flows were approximated by cubic polynomials whose coefficients were given as functions of a dimensionless parameter * F. The parameter * F was derived from the conservation equation of momentum which incorporates the effect of pressure gradient across the ascending flows. Critical condition for the occurrence of flow attachment was described as a proportion of the maximum separation from the wall versus the opening width. Trajectories predicted by the proposed model were then compared with the measurement data which indicated reasonable agreements.

Development and validation of a physics-based urban fire spread model

“…Although the mechanism of burn-through is intrinsically complex, we now assume that it initiates when the accumulation of the incident heat flux exceeds a critical value Q 00 cr . Then the time at which the burn-through initiates t takes the form Z t 0 _ q 00 M dt4Q 00 cr (19) where _ q 00 M is the incident heat flux. The model in Eq.…”

Effects of side walls on facade flame entrainment and flame height from opening in compartment fires

“…Such a restriction of side walls on enclosure facade fires mainly focusing on the effects of side walls on temperature distribution has been reported in [18]. Because the presence of side walls does not affect the critical heat release rate (1500A √ H , in kW) [19][20][21][22], the main effect on the facade flame height is presumably due to the restriction of air entrainment from the two sides parallel to the facade wall. This effect of side walls on facade flame entrainment and thus the facade height behavior is investigated in detail in this work.…”

Heat flux profile upon building facade due to ejected thermal plume from window in a subatmospheric pressure at high altitude

“…Extensive works [9][10][11][12][13][14][15][16][17][18][19][20][21] have been performed to address the characteristics of such facade flame ejecting behaviors. Yokoi [9] carried out the earliest research on window-ejected buoyant thermal plume characteristics for enclosure fires and established the spill fire plume dimensionless temperature distribution model, in which the compartment size was 0.4 m × 0.4 m × 0.2 m. Oleszkiewicz [10] conducted a series of full-scale experiments with different window dimensions and heat release rates (HRRs).…”

“…Cheng and Hadjisophocleous [12] studied the impact of different window sizes, separation distances between the fire building and a target wall, and different fuels on radiation heat fluxes on the target wall and proposed a modeling of radiation heat flux on the target wall from post-flashover compartment fire. Himoto et al [13] have performed theoretical and experimental analyses to predict the trajectory of window-ejected flame from a fire room. Lee et al [14] have proposed a new non-dimensional flame height and heat flux formula, considering the window dimension effect.…”