Computational fluid dynamics (CFD) was used to evaluate the flow field and thrust performance of a promising concept for reducing the noise at take-off of dual-stream turbofan nozzles. The concept, offset stream technology, reduces the jet noise observed on the ground by diverting (offsetting) a portion of the fan flow below the core flow, thickening and lengthening this layer between the high-velocity core flow and the ground observers. In this study a wedge placed in the internal fan stream is used as the diverter. Wind, a Reynolds averaged Navier–Stokes (RANS) code, was used to analyze the flow field of the exhaust plume and to calculate nozzle performance. Results showed that the wedge diverts all of the fan flow to the lower side of the nozzle, and the turbulent kinetic energy on the observer side of the nozzle is reduced. This reduction in turbulent kinetic energy should correspond to a reduction in noise. However, because all of the fan flow is diverted, the upper portion of the core flow is exposed to the freestream, and the turbulent kinetic energy on the upper side of the nozzle is increased, creating an unintended noise source. The blockage due to the wedge reduces the fan mass flow proportional to its blockage, and the overall thrust is consequently reduced. The CFD predictions are in very good agreement with experimental flow field data, demonstrating that RANS CFD can accurately predict the velocity and turbulent kinetic energy fields. While this initial design of a large scale wedge nozzle did not meet noise reduction or thrust goals, this study identified areas for improvement and demonstrated that RANS CFD can be used to improve the concept.

1.
Papamoschou
,
D.
, 2002, “
Noise Suppression in Moderate-Speed Multistream Jets
,” AIAA Paper No. 2002-2557.
2.
Papamoschou
,
D.
, 2004, “
New Method for Jet Noise Reduction in Turbofan Engines
,”
AIAA J.
,
42
(
11
), pp.
2245
2253
. 0001-1452
3.
Papamoschou
,
D.
, and
Nishi
,
K.
, 2005, “
Jet Noise Suppression With Fan Flow Deflectors in Realistic-Shaped Nozzle
,” AIAA Paper No. 2005-993.
4.
Castner
,
R.
, 1994, “
The Nozzle Acoustic Test Rig; An Acoustic and Aerodynamic Free-Jet Facility
,”
NASA
Report No. TM 106495.
5.
Dippold
,
V.
,
Foster
,
L.
, and
Wiese
,
M.
, 2007, “
Computational Analyses of Offset Stream Nozzles for Noise Reduction
,” AIAA Paper No. 2007-3589.
6.
Brown
,
C.
,
Bridges
,
J.
, and
Henderson
,
B.
, 2007, “
Offset Stream Technology Test—Summary of Results
,” AIAA Paper No. 2007-3664.
7.
Zaman
,
K.
,
Bridges
,
J.
, and
Papamoschou
,
D.
, 2007, “
Offset Stream Technology—Comparison of Results From UC and GRC Experiments
,” AIAA Paper No. 2007-438.
8.
Henderson
,
B.
,
Norum
,
T.
, and
Bridges
,
J.
, 2006, “
An MDOE Assessment of Nozzle Vanes for High Bypass Ratio Jet Noise Reduction
,” AIAA Paper No. 2006-2543.
9.
Papamoschou
,
D.
,
Vu
,
A.
, and
Johnson
,
A.
, 2006, “
Aerodynamics of Wedge-Shaped Deflectors for Jet Noise Reduction
,” AIAA Paper No. 2006-3655.
10.
Janardan
,
B. A.
,
Hoff
,
G. E.
,
Barter
,
J. W.
,
Martens
,
S.
,
Gliebe
,
P. R.
,
Mengle
,
V.
, and
Dalton
,
W. N.
, 2000, “
AST Critical Propulsion and Noise Reduction Technologies for Future Commercial Subsonic Engines Separate-Flow Exhaust System Noise Reduction Concept Evaluation
,”
NASA
Report No. CR 2000-210039.
13.
Menter
,
F. R.
, 1994, “
Two-Equation Eddy-Viscosity Turbulence Models for Engineering Applications
,”
AIAA J.
0001-1452,
32
(
8
), pp.
1598
1605
.
14.
Papamoschou
,
D.
, 2003, “
A New Method for Jet Noise Reduction in Turbofan Engines
,” AIAA Paper No. 2003-1059.
15.
Khavaran
,
A.
, and
Kenzakowski
,
D. C.
, 2007, “
Noise Generation in Hot Jets
,”
NASA
Report No. CR 2007-214924.
16.
Papamoschou
,
D.
, 2006, “
Fan Flow Deflection in Simulated Turbofan Exhaust
,”
AIAA J.
,
44
(
12
), pp.
3088
3097
. 0001-1452
17.
DeBonis
,
J.
, 2008, “
RANS Analyses of Turbofan Nozzles With Wedge Deflectors for Noise Reduction
,” AIAA Paper No. 2008-0041.
18.
Wernet
,
M.
, and
Bridges
,
J.
, 2002, “
Application of DPIV to Enhanced Mixing Heated Nozzle Flows
,” AIAA Paper No. 2002-0691.
19.
Dembowski
,
M. A.
, and
Georgiadis
,
N. J.
, 2002, “
An Evaluation of Parameters Influencing Jet Mixing Using the WIND Navier-Stokes Code
,”
NASA
Report No. TM 2002-211727.
20.
Georgiadis
,
N. J.
, and
DeBonis
,
J. R.
, 2006, “
Navier-Stokes Analysis Methods for Turbulent Jet Flows With Application to Aircraft Exhaust Nozzles
,”
Prog. Aerosp. Sci.
,
42
, pp.
377
418
. 0376-0421
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