M. Salikuddin, S. Martens, H. Shin, and R.K. Majjigi

General Electric Aircraft Engines Company, Cincinnati, Ohio

Acoustic and Laser Doppler Anemometer

Results for Confluent, 22-Lobed, and

Unique-Lobed Mixer Exhaust Systems

for Subsonic Jet Noise Reduction

NASA/CR—2002-211598

September 2002
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M. Salikuddin, S. Martens, H. Shin, and R.K. Majjigi

General Electric Aircraft Engines Company, Cincinnati, Ohio

Acoustic and Laser Doppler Anemometer

Results for Confluent, 22-Lobed, and

Unique-Lobed Mixer Exhaust Systems

for Subsonic Jet Noise Reduction

NASA/CR—2002-211598

September 2002

National Aeronautics and

Space Administration

Glenn Research Center

Prepared under Contract NAS3–26617
Acknowledgments

This report is prepared by GE Aircraft Engines, Cincinnati, Ohio for NASA Glenn Research Center, Cleveland, Ohio

under LET Contract NAS3–26617, Task Order 31. Mr. Gene Krejsa was the Project Manager for NASA Glenn

Research Center and Dr. R.K. Majjigi was the Project Manager for GEAE. The authors are thankful to Mr. J. Brausch

and Mr. R.R. Babbitt for their contributions in designing and acquiring the model hardware and helping the

installation of the hardware in GEAE’s Cell 41 for testing. The authors are also thankful to Mr. J. Hencheck and

Ms. S. Thomson for running the test facility, and to Dr. K. Kinzie for helping in data analysis. The authors are

particularly thankful to Dr. B.A. Janardan for his useful suggestions and discussions during the course of this work.

Available from

NASA Center for Aerospace Information

7121 Standard Drive

Hanover, MD 21076

National Technical Information Service

5285 Port Royal Road

Springfield, VA 22100

Trade names or manufacturers’ names are used in this report for

identification only. This usage does not constitute an official

endorsement, either expressed or implied, by the National

Aeronautics and Space Administration.

Available electronically at http://gltrs.grc.nasa.gov
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September 2002

NASA CR—2002-211598

E–13385

WU–781–30–12–00

NAS3–26617

201

Acoustic and Laser Doppler Anemometer Results for Confluent, 22-Lobed, and

Unique-Lobed Mixer Exhaust Systems for Subsonic Jet Noise Reduction

M. Salikuddin, S. Martens, H. Shin, and R.K. Majjigi

Acoustic measurement; Laser doppler velocimeters; Noise prediction; Noise reduction;

Scale models; Exhaust systems; Subsonic flow; Aeroacoustics; Jet aircraft noise

Unclassified -Unlimited

Subject Categories: 07 and 34 Distribution: Nonstandard

General Electric Aircraft Engines Company

Mail Drop A411

One Neumann Way

Cincinnati, Ohio

Project Manager, James Bridges, Structures and Acoustics Division, NASA Glenn Research Center, organization

code 5940, 216–433–2693.

The objective of this task was to develop a design methodology and noise reduction concepts for high bypass exhaust

systems which could be applied to both existing production and new advanced engine designs. Special emphasis was

given to engine cycles with bypass ratios in the range of 4:1 to 7:1, where jet mixing noise was a primary noise source at

full power takeoff conditions. The goal of this effort was to develop the design methodology for mixed-flow exhaust

systems and other novel noise reduction concepts that would yield 3 EPNdB noise reduction relative to 1992 baseline

technology. Two multi-lobed mixers, a 22-lobed axisymmetric and a 21-lobed with a unique lobe, were designed. These

mixers along with a confluent mixer were tested with several fan nozzles of different lengths with and without acoustic

treatment in GEAE’s Cell 41 under the current subtask (Subtask C). In addition to the acoustic and LDA tests for the

model mixer exhaust systems, a semi-empirical noise prediction method for mixer exhaust system is developed. Effort

was also made to implement flowfield data for noise prediction by utilizing MGB code. In general, this study established

an aero and acoustic diagnostic database to calibrate and refine current aero and acoustic prediction tools.