Flame projection lengths of horizontally oriented buoyant jet fires under different air pressures

A horizontal buoyancy-controlled jet fire forms when a gaseous fuel leakage occurs in a pipe or a fuel tank and the fuel is ignited. In this study, the horizontal flame projection length (Lph) from such fires was experimentally investigated under different ambient air pressures. The experiments were conducted at air pressures in the range of 50–100 kPa, and methane was used as the fuel. The experimental results indicated that the flame projection length (Lph) increases with an increase in the heat release rate (Q) and decreases with the increasing ambient air pressure. The relationship between the flame projection length and the atmospheric pressure can be expressed as Lph∝P−0.6. The burner diameter (d) and flame projection length (Lph) were regarded as the characteristic lengths to characterize the fuel momentum and the flame buoyancy force, respectively. It was found that the non-dimensional flame projection length (Lph∗(P0/P)−0.6) can be correlated with the modified flame Froude number (Frf) under different air pressures, and the correlation can well unify the results of this study