Pratt and Whitney's Advanced Ducted Propulsor Model is tested in NASA's 9x15-Foot Low-Speed Wind Tunnel.

The Advanced Research Nozzle, jointly developed by NASA and industry, has been tested in NASA's Aero-Acoustic Propulsion Laboratory.

A new technology for reducing fan blade noise, designed in partnership with Allison Engine Company, will benefit both current and future engines.

NASA Research A new approach to noise reduction is the active noise control effort. The primary principle of active noise control is to sense the noise disturbances in the engine and cancel them before they leave the engine. In effect, negative noise is made to cancel out the engine's sound waves so that no noise is heard. This is a multidisciplinary effort involving duct acoustics, controls and actuator/sensor design. NASA Glenn has a unique facility for this testing. The Active Noise Control Fan is a 4-ft-diameter low-speed fan designed specifically for active noise control testing. To date, several concepts have shown successful cancellation of selected acoustic modes. Because noise is the sum of all possible acoustic modes, the effort is still in its infancy, but it has potential high payoffs. Active noise control will contribute to the 6 db noise reduction goal of the AST program.