EXPERIMETNAL STUDY ON BURNING BEHAVIORS OF LIQUID FUELS WITH DIFFERENT SOOTING LEVELS AT HIGH ALTITUDE

Author: Liu, J. H., Li, P., Chen, M. Y., Chen, X., Yuen, R., Wang, J.

Journal: Thermal Science

Keywords: burning intensity, high altitude, pool fire, sooting level, low air-pressure, heptane pool fires, combustion characteristics, n-heptane, crib fires, scale, plumes

Abstract:

To validate the feasibility of classical fire scaling laws under low pressure, three typical liquid fuels with different sooting levels, i.e. ethanol, n-heptane and jet-A, were employed in this paper to perform a sequence of pool fires in a high altitude city, Lhasa, Tibet, China (3650 m, 64.3 kPa). Mass loss, axial temperature profile and radiative heat flux were recorded in each test. From the assessment of experimental data, it can be concluded that the dimensionless burning intensity m(over dot) mu/D can be correlated against the Grashof number to different powers for all the three fuels, and the exponent increases with the sooting level of fuels. A correlated relationship expressed as Delta T similar to [z(P/Q)(2/5)](n) can be applied to analyze the axial temperature rises, partitioning flame region, intermittent region and plume region with the modified demarcations, i. e. 0.42 and 1.06. In addition, the averaged fame temperature grows higher with declining sooting level of fuels, while the radiative heat fluxes exhibit the opposite results. Moreover, the measured radiative heat fluxes for different fuels are proportional to LmTf5 and the soot volume fraction apparently increases with the sooting level of the fuels under low pressure condition.