Nozzle geometry effects on supersonic jet interaction

In this paper, we present observations on the impact of mechanical chevrons on modifying the flow field and noise emanated by supersonic jet flows. These observations are derived from both a monotonically integrated large-eddy simulation (MILES) approach to simulate the near fields of supersonic jet flows and laboratory experiments. The nozzle geometries used in this research are representative of practical engine nozzles. A finite-element flow solver using unstructured grids allows us to model the nozzle geometry accurately and the MILES approach directly computes the large-scale turbulent flow structures. The emphasis of the work is on “off-design” or non-ideally expanded flow conditions. LES for several total pressure ratios under non-ideally expanded flow conditions were simulated and compared to experimental data. The agreement between the predictions and the measurements on the flow field and near-field acoustics is good. After this initial step on validating the computational methodology, the impact of mechanical chevrons on modifying the flow field and hence the near-field acoustics is being investigated. This paper presents the results to date and further details will be presented at the meeting.

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Analysis of nozzle geometry effect on supersonic jet noise using Schlieren

The Journal of the Acoustical Society of America ◽

10.1121/1.4969449 ◽

2016 ◽

Vol 140 (4) ◽

pp. 3043-3043

Author(s):

Yuta Ozawa ◽

Akira Oyama ◽

Masayuki Anyoji ◽

Akira Oyama ◽

Hiroya Mamori ◽

...

Keyword(s):

Supersonic Jet ◽

Jet Noise ◽

Nozzle Geometry ◽

Geometry Effect ◽

Supersonic Jet Noise

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Supersonic Jet Noise Reduction Technologies for Gas Turbine Engines

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4002914 ◽

2011 ◽

Vol 133 (10) ◽

Cited By ~ 11

Author(s):

David Munday ◽

Nick Heeb ◽

Ephraim Gutmark ◽

Junhui Liu ◽

K. Kailasanath

Keyword(s):

Flow Field ◽

Near Field ◽

Supersonic Jet ◽

Acoustic Emissions ◽

Nozzle Geometry ◽

Axial Position ◽

Eddy Simulation ◽

Image Velocimetry ◽

Large Eddy ◽

The Impact

This paper presents observations and simulations of the impact of several technologies on modifying the flow-field and acoustic emissions from supersonic jets from nozzles typical of those used on military aircraft. The flow-field is measured experimentally by shadowgraph and particle image velocimetry. The acoustics are characterized by near- and far-field microphone measurements. The flow- and near-field pressures are simulated by a monotonically integrated large eddy simulation. Use of unstructured grids allows accurate modeling of the nozzle geometry. The emphasis of the work is on “off-design” or nonideally expanded flow conditions. The technologies applied to these nozzles include chevrons, fluidic injection, and fluidically enhanced chevrons. The fluidic injection geometry and the fluidic enhancement geometry follow the approach found successful for subsonic jets by employing jets pitched 60 deg into the flow, impinging on the shear layer just past the tips of the chevrons or in the same axial position when injection is without chevrons.

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