Experimental and calculated histories of vaporizing fuel drops

R. J. Priem, G. L. Borman, M. M. El Wakil, O. A. Uyehara, P. S. Myers
Aug 1957

The present report contains the results of an experimental and theoretical investigation of the vaporization of fuel droplets in heated air under atmospheric pressure. First, an experimental investigation of the temperature and mass histories of single droplets was made, with emphasis on small drops down to 500 microns. Second, a comparison of experimental histories with calculated temperature and mass histories was made. In connection with the calculated histories, the equations of change and the associated boundary conditions are given in reduced form along with the various dimensionless parameters that would appear in a solution of these equations. Third, the time taken by a droplet vaporizing in high-temperature air to form a mixture of fuel vapor and air of combustible strength in the film of the droplet and at the self-ignition temperature is calculated. The concept of physical ignition delay of single droplets is thus presented. In addition, the vaporization of fuel droplets in a spray under conditions where there exists an influence of one droplet on another is theoretically investigated.

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