Prediction of Spray Breakup Specifications by Investigation of Nonlinear Spray Instability Growth

In this study a nonlinear asymmetric instability analysis carried out to study primary atomization of annular liquid sheets emanating from the prefilming airblast atomizer using a perturbation method and potential flow assumption. In this direction، firstly governing equations derived according to potential flow assumption and conservation equations while dynamic and static boundary condition at the interface are considered. The first and second order equation is solved using Mathematica. In order to evaluate the results، model results in 2D geometry compared with results of Jazayeri 2D sheet instability analysis. Then the variation of deduced instability growth rate against wave number، compared with the results of other researchers. At next step an experimental test performed to measure of primary breakup length of an airblast atomizer and the result compared with the primary breakup length which deduced from nonlinear and linear instability analysis. Finally the primary breakup length of nonlinear study compared with a curve، which fitted on experimental results at various we number.