Influence of downstream distance on the spray characteristics of pressure-swirl atomizers

An analytical study is made of the factors that are responsible for the observed changes in fuel spray characteristics with axial distance downstream of a pressure-swirl nozzle. To simplify the analysis the effect of fuel evaporation is neglected, but full account is taken of the effects of spray dispersion and drop acceleration (or deceleration). Equations are derived and graphs are presented to illustrate the manner and extent to which the variations of mean drop size and drop-size distribution with axial distance are governed by such factors as ambient air pressure and velocity, fuel injection pressure initial mean drop size, and initial drop-size distribution.