ACOUSTIC PREDICTIONS USING MEASURED PRESSURES FROM A MODEL ROTOR IN THE DNW

A contemporary design, 4-bladed United Technologies model rotor with p ressure-instrumented blades was tested in the Duits-Nederlandse Windtu nnel. Simultaneous acoustic and pressure measurements were made for a wide range of operating conditions. Microphones were positioned at a n umber of locations in the flow forward of the rotor to measure rotor t hickness noise and high-speed impulsive noise (in the rotor plane), an d blade-vortex interaction noise (forward and below the rotor plane). The blade surface pressure data are used as aerodynamic input to WOPWO P, which is a rotor noise prediction program that predicts thickness a nd loading noise. The predicted results using WOPWOP are compared to t he measured noise levels for cases where either the noise, blade-vorte x interaction noise, or high-speed impulsive noise is the dominant noi se mechanism. The comparisons show regions of good agreement, as well as areas where further improvement is necessary.