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Experiments were conducted to characterize the effects of crosswind on flame properties for unconfined fires. Propane gas was used as a fuel in a O.lm XO.lm diffusion burner employed as a model fire source. The effects of the floor around a fire source, which would control the volume of air entrained into the hot current, were also investigated. Empirical models of the apparent flame height of the inclined flame are presented. We also develop empirical models of the flame tilt angle based on the balance of mass fluxes given by the upward hot current and crosswind. These models are based on functions of dimensionless heat release rate and Froude number. The values of empirical coefficients and exponents were derived from the experimental results. The calculated flame length based on the flame tilt angle and the apparent flame height was compared with experimental results, showing that models can be used to estimate flame length in crosswinds .

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This paper describes a series of fire experiments in a 0.9m by 0.6m by 0.4m high compartment. A single rectangular opening is set for the ventilation with opening factors (AH 0.5) ranging from 0.02 m 5/2 to 0.10 m 5/2. Propane gas and three kinds of solid fuel (wood crib, PMMA and polyurethane flexible foam) are used as fuels. Mass loss rates are measured and net heat release rates are estimated with a furniture calorimeter to examine combustion efficiency, which effects ejected flame formation. Results indicate that the combustion efficiency of gas fuel depends on 'fuel to air' global equivalence ratios (Φ) and the efficiency starts to decrease at about the 0.75 of Φ. Moreover, the efficiency reaches 77 % when Φ is at 1.27. However, when more fuel is supplied, the efficiency is improved to 100 % at the 2.0 point, because combustion is promoted within externally ejected flames. In the case of solid fuels, maximum heat release rates become 1.5 to 2.5 times higher than the suppositional maximum heat release rate determined by the opening factor. Under these cases, flames are ejected longer and the efficiency of the combustion also recovers as well as gas fuel combustion.

Experiments were performed to investigate the effects of the shape and size of a fire source on fire properties using a tunnel model with a rectangular cross section and aspect ratio of 1:2. Square and rectangular burners were used as the model fire sources. The variations in the heat release rate (HRR) from 4.5 to 36 kW was proportional to the fire size, and the longitudinal ventilation velocity was also varied in the range from 0 to 0.8 m/s. The flame tilt angle, maximum temperature rise of the smoke layer near the ceiling and its position were adopted as the variables that characterise the fire phenomena in the near field of a fire source in the presence of longitudinal ventilation. New empirical formulae considering the effects of the shape and size of a fire source on these variables were developed.