Introduction to the special issue on supersonic jet noise.

This editorial's goals are (1) to highlight a few key developments in supersonic jet and launch vehicle noise research over the past several decades while describing some of the critical modern requirements facing government and industry organizations and (2) to summarize the contributions of the articles in this Supersonic Jet Noise special issue in the context of these developments and requirements.

Steady active control of noise radiation from highly heated supersonic jets.

The goal of the present investigation is to study the effect of using fluid inserts for noise control at high exhaust temperatures by performing a sequence of large eddy simulations on a typical military-style nozzle, both with and without fluid inserts, at jet inlet total temperature ratios of 2.5, 5, and 7. An exact physics-based splitting of the jet flow-field into its hydrodynamic, acoustic, and thermal components reveals clear evidence of a reduction in the radiation efficiency of Mach waves from the controlled jet.

A three dimensional parabolic equation method for sound propagation in moving inhomogeneous media.

In this paper, a formulation of the Helmholtz equation for three dimensional sound propagation in a moving inhomogeneous medium in cylindrical coordinates is derived. Based on this formulation, a three dimensional parabolic equation (PE) is constructed. This PE can be used to model sound propagation in an inhomogeneous arbitrary moving medium.