Effects of ambient turbulence and fuel properties on the evaporation rate of single droplets

Results of the evaporation of a single liquid fuel droplet in various free-stream turbulence intensities and scales are reported. Experiments are carried out at room temperature by using n-heptane and n-decane fuels at Red=100. A low-speed vertical wind tunnel with different turbulence intensities and scales, controlled by using different sizes of disk, is constructed. The free-stream turbulence intensities are varied in the range from 1% to 60% and the integral length scales are from 2.5 to 20 times of the initial droplet diameter. Results show that the time history of droplet diameter follows the d2-law in turbulent environments with generally higher evaporation rates as compared with those in quasi-laminar cases. Combined effects of liquid fuel properties and ambient turbulence properties on the evaporation rate can be reasonably well explained by the correlation of normalized evaporation rate with the effective vaporization Damköhler number, Dav.