Measurements of Interaction and Scattered Modes in a Mixed Bypass/Core Duct due to Multiple Rotating Sources

摘要

A Honeywell Aerospace model scale research fan module was tested in both Honeywell's Subscale Fan Rig and NASA's 9x15 Low Speed Wind Tunnel. Modal measurements were acquired in both facilities to document the modal content. The Rotating Rake Measurement System was utilized to measure the acoustic duct modes in the NASA 9x15 Low Speed Wind Tunnel fan installation. In the Honeywell Subscale Fan Rig, two in-duct phased microphone arrays were installed to simultaneously measure fan noise in the inlet and bypass exhaust ducts. Prior Rotating Rake and Array Beamforming measurements have occurred in environments with a single rotating source interacting with a stationary source to produce duct modes at the fan harmonics. The scale model high-speed research fan had two rotating sources, a rotor and a booster, which were on the same shaft. This allowed for an expansion of duct mode measurement and analysis techniques.