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Aero-Acoustic Propulsion Laboratory (AAPL)
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The AAPL provides an anechoic testing environment for acoustic measurements of aeropropulsion components.


The AAPL dome at night C-1997-1769: NATR Noise Acoustic Test Rig in the APPL

The Aero-Acoustic Propulsion Laboratory (AAPL) is a world-class anechoic testing environment providing outstanding testing services in aircraft noise reduction, with an emphasis in engine nozzle and fan components.
Facility Overview
With over 15 years of testing experience in acoustic research and development, the Aero-Acoustic Propulsion Laboratory (AAPL), located at the NASA Glenn Research Center, is a world-class facility providing outstanding testing services in aircraft noise reduction, engine nozzle and fan components acoustic and performance research.

Unique in testing capabilities and size, the AAPL dome is sixty-five feet high and 130 feet in diameter, providing an anechoic testing environment for engine component research and development. To provide a reflection free acoustic environment, custom-designed 2-foot thick fiberglass wedges were mounted on the dome's interior walls and floor areas adjacent to the test rigs. The acoustically treated dome walls were also designed specifically to attenuate sound. Together, these elements provide an echo-free testing environment that exceeds the acoustic research testing objectives set forth by NASA and industry.

AAPL provides three state-of-the-art acoustic test rigs: Nozzle Acoustic Test Rig (NATR), Small Hot Jet Acoustic Rig (SHJAR), and the Advanced Noise Control Fan (ANCF).

Nozzle Acoustic Test Rig (NATR):
Designed specifically for acoustic and aerodynamic testing of advanced nozzle concepts, the Nozzle Acoustic Test Rig (NATR), a 53-in. diameter, free-jet acoustic wind tunnel, is used to test a variety of aircraft technologies at simulated take-off and landing flight conditions up to Mach 0.30. The High Flow Jet Exit Rig (HFJER) is used to mount test nozzle hardware within NATR.

Located 50 ft from a test model, two fixed microphone arrays are used to acquire sideline and fly-by acoustic data simultaneously. The data is processed and analyzed in real time during testing, improving data quality while reducing time and costs. AAPL is the largest acoustic facility in the world to feature a far-field measurement arena used for propulsion simulations.

Small Hot Jet Acoustic Rig (SHJAR):
The Small Hot Jet Acoustic Rig (SHJAR) provides researchers with an all-in-one platform to economically evaluate thrust performance, acoustic performance, and plume turbulence characteristics of new nozzle concepts.

SHJAR can conduct laser-based plume turbulence studies with Particle Imaging Velocimetry (PIV), Shawdowgraphy, Schlieren, and a traversing plume-survey that can acquire high-resolution temperature and pressure profiles.

A 10-ft custom-built far-field measurement arena is used to obtain sideline or fly-by acoustic data. The data collected is processed and analyzed in real time during testing, optimizing test utilization and data quality while reducing time and costs.

Advanced Noise Control Fan (ANCF):
The Advanced Noise Control Fan (ANCF) test bed was developed to test noise reduction concepts, noise measurement concepts, and provide a flexible and realistic aero-acoustic source for CAA code verification. The unique capability of the ANCF is the rotating rake measurement system that obtains both radial and circumferential mode measurements for the inlet and exhaust ducts. It is used for both Advanced Noise control experiments and general fan aero-acoustic research.
 
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Facility Fact Sheets
Aero-Acoustic Propulsion Laboratory (AAPL)
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9'x15' Low Speed Wind Tunnel (9x15)
Evaluating aerodynamic performance and acoustic
characteristics.
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Last Updated: January 24, 2007