Measurement of Flow Separation Noise on a Full-scale Wind Turbine

摘要

An investigation has been conducted into the acoustic effects of aerodynamic flow separation on the blades of a wind turbine. Experimentation was conducted on a Siemens Wind Power 2.3 MW machine with a rotor diameter of 108 m. Flow separation was intentionally induced using modified turbine controller settings, and the acoustic signature is measured using twelve microphones in a one rotor radius ring about the tower base. Flow separation was detected using static pressure ports at several locations along the blade span. Separation noise is shown to increase the noise of the turbine by at least 8 dB across all frequencies and up to 13 dB. Overall noise increases by at least 10 dB(A). Results also show that the stall noise directivity deviates significantly from the expected compact dipole pattern-even as low as 100 Hz. The driving physical mechanism for the unexpected directivity pattern is as of yet unknown.