NASA Glenn Research Center operates six world-class experimental facilities

Research teams at the NASA Glenn Research Center perform experiments in world-class facilities. The facilities include the 9- by 15-Foot Low-Speed Wind Tunnel, the Aero-Acoustic Propulsion Laboratory, the Small Hot Jet Acoustic Rig, the Nozzle Acoustic Test Rig, the DGEN AeroPropulsion Research Turbofan, and the Acoustical Testing Laboratory.

The 9- by 15-Foot Low-Speed Wind Tunnel is designed to study aircraft engine aerodynamics and acoustics at takeoff and landing conditions. Major modifications were completed in 2019. A new 5-sensor traversing microphone rake helps measure sound produced by scale experimental propulsors.

The Aero-Acoustic Propulsion Laboratory is a dual-purpose 65-foot radius geodesic dome. The dome contains 17,000 custom-designed 2-ft thick fiberglass wedges mounted to absorb sound and prevent reflections. The laboratory was constructed in 1993 and was the first known free-standing geodesic dome to include materials to reduce sound transmission.

The Small Hot Jet Acoustic Rig can test single stream nozzles up to 5 cm in diameter, Mach 2.0 and 800 K. Researchers have been developing advanced flow measurement techniques including Rayleigh Scattering, Raman Scattering, digital Schlieren, and real-time Particle Image Velocimetry. In 2006, researchers used the first time-resolved particle image velocimetry to measure space-time correlations of turbulent velocities in hot jets.

The Nozzle Acoustic Test Rig is a free-jet wind tunnel that simulates take-off and landing flight conditions up to Mach 0.35. A jet engine simulator with up to three streams of air at various pressures and temperatures simulates turbofan engine flow. The rig evaluates advanced nozzle concepts and has a 30-year history of jet noise research.

Chevron nozzles seen on aircraft today were first developed during a NASA-led test campaign in 1997. The facility tests scale models of nozzles from military and commercial aircraft engines. Tests measure the noise likely produced by supersonic airliners and identify technologies to reduce that noise.