Experimental investigation on jet fires hazards in a reduced pressure: Assessment of the main width features

摘要

This work investigates the main width features of jet fires hazards in a reduced pressure. Although previous researchers have paid much attention to main geometrical features in atmospheric pressure, the variation characteristics of flame width features in sub-atmospheric pressures has been rarely studied. Elucidating the distinctions of width in a jet diffusion flame in sub-atmospheric (Lhasa: 0.64 atm) and atmospheric pressure (Hefei: 1.0 atm) is of great importance to understand the physical mechanisms of combustion dynamics. Thus, experiments were conducted with 4, 5, 6, 8 and 10 mm nozzles and propane was used as the fuel. Results have shown that the flame width in both pressures increases by increasing the heat release rate. And the flame width is significantly wider for nozzles with larger diameters in both pressures. The flame width normalized by the flame height in both pressure environments decreases by increasing the heat release rate. However, the results in subatmospheric pressures are significantly lower than that in normal pressure, indicating turbulent buoyant jet flame tends to be thinner in reduced pressure. A physical model was employed to characterize the variation of flame width in both sub-atmospheric and atmospheric pressures. The experimental results, obtained in this work and in previous studies, correlate with a good agreement using the present model. This work is a significant supplement to the flame geometrical features of turbulent buoyant jet fires from previous results.