Acoustic field associated with parabolized stability equation models in turbulent jets

Abstract

Wavepackets are large-scale turbulent structures that are correlated and advected over distances that are large compared to the integral scales of turbulence, and have been shown to be responsible for the peak noise radiated at aft angles to the jet axis. The present paper discusses linear models of these wavepackets for supersonic turbulent jets based on Parabolized Stability Equations (PSE). In the past, results of this approach were shown to be in excellent agreement with coherent structures extracted from experimental near-field pressure and velocity data in subsonic jets. Here, we make use of a Large Eddy Simulation (LES) database for an isothermal and a moderately heated Mach 1.5 turbulent jets. Careful comparisons of the PSE models with near-field pressure fields from LES, filtered by means of Proper Orthogonal Decomposition (POD), demonstrate acceptable fidelity of the model. Finally, the acoustic far-field associated with the PSE wavepackets is computed using a Kirchho surface method, capturing reasonably well the far-field pressure at angles close to the peak.