Heat transfer and mathematical model of flame geometry of rectangular-shaped pool fire in longitudinal ventilation tunnel

Fire is one of the most serious threats in operation of the tunnel. The thermal radiation disaster of fire is dependent on flame height and inclination angle which are affected by the longitudinal ventilation. The coupling effect of aspect ratio of rectangular container (n = 1, 2, 4, 8, 16) and longitudinal wind on flame geometry of heptane pool fire are revealed. The flame height decreases with an increase in the wind, while the inclined angle increases in longitudinal winds of 0–2.49 m/s. The variation of flame geometry is interpreted using the mechanical equilibrium of horizontal inertial force and gas uprising buoyancy induced by liquid fire. According to air entrainment theory and heat feedback theory, the flame height and inclined angle of rectangular-shaped fire change with characteristic scale ratio (n+1n) in mathematics. The measurements of flame height and inclined angle are analyzed and several quantitatively mathematical equations incorporating heat release rate, characteristic scale ratio, non-dimensional burning rate, non-dimensional air flow are proposed. The predicted results of flame geometry are fully validated by experimental measurements. The current finding is convenient for establishing radiation model of pool fire in air-blown condition.