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High resolution simulations of high Reynolds number jets with microjet injection

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conference contribution
posted on 2016-09-20, 11:07 authored by M.E. Rife, Gary PageGary Page
Large eddy simulations have been performed of a Mach 0.9 jet at a Reynolds number of 1.3 million for both a clean and microjet injected configurations. Two numerical grids were used for the simulations differing in the number of azimuthal cells. The first with 720 cells and an azimuthal clustering near the microjet injection locations, and the other with 1440 cells and a uniform azimuthal cell spacing that matches the finest cell for the clustered case. The grids contained 100 million and 200 million cells respectively. A standard Smagorinsky sub-grid scale model was used together with a synthetic trip in the nozzle shear layer. The non-uniform grid with 720 cells azimuthally showed a variation in laminar to turbulent transition location that was a function of the clustering, with later transition in the coarser regions. However, this had little detrimental impact on mean velocity distributions further downstream. The results of the simulations were compared with PIV experimental data and good agreement of mean radial velocity and turbulent kinetic energy profiles were obtained. The microjets caused a deformation of the shear layer, reducing the radial location of peak turbulence kinetic energy in-line with the microjets. Additionally, the shear layer is translated away from the jet centreline between the microjets and becomes flat in the regions between the microjets. A Ffowcs Williams-Hawking technique was used to propagate the unsteady pressure fluctuations to the far-field. Spectral data at downstream and sideline observer locations indicated the presence of a high-frequency peak in the microjet case which is consistent with the size of the microjets. The microjets provide a blockage effect to the main jet and the peak is probably a shedding like behaviour. Overprediction of overall sound pressure levels by 6-8 dB was found when compared to the experimental data, however, the correct behaviour with observer angle was captured and more importantly the microjets showed a reduction in OASPL of around 2 dB across a range of angles, similar to the experiment results.

Funding

Computing time for these calculations was provided by the UK Turbulence Consortium under funding from the EPSRC grant EP/G069581/1.

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Aeronautical and Automotive Engineering

Published in

19th AIAA/CEAS Aeroacoustics Conference

Pages

248 - ?

Citation

RIFE, M.E. and PAGE, G.J., 2013. High resolution simulations of high Reynolds number jets with microjet injection. IN: Proceedings of the 19th AIAA/CEAS Aeroacoustics Conference, Aeroacoustics Conferences, Berlin, May 27-29th, (AIAA 2013-2263).

Publisher

Published by the American Institute of Aeronautics and Astronautics, Inc. © the author(s)

Version

  • AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2013

Notes

This conference paper was accepted for publication by AIAA and the definitive version is available at: http://dx.doi.org/10.2514/6.2013-2263

ISBN

9781624102134

Language

  • en

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