ESTIMATION OF THE BREAKUP LENGTH FOR THE ANNULAR AND THE ROUND LIQUID JET USING LINEAR INSTABILITY ANALYSIS

Abstract

A linear instability analysis of an inviscid annular liquid sheet emanating from anatomizer subjected to inner and outer swirling air streams and a non-swirl round liquid jet has beencarried out. The dimensionless dispersion equation that governs the instability was derived andwas solved by Numerical method to investigate the effects of the liquid-gas swirl orientation onthe maximum growth rate and its corresponding unstable wave number that produces the finestdroplets. To understand the effect of air swirl orientation with respect to liquid swirl direction, fourpossible combinations with both swirling air streams with respect to the liquid swirl direction havebeen considered. Results show that at low liquid swirl Weber number a combination of co-innerair stream and counter-outer air stream has the largest most unstable wave number and shortestbreakup length. The combination of inner and the outer air stream co-rotating with the liquid hasthe highest growth rate. Also, the results for round liquid jet and planar liquid sheet show that thelinear theory accurately predicts the variation in breakup length with jet velocity.