Christopher E. Hughes, Robert J. Jeracki, Richard P. Woodward,
and Christopher J. Miller
Glenn Research Center, Cleveland, Ohio
Fan Noise Source Diagnostic Test—Rotor
Alone Aerodynamic Performance Results
NASA/TM—2005-211681
April 2005
AIAA–2002–2426
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Fan Noise Source Diagnostic Test—Rotor
Alone Aerodynamic Performance Results
NASA/TM—2005-211681
April 2005
National Aeronautics and
Space Administration
Glenn Research Center
Prepared for the
Eighth Aeroacoustics Conference
cosponsored by the American Institute of Aeronautics and Astronautics
and the Confederation of European Aerospace Societies
Breckenridge, Colorado, June 17–19, 2002
AIAA–2002–2426
Christopher E. Hughes, Robert J. Jeracki, Richard P. Woodward,
and Christopher J. Miller
Glenn Research Center, Cleveland, Ohio
Acknowledgments
Acknowledgment is given to General Electric Aircraft Engines for designing the R4 model fan and providing it to
NASA as the current technology high bypass fan baseline for this test. Also, GEAE designed and fabricated the
three model OGV configurations and model nacelle used in this test under NASA Contract NAS3–26617,
Task Order 63 and NAS3–98004, Task Order 7. Acknowledgment is also given to the Boeing Aircraft
Company for their earlier fan noise research with and without the presence of downstream
stators. Those Boeing results provided insight and focus for the current
NASA rotor alone noise research program.
Available from
NASA Center for Aerospace Information
7121 Standard Drive
Hanover, MD 21076
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22100
Available electronically at http://gltrs.grc.nasa.gov/GLTRS
NASA/TM—2005-211681
1
Fan Noise Source Diagnostic Test—Rotor Alone
Aerodynamic Performance Results
Christopher E. Hughes, Robert J. Jeracki,
Richard P. Woodward, and Christopher J. Miller
National Aeronautics and Space Administration
Glenn Research Center
Cleveland, Ohio 44135
Abstract
The aerodynamic performance of an isolated
fan, or rotor alone, model was measured in the
NASA Glenn Research Center 9- by 15-Foot Low
Speed Wind Tunnel as part of the Fan
Broadband Source Diagnostic Test conducted at
NASA Glenn. The Source Diagnostic Test was
conducted to identify the noise sources within a
wind tunnel scale model of a turbofan engine and
quantify their contribution to the overall system
noise level. The fan was part of a 1/5th scale
model representation of the bypass stage of a
current technology turbofan engine. For the rotor
alone testing, the fan and nacelle, including the
inlet, external cowl and fixed area fan exit nozzle,
were modeled in the test hardware; the internal
outlet guide vanes located behind the fan were
removed. Without the outlet guide vanes, the
velocity at the nozzle exit changes significantly,
thereby affecting the fan performance. As part of
the investigation, variations in the fan nozzle area
were tested in order to match as closely as
possible the rotor alone performance with the fan
performance obtained with the outlet guide vanes
installed. The fan operating performance was
determined using fixed pressure/temperature
combination rakes and the corrected weight flow.
The performance results indicate that a suitable
nozzle exit was achieved to be able to closely
match the rotor alone and fan/outlet guide vane
configuration performance on the sea level
operating line. A small shift in the slope of the sea
level operating line was measured, which
resulted in a slightly higher rotor alone fan
pressure ratio at take-off conditions, matched fan
performance at cutback conditions, and a slightly
lower rotor alone fan pressure ratio at approach
conditions. However, the small differences in fan
performance at all fan conditions were
considered too small to affect the fan acoustic
performance.
Introduction
Recent aircraft engine noise research by NASA
and the aerospace industry
1-5
has focused on
identifying the composition of the noise sources in a
modern turbofan aircraft engine, their generation
mechanisms, and the level of contribution to the
total aircraft system noise level. A test was
conducted in the NASA Glenn Research Center 9-
by 15-Foot Low Speed Wind Tunnel (9x15 LSWT),
called the Source Diagnostic Test. The objectives
of the test were to investigate the aerodynamic and
acoustic performance of the bypass stage portion
of a scale model high bypass ratio turbofan engine
and three Outlet Guide Vane (OGV) configurations
that were designed to reduce turbofan noise. The
turbofan model design was representative of a
current technology high bypass turbofan engine in
service today. As part of this test, detailed acoustic
and aerodynamic flowfield surveys were conducted
using a variety of research techniques.
One of the
techniques used to determine the fan only
component of the system noise was eliminating the
rotor/stator interaction by removing the OGVs.
Since the OGVs are the structural supporting
component for the model nacelle, an externally
supported nacelle was used during testing.
However, without the OGVs, the swirl component of
the bypass nozzle exit flow was not removed,
resulting in a higher fan exit velocity and lower fan
exit pressure. Therefore, the fan nozzle exit area
needed to be modified to produce the same fan
operating conditions compared to a fan with OGVs
installed at the same fan speed. This paper
presents the process used in determining the
correct nozzle exit area for the rotor alone nacelle,
and compares the fan aerodynamic performance
obtained without OGVs, or rotor alone
performance, to the fan performance obtained with
OGVs installed.
