Acoustic radiation from subsonic and supersonic mixing layers with nonlinear PSE

Abstract

Nonlinear PSE is used to calculate the near-field hydrodynamics and far-field acoustic noise of two compressible mixing layers: a supersonic/supersonic mixing layer with a fundamental mode convection Mach number Mph = 2.0, and a subsonic mixing layer with Mph = 0.37. When compared to DNS calculations, we find that PSE accurately calculates both the near-field dynamics and the far-field acoustics for the supersonic mixing layer. For the subsonic mixing layer, PSE captures the large-scale hydrodynamic structures present in the near-field but vastly underestimates the acoustic noise in the far-field. After applying Lilley's acoustic analogy with a parallel flow assumption to construct source terms and compute the far-field acoustic radiation, we find much better agreement with the DNS results.