Nonparallel Effects on the Stability of Jet Flows

Abstract

A theoretical analysis of the linear, spatial stability of Bickley’s jet is presented. The analysis takes into account the effects of transverse velocity component and the axial variations of the basic flow and of the disturbance amplitude, wavenumber and spatial growth rate. The integration of stability equations is started from the outer region of the jet toward the jet axis using the solution of the asymptotic forms of the governing equations. Results are compared with those for the parallel-flow stability analysis. It is found that the nonparallel effects decrease the wave number at low frequencies but increase it at high frequencies. Thus the nonparallel effects make Bickley’s jet unstable over a wider frequency range.