Results from recent LES studies of high-speed jet flows and its near and far-field noise (Mendez et al. AIAA-2010-271) 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 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.
Bibliographical noteFunding Information:
This research was supported by the Supersonics element of NASA Fundamental Aeronautics Program under grant number NNX07AC94A and in part by the Boeing Company. We appreciate technical interactions with Dr. James Bridges and his generous help with the jet noise data. We are also grateful to Prof. Daniel J. Bodony for sharing his jet LES database for analysis by Jaiyoung Ryu in his thesis.
- Global modes
- Jet aeroacoustics
- Jet noise
- Large-eddy simulation
- Noise sources