Numerical investigations on the effect of cross wind on the flow field and the mass loss rate of the fuel in a compartment fire with two opposing openings

This paper investigated the impact of the cross wind (wind blowing vertically into the compartment through the window) on the flow field and heat feedback in compartment fires with two opposing openings. This study was conducted through theoretical analysis and numerical simulation. A square heptane pool was placed inside a fullsize cubic room model with a side length of 3 m, serving as the fire source. Four pool sizes (0.30 m, 0.40 m, 0.46 m, and 0.52 m) were used in combination with cross wind speeds ranging from 0 to 5 m/s in the simulation. The results indicate that as the pool size and wind speed increase, the rate of fuel mass loss also rises. When the wind is present outside the compartment, it obstructs the outflow of hot gas from the window, as if the window is "sealed". This accumulation of hot gas inside the compartment leads to increased radiative heat flux absorbed by the fuel and an elevated mass loss rate. When the wind speed surpasses the critical threshold for wind speed, the airflow at the door transforms from bidirectional flow to unidirectional flow. The critical wind speed determined for all scenarios in this study ranges from 2.5 to 4.5 m/s. A coefficient alpha, which represents the impact of cross wind on the mass loss rate of fuel in a compartment fire (compared to the case without wind) was defined. Based on dimensional analysis, the correlation between alpha and wind speed was established.