Further investigations of combustion of free droplets in a freely falling chamber including moving droplets

For the further investigation of the combustion of free droplets under a zero-gravity condition in a freely falling chamber, the experimental apparatus and technique were improved as follows: Increased duration of zero-gravity condition; observation of moving droplets as well as stationary droplets; and schlieren system to observe the hot gas zone. In addition to n -heptane, ethyl alcohol and benzene were also used as fuels. The effects of the initial droplet diameter on the evaporation constant and the variation of the flame/droplet diameter ratio were found to be completely consistent with predictions based on the authors' previous experiment. The influence of the relative velocity of moving droplets on their combustion characteristics such as the evaporation constant, flame shape and behavior of the hot gas zone were investigated, and the combustion of fuel droplets in weak forced convection, not disturbed by natural convection, has been studied for the first time.