A validated virtual prototyping approach for avoiding wind turbine tonality

Although aero-acoustic noise is considered as the dominant source of wind turbine noise, mechanical noise, coming from gearbox or generator, could - especially when it contains audible tonal components - results in non-conformity to local noise regulations. This becomes more stringent when wind turbines are installed closer to urbanised areas. An international consortium of German and Belgian partners active in wind turbine development – consisting of wind turbine OEM, component manufacturers and research institutions - has set up the European Eureka research project ALARM. Within this 3 years project that started in 2012 the different partners with each their area of expertise are joining forces to advance the state-of-the-art in the field of wind turbine vibro-acoustic assessment. This project covers all aspects of mechanical wind turbine noise from gear excitation, mechanical transfer paths, vibration insulation up to acoustic radiation and transmission. All those different aspects are analysed both from simulation side as well as from measurement side both on component level (gears, gearbox, bushings) and on wind turbine level. This paper gives a high level overview of the entire ALARM project, and focuses on a specific work package: simulation of the gearbox structural transfer path. Insight is given on the modelling approach and the extensive validation campaign (both on component and on assembly level) of this flexible multi-body model. The paper presents a method to interpret and evaluate the results of the structural model in a clear and structured way such that design optimisation becomes feasible. Simulation and validation results are discussed and results of investigations to lower noise and vibration values are presented.status: publishe