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@ARTICLE{Cetin:858011,
author = {Cetin, Mehmet Onur and Koh, Seong Ryong and Meinke,
Matthias and Schröder, Wolfgang},
title = {{C}omputational analysis of exit conditions on the sound
field of turbulent hot jets},
journal = {Comptes rendus mécanique},
volume = {346},
number = {10},
issn = {1631-0721},
address = {Paris},
publisher = {Elsevier},
reportid = {FZJ-2018-06955},
pages = {932 - 947},
year = {2018},
abstract = {A hybrid computational fluid dynamics (CFD) and
computational aeroacoustics (CAA) method is used to compute
the acoustic field of turbulent hot jets at a Reynolds
number and a Mach number . The flow field computations are
performed by highly resolved large-eddy simulations (LES),
from which sound source terms are extracted to compute the
acoustic field by solving the acoustic perturbation
equations (APE). Two jets are considered to analyze the
impact of exit conditions on the resulting jet sound field.
First, a jet emanating from a fully resolved non-generic
nozzle is simulated by solving the discrete conservation
equations. This computation of the jet flow is denoted
free-exit-flow (FEF) formulation. For the second
computation, the nozzle geometry is not included in the
computational domain. Time averaged exit conditions, i.e.
velocity and density profiles of the first formulation, plus
a jet forcing in form of vortex rings are imposed at the
inlet of the second jet configuration. This formulation is
denoted imposed-exit-flow (IEF) formulation. The
free-exit-flow case shows up to $50\%$ higher turbulent
kinetic energy than the imposed-exit-flow case in the jet
near field, which drastically impacts noise generation. The
FEF and IEF configurations reveal quite a different
qualitative behavior of the sound spectra, especially in the
sideline direction where the entropy source term dominates
sound generation. This difference occurs since the noise
sources generated by density and pressure fluctuations are
not perfectly modeled by the vortex ring forcing method in
the IEF solution. However, the total overall sound pressure
level shows the same qualitative behavior for the FEF and
IEF formulations. Towards the downstream direction, the
sound spectra of the FEF and IEF solutions converge.},
ddc = {530},
pnm = {899 - ohne Topic (POF3-899)},
pid = {G:(DE-HGF)POF3-899},
typ = {PUB:(DE-HGF)16},
doi = {10.1016/j.crme.2018.07.006},
url = {https://juser.fz-juelich.de/record/858011},
}