https://www.nasa.gov/centers/glenn/events/tour_dome.html NASA's Dome of silence Join the NASA Glenn Research Center for a tour of the Aero-Acoustic Propulsion Laboratory (AAPL), and see where some of the world's most advanced aircraft noise-reduction ideas are developed and tested. The Aero-Acoustic Propulsion Laboratory’s acoustically designed dome protects residential communities from the laboratory’s high noise levels. Unique in size and appearance, this world-class facility stands 65-feet high and 130-feet in diameter and has 17,000 two-foot-thick fiberglass wedges mounted on its walls and floor. Designed to prevent echoes and reverberations, the wedges give the facility a futuristic, maze-like appearance. The Nozzle Acoustic Test Rig, one of three test rigs in the AAPL, is used to evaluate jet engine nozzle noise at speeds up to 220 miles per hour. April 11, 2015 Go Under the Dome of Silence Join the NASA Glenn Research Center for a tour of the Aero-Acoustic Propulsion Laboratory (AAPL), and see where some of the world's most advanced aircraft noise-reduction ideas are developed and tested. The Aero-Acoustic Propulsion Laboratory’s acoustically designed dome protects residential communities from the laboratory’s high noise levels. Unique in size and appearance, this world-class facility stands 65-feet high and 130-feet in diameter and has 17,000 two-foot-thick fiberglass wedges mounted on its walls and floor. Designed to prevent echoes and reverberations, the wedges give the facility a futuristic, maze-like appearance. The Nozzle Acoustic Test Rig, one of three test rigs in the AAPL, is used to evaluate jet engine nozzle noise at speeds up to 220 miles per hour. tours_dome_226.jpg One of three test rigs in the Aero-Acoustic Propulsion Lab, the Nozzle Acoustic Test Rig is used to evaluate jet engine nozzle noise at speeds up to 220 miles per hour. Credits: NASA Tour buses depart from the Main Gate of NASA John H. Glenn Research Center at the following times: 10:00 a.m. 11:00 a.m. 12:00 p.m. 1:00 p.m. Please note the following important guidelines: Advanced registration guarantees admission to the tour that begins at the Briefing Center. Access to the Saturday tour program is limited to U.S. citizens and Lawful Permanent Residents (LPRs). All adult visitors are required to present government-issued photo identification, and LPRs are required to present their Permanent Resident Card. This includes bus drivers for scheduled groups. NASA reserves the right to limit the use of cameras and cell phones during the tour. More Information: > Facility Tour Schedule > Glenn Research Center Events Last Updated: July 30, 2015 Editor: NASA Administrator =================== http://facilities.grc.nasa.gov/aapl/ 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 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. AAPL provides three state-of-the-art test rigs: Nozzle Acoustic Test Rig (NATR), Small Hot Jet Acoustic Rig (SHJAR) and Advanced Noise Control Fan (ANCF). Nozzle Acoustic Test Rig (NATR) Research Objectives Supports acoustic research on nozzle and engine components Description 53-in.-diameter free-jet acoustic wind tunnel Used to test a variety of aircraft technologies at simulated take-off and landing flight conditions up to Mach 0.30 High Flow Jet Exit Rig (HFJER) Capabilities: Test nozzle concepts with diameters up to 8 inches Simulated nozzle exhaust conditions up to 1425°F with a nozzle pressure ratio of 4.5 Airflows up to 20 lbm/sec Nozzle thrusts up to 2000 lbf Single and dual air flow configurations to simulate the engine core and fan flows of turbofan nozzle concepts Advanced Diagnostic Testing Capabilities: Temperature-pressure traversing plume survey Particle Image Velocimetry (PIV) Laser Doppler Velocimetry (LDV) Phased-array acoustic source identification Schlieren/Shawdowgraphy Model Data and Control System Capabilities Pressure Systems ESP is an off the shelf electronically scanned pressure system. The system consists of numerous 32 port, rack mounted modules from +/-2.5 PSID to +500 PSID, located outside the test chamber. Each module has a check pressure to assure the module is performing correctly and can be calibrated in place using up to 5 highly accurate calibration pressures to maintain the overall system accuracy of +/-0.05% of range. This calibration is performed every 2 hours. For the NATR, the following ranges are typically provided: 352 ports +/- 15 PSID Barometric Ref 192 ports +/- 100 PSID Barometric Ref 32 port + 500 PSID Barometric Ref Data System - Escort Escort, the steady state data acquisition system, uses a DEC Alpha microprocessor to provide: An X window based system Real time on-line acquisition of analog signals Conversion of raw 10Hz filtered digitized Neff data to engineering units Computed performance calculations, which can be displayed in a variety of tabular and graphical formats. Limit checking on all selected changes 1 second update rate Escort can stand alone to meet all secure test requirements or it can be connected to a central processing cluster, which facilitates software application development, downloading of software, uploading and storage of facility tables, post processing of data and transmitting of data to a data collector for archival storage. For the 1x1, Escort provides the following: Accuracy for the Neff 400 is +/- 0.05% of range 384 channels of which 320 are available for the test article 120 temperatures from CA type K thermocouples 96 temperatures from type N 24 temperatures from type R Acoustic Capability NATR sits inside a geodesic dome specifically designed to allow for Far field (50 feet) acoustic measurements of nozzle generated noise. The system has an array of 24 microphones positioned in an arc from 40 degrees to 165 degrees. An overhead array allows an additional 24 microphones to be positioned at a 25 degree from Vertical in a similar arc from 40 degrees to 165 degrees. ================== https://facilities.grc.nasa.gov/documents/TOPS/TopAAPL.pdf Data and info sheet =================== https://www.youtube.com/watch?v=OtJS3NG6hno Video of inside the dome =================== http://bethcooperacoustics.com/wp-content/uploads/2015/09/Large-Hemianechoic-Enclosure.pdf Paper detailing all facets of the site and its construction ================= https://facilities.grc.nasa.gov/aapl/video/AAPL.html NASA's information video about the facility - very informative =========== NASA photo gallery of the facility - best pictures