Three dimensional structure in a supersonic jet - Behavior near centerline

Abstract

The unsteady structure of a SUJX7SOOic jet is highly three dimensional, though the mean flow is axisymmetric.In simulating a circular jet. the centaline ~lS a computaliooaJ boundary.As such.spurious modes can be generaled near centerline, unless special attention is given to the behavior of the 3D structure near the centerline.Impuper treatment of the dependent variables near the centecline results in the solution diverging or being suitable only f<r small amplitude excitation.With a careful tteattnen1 of the centerline foonulatioo, no spurious mode is generated.The resullS show that a near linear disturbance growth is obtained, ~ the linear stability theory indicates.At high levels of excitation, nonlinear development of disturbances is evident and saturation is reached downstream.