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Atomization and Sprays

Journal of the International Institutes for Liquid Atomization and Spray Systems

ISSN for PRINT: 1045-5110

Institutional price:	$787.00
Issues per year:	8

Best Paper Award Selection - Editorial Board Site

2004, Volume14

113 pages

Issue price - $85.00

AN ENGINEERING MODEL FOR THE FUEL SPRAY FORMATION OF DEFORMING DROPLETS

William Kvasnak
Department of Mechanical and Aeronautical Engineering, Clarkson University, Potsdam, New York, USA

Goodarz Ahmadi
Mechanical and Aeronautical Engineering Department, Clarkson University, Potsdam, NY 13699-5725, USA

David J. Schmidt
Department of Mechanical and Aeronautical Engineering, Clarkson University, Potsdam, New York, USA

ABSTRACT

A computational model for evaluating the formation of sprays from a liquid jet is developed. The dispersion of evaporating droplets in a spray in a simulated turbulent flow field is examined. A vaporization model is used for evaluating the evaporation rate of deforming ellipsoidal droplets. The instantaneous fluctuating fluid velocity and velocity gradient components at the centroid of the droplet are evaluated with the use of a probability density function (PDF)-based Langevin model. Motions of atomized fuel droplets are analyzed, and ensemble and time averaging are used for evaluating the statistical properties of the droplets. Effects of droplet deformation and breakup on the statistics of spray dispersion are studied. The trajectory statistics of evaporating and nonevaporating liquid ellipsoidal droplets are compared with those of solid particles and fluid point particles. The results show that the mean-square fluctuation velocities of the droplets vary significantly with their size and shape. Furthermore, the mean-square fluctuation velocities of the evaporating droplets differ somewhat from those of point and solid particles. Droplet turbulent diffusivities, however, are found to be close to the diffusivity of point particles. The formation of a spray in the absence of atomizing air is simulated. The model accounts for the evaporation, deformation, and breakup of liquid droplets in a turbulent spray. The droplet velocity, concentration, and size of the simulated spray are compared with the experimental data and qualitative agreement is observed.