Ignition of blended-fuel droplet in high-temperature atmosphere

Abstract

Ignition time of a suspended fuel droplet is obtained experimentally with high ambient temperature. A stationary fuel droplet suspended by a fine silica fiber is taken into a furnace moving on rail and is quickly exposed to high ambient temperature. Blended fuels of n-heptane and n-hexadecane are used, and the effects of fuel mixture ratio, initial droplet diameter, and ambient air temperature on ignition time are observed. For pure hexadecane droplets, ignition time increases with the increase in initial droplet diameter. On the other hand, it decreases for pure heptane, especially under lower ambient temperatures. For the case of mixed fuel, the variation of ignition time with the initial droplet diameter has a characteristic feature, namely the results show that an initial droplet diameter exists at which the ignition time has the maximum value and that this diameter increases with a decrease of the heptane concentration or the ambient temperature. The maximum ignition time is also confirmed by the combination of ethylalcohol and decylalcohol.