A new-proposed multi-inclined-cylinder radiation model of rectangular pool fire of heptane in longitudinal winds

摘要

A rectangular pool fire may be formed which is essentially affected by ambient wind in open space. In this work, the experimental investigations of flame radiation of heptane fire in longitudinal wind are conducted using five rectangular containers with a constant surface area, and variable length-width ratios of 1, 2, 4, 8, 16. The longitudinal air speeds are 0, 0.71, 0.96, 1.22, 1.47, 1.73, 1.98, 2.24 and 2.49 m/s respectively. Results show that as air speed increases, the incident heat flux increases initially and then decreases afterwards, and the threshold value of air flow is approximately at v = 0.96 m/s. The heat flux is primarily determined by burning rate at v ≤ 0.96 m/s whereas it is determined by the combination of flame morphology and burning rate at v > 0.96 m/s. The theoretical formula of radiation emissivity of rectangular pan is deduced using mass burning rate and aspect ratio. The multi-inclined-cylinder model incorporating aspect ratio, flame height, tilt angle and mass burning rate is proposed to evaluate the rectangular flame radiation in air flows. The theoretical values of heat fluxes are acceptably consistent with measurements in longitudinal wind-blown condition.