Archive for month: July, 2016

Jet Noise Models: LES is more

Source: Cascade Technologies

Diving deeper into the research done last year on jet simulations our own Guillaume Brès has been collaborating with several academic researchers to generate extensive Large Eddy Simulation (LES) databases from subsonic jets. Together with the Institut PPRIME (France), the California Institute of Technology (USA), the Instituto Technológico de Aeronáutica (Brazil) and Stanford University (USA), the team focused specifically on isothermal Mach 0.9 turbulent jets and the resulting LES numerical data was thoroughly validated against experimental measurements in terms of flow field and radiated noise (see figure below).

Comparison of noise spectra from experimental (o) and LES cases (–––) and (—-)

The resulting LES databases are being postprocessed and mined extensively to improve understanding and modeling of jet-noise source mechanisms, and this collaborative effort has been gathering attention in the aeroacoustic community. In particular, each year, the magazine Aerospace America, the membership publication of the American Institute of Aeronautics and Astronautics (AIAA) runs a special edition describing the most ground-breaking developments in the space and aviation fields. For its 2015 issue, the AIAA’s Aeroacoustics Technical Committee named this specific research as one of the highlighted advances in aerospace sciences and aeroacoustics.

Above is the “Flying Quiet” article by Dennis McLaughlin and Anthony Pilon from the 2015 Year-in-Review magazine by the American Institute of Aeronautics and Astronautics.”

This research was recently presented at the 22^nd AIAA/CEAS Aeroacoustics Conference in Lyon, France in May 2016 [1]. The LES databases also served as the foundation for six other papers including Aaron Towne’s study [2] on “Trapped acoustic waves in the potential core of subsonic jets” which won the Best Student Paper Award at the AIAA conference. The conference papers focused on a range of topics including wavepacket models [3], reduced-order modeling [4], global modes analysis [5], and experimental measurements [6, 7].

The LES studies are supported by the NAVAIR SBIR project entitled “Modeling of interior nozzle flows and jet plumes using Large Eddy Simulations” (N68335-14-C-0047; N68335-16-C-0063), under the guidance of Dr. John T. Spyropoulos. The main LES calculations are carried out on CRAY XE6 machines at the DoD HPC facilities in ERDC DSRC.

References:

[1] Large eddy simulation for jet noise: azimuthal decomposition and intermittency of the radiated sound
G. Brès, V. Jaunet, M. Rallic, P. Jordan, A. Towne, O. Schmidt, T. Colonius, A. Cavalieri, S. Lele
AIAA paper AIAA-2016-3050, 2016

[2] Trapped acoustic waves in the potential core of subsonic jets
A. Towne, A. Cavalieri, P. Jordan, T. Colonius, V. Jaunet, O. Schmidt, G. Brès
AIAA paper AIAA-2016-2809, 2016

[3] High-frequency wavepackets in turbulent jets
A. Cavalieri, K. Sasaki, O. Schmidt, T. Colonius, P. Jordan, G. Brès
AIAA paper AIAA-2016-3056, 2016

[4] On removing the near-field coherent structures in a jet and its impact on the radiated sound
Z. Fu, A. Agarwal, A. Cavalieri, P. Jordan, G. Brès
AIAA paper AIAA-2016-2865, 2016

[5] Super- and multi-directive acoustic radiation by linear global modes of a turbulent jet
O. Schmidt, A. Towne, T. Colonius, P. Jordan, V. Jaunet, A. Cavalieri, G. Brès
AIAA paper AIAA-2016-2808, 2016

[6] Tonal dynamics and sound in free and installed turbulent jets
V. Jaunet, P. Jordan, A. Cavalieri, A. Towne, T. Colonius, O. Schmidt, G. Brès
AIAA paper AIAA-2016-3016, 2016

[7] Effects of coherence on jet-surface interaction noise
F. da Silva, C. Deschamps, P. Jordan, S. Piantanida, A. Cavalieri, G. Brès
AIAA paper AIAA-2016-2860, 2016