Noise Source Localization on a Small Wind Turbine Using a Compact Microphone Array with Advanced Beamforming Algorithms: Part II — A Study of Mechanical Noise from Nacelle Using a Wind Turbine Drive Train Simulator

Abstract

The main goal of this study was to separate and evaluate the noise contribution of each sub-component of a small scale wind turbine drive train that contributes to the overall mechanical noise inside the nacelle of a small (8 kW) wind turbine. The experiments were performed in a drive train simulator that housed the drive train of a Viryd 8000 wind turbine. Different wind speeds were simulated on the test stand through a drive system consisting of a motor, gearbox and flywheel. In order to evaluate the overall sound generation single microphone acoustic measurements were made. The frequency of sound generation was observed to be the same as that of vibrations of the drive train measured using two accelerometers. Sound radiated by each component of the drive train was evaluated through acoustic beamforming using a compact microphone array in conjunction with advanced beamforming algorithms. A strong relationship between the drive train power generation, and sound emitted by various mechanical components was observed. A unique contribution of this study is our ability to localize, separate and quantify noise from sub-components in a complex functioning wind turbine drive train.