Sources of high-speed jet noise: Analysis of LES data and modeling

Abstract

Results from recent LES studies of high-speed jet flows and its near and far-field noise (Mendez et al. AIAA2010-271) are reviewed with an emphasis on validation of the LES results. Far-field noise is predicted using data collected on a conical FW-H surface. Very good agreement with the measurement reported by Bridges & Wernet (AIAA-2008-2834) is observed. Data analysis of the flow disturbances within the jet and in the near-field is used to better characterize the sound source processes. We analyze LES data of Bodony and Lele (Phys. Fluids, vol. 46, 2005) using a filter in the wavenumber-frequency domain. The supersonic components of pressure and radial velocity fluctuation show peaks within the jet and show the Uj8 scaling behavior consistent with the far-field radiated j noise levels. The observed scaling is also consistent with a perturbation expansion of nearly incompressible turbulent fluctuations within the jet flow. Linear global mode analysis of the non-parallel jet mean flow is performed. Features of Mach wave radiation are evident in the global modes for supersonic convection. Large transient growth is found due to convective non-normality. Some implications of this analysis for jet noise modeling are discussed.