Evaporation and Combustion of a Fuel Drop in Supercritical Environments. 3rd Report, Observation from the Lateral Side of a Drop on a Hot Wall.

Abstract

Evaporation and combustion processes of a single fuel drop in ambient gas pressurized and heated beyond the critical point of the fuel (a supercritical environment) were observed from the lateral side of the drop on a flat hot wall settled in a high-pressure bomb. The ambient gas temperature near the wall was controlled to be the same as the wall temperature. The fuel drop showed different evaporation lifetimes in air and in nitrogen. The difference in the evaporation lifetime was larger under higher ambient pressure. Drop volume decreased gradually in a subcritical environment, but in a supercritical environment the drop maintained close to the initial volume during evaporation and showed a sudden decrease just before extinction. In an ambient temperature range around the critical tempreature of the fuel, longer duration of combustion and smaller flame width were found for the drop in the supercritical ambient pressure than for that in the subcritical ambient pressure.