Airframe noise generated by commercial aircraft at landing approach is a barrier to the achievement of desired noise reduction goals for the next generation of aircraft.

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Tests have been conducted on a JT15D-1 turbofan engine both statically and at simulated forward speed in the Ames 12 x 24 m Wind Tunnel. Both far-field acoustic data and unsteady pressure data from transducers mounted on the fan blades were acquired. Results showed a sound power reduction of about 10 dB in the farfield acoustic levels with simulated forward speed over that measured without forward speed. Blade-mounted transducer results showed rotor-turbulence interaction dominated the noise field at very low speeds while an interaction between the rotor and internal struts dominated at higher speeds. Results are presented to show the effects of varying engine revolutions per minute, changing the angle of attack of the engine inlet to tunnel flow, and mounting an aircraft wing to simulate an installation condition on a actual aircraft.