On the production of light by heat

Abstract

The main geometrical features of horizontal jet fire with rectangular source fuel have seldom been revealed in the past, especially the rectangular orifice with same area but different aspect ratios. In order to better understand the rectangular jet fire, a set of numerical simulations were carried out by rectangular source fuel with same rectangular orifice area S (4 cm2) but different aspect ratios (orifice length to orifice width: L/W = 1, 2, 4) to investigate the flame shape, flame length and flame width. The simulated flame lengths and flame widths were compared with previous experimental data and calculated values using the Thornton model. The non-dimensional flame length and flame width were defined, in which the flame geometrical features were found in relation to the orifice aspect ratio and fuel jet velocity. Results show that the flame length and flame width increases with fuel jet velocity, while the flame length decreases with aspect ratio n for same orifice area, but the flame width increases simultaneously. The simulated data agree well with previous experimental data, but the predictions by Thornton model are larger than simulated and previous experimental values. The modified Thornton model is proposed considering both orifice shape and aspect ratio to apply to rectangular jet fire.