The Instability of High Speed Jets

Abstract

This paper provides a review of the stability characteristics of high speed jets. These characteristics not only play a role in the transition of jet flows to turbulence, in the traditional sense of hydrodynamic stability theory, but also are key to understanding the behavior of large scale turbulent structures in the jet. They are also an important component in understanding the noise radiation by high speed jets. The paper begins with the development of the linear stability equations and then reviews the classes of instability waves in a jet, modeled as a cylindrical vortex sheet. Finite shear layer thickness effects are then discussed. This includes a review of numerical methods for the solution of the stability equations. The effects of jet Mach number and temperature are then presented. Additional topics considered include, the effects of mean flow divergence, the effect of Reynolds number, and the effect of the jet's geometry. Finally, the nature of absolute instabilities in jet flows is described, both from an analytical viewpoint as well as applications.