The burning behaviors of pool fire flames under low pressure

Summary To investigate the influence of low pressure on pool fire behaviors, liquid n-heptane pool fires with the diameters of 6, 8, and 10 cm were tested in a low-pressure altitude chamber. The tests were conducted under different static chamber pressures, ranging from 40 to 60 to 80 to 101 kPa. Fuel mass loss and high-speed flame video were recorded during the whole burning process of each test. The mass burning intensity is determined by the convective and radiative heat feedback to the fuel, and analysis shows that the convective part is the major contributor to fuel evaporation. Video recordings show that flame height increases with the reduction of pressure, as supported by the dimensionless analysis. The flame puffing amplitude increases under low pressure, resulting in a portion of the flame being quenched. A special phenomenon was observed from the flame videos in that flame rotation emerged at the ending burning stage, which was attributed to the Coriolis force effect.