Influence of longitudinal wind on mass burning rate of rectangular heptane pool fire with different aspect ratios: Fid-Bau Portal

Influence of longitudinal wind on mass burning rate of rectangular heptane pool fire with different aspect ratios

Li, Manhou / Li, Ranran / Han, Guangzhao / Guan, Jinfu

Graphical abstract The variation of fuel consumption rate with longitudinal flow velocity and aspect ratio is summarized. At v < 0.96 m/s, the mass loss rate increases with an increase in wind speed, regardless of aspect ratio. The mass burning rate reaches the maximal value at v = 0.96 m/s. The consumption rate of fuel decreases considerably at 0.96 ≤ v < 1.98 m/s and then fluctuates slightly at 1.98 ≤ v < 2.49 m/s. In summary, the burning rate of rectangular pool fire versus longitudinal wind speed is divided into three regimes: (I) the increasing regime at v < 0.96 m/s, (II) the decreasing regime at 0.96 ≤ v < 1.98 m/s, and (III) the slightly-fluctuating regime at 1.98 ≤ v < 2.49 m/s. Mass burning rate as a function of longitudinal wind speed and aspect ratio. Display Omitted

Highlights • Mass burning rate versus aspect ratio and wind speed is quantified. • Variation of mass burning rate is analyzed by fuel evaporation theory. • The proposed model $Δ \dot{m} / k^{'} = (2 \sqrt{n} + \frac{1}{\sqrt{n}}) v$ is used to correlate burning rate. • The measured mass burning rate follows well with new-proposed model.

Abstract Fire is one of the primary disasters that threaten the safe operation of tunnel and underground space. Mass burning rate is a significant parameter in characterizing the behavior of pool fire which is related to thermal feedback, pool shape and ambient wind. Five convection-controlled heptane pool fires are examined inside a longitudinal wind tunnel with aspect ratio of 1, 2, 4, 8, and 16. The variation of burning rate with longitudinal wind is divided into increasing regime at v < 0.96 m/s, decreasing regime at 0.96 ≤ v < 1.98 m/s, and slightly-fluctuating regime at 1.98 ≤ v < 2.49 m/s. The effect of longitudinal wind on burning rate is attributed to heat feedback, flow disturbance and oxidizer supply around the flame. The increment of burning rate with wind speed is proved by the liquid evaporation theory. The heat transfer analysis proves that the enlargement rate of burning rate is linearly proportional to a coupling factor of longitudinal air flow speed and aspect ratio in a unified mathematical correlation $Δ {\dot{m}}^{″} / k^{'} = (2 \sqrt{n} + \frac{1}{\sqrt{n}}) v$ which is fully consistent with measurements. The results provide guidance for tunnel fire protection design and prediction of fire development under the condition of vehicle tank leakage inside a tunnel.