Combustion characteristics of n-heptane at high altitudes

Presented in this paper is part of an experimental series conducted at different altitudes to investigate the influence of ambient pressure on buoyancy driven diffusion combustion of a liquid fuel. A set of n-heptane pool fire experiments were conducted at two geographic locations on the Tibetan plateau with altitudes greater than 3600 m. In addition to the measurements of fuel mass loss, flame temperature and irradiance, transmittance through smoke and flame height were also measured. The experimental results confirm the findings of previous studies at relatively lower altitudes and show that the burning rate per unit area, radiation heat flux and average flame axis temperature decrease when the altitude is increased. Direct evidence was also obtained to show that the radial average extinction coefficient at a given height above the fuel surface is inversely proportional to the altitude. A preliminary discussion is made on the mechanism of pressure influence on buoyancy driven fire behavior.