I. Interference During Burning of Body-Centered Cubic Arrays of Nine Fuel Droplets in Air. II. Spray Formation and Evaporation

Citation

Kanevsky, Joseph Norman (1956) I. Interference During Burning of Body-Centered Cubic Arrays of Nine Fuel Droplets in Air. II. Spray Formation and Evaporation. Engineer's thesis, California Institute of Technology. doi:10.7907/JHWV-HB29. https://resolver.caltech.edu/CaltechETD:etd-03252004-094228

Abstract

In order to gain some understanding of interference effects during the combustion and evaporation of fuel sprays, simple three-dimensional body-centered cubic arrays of nine n-heptane or nine methyl alcohol droplets burning in air have been studied. Different cube sizes were used to vary the amount of interference obtained during combustion of the droplets. Photographic studies of the center droplet in this nine-droplet array were made in order to determine the qualitative effects of droplet spacing on the evaporation constant (K') while combustion was in progress and to determine whether the mass rate of burning was proportional to the first power of droplet diameter for a three-dimensional array of droplets. Experimental results indicate that, when the droplets are in close proximity and the flames completely merged, the evaporation constant is reduced by 40 percent below the value obtained for minimum interference. A 25 percent increase in the evaporation constant over single-droplet values for K' was noted when the droplet spacing was altered to reduce local heat losses from the flame fronts. The results obtained from studies of the center droplet substantiate Probert's assumption (Ref. 38) that the square of droplet diameter decreases linearly with time. Unsuccessful attempts to study the combustion of liquid bipropellant mixtures and to examine the "burning" of red fuming nitric acid in an ammonia atmosphere are described. In Part II, a general discussion of information available on the disintegration of liquid jets, spray characteristics, mean droplet size, droplet-size distribution, and spray evaporation is presented. The use of similarity considerations in analyzing spray-nozzle performance is demonstrated. Calculation of K' for a spray from experimental spray evaporation data is described and the results of these calculations tabulated.

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