DNV GL and Partners Tackle Outdated Turbulence Models

DNV GL has, together with global partners, launched a Joint Industry Project (JIP)  aimed at creating a better understanding of turbulence modelling to reduce uncertainty in the design of wind farms. 

The JIP “Validation of Turbulence Models” will focus on developing a new Best Practice for the validation of turbulence models. By jointly developing guidelines in the form of a Best Practice document the project will improve accuracy on site-specific load assessments, leading to a reduction in the cost of wind energy, according to DNV GL.

To design wind turbines and wind farms, the industry currently relies on wind turbulence models that were developed decades ago when wind turbines were smaller than modern turbine types, DNV GL says.

With the increased size of wind turbines, current turbulence models result in large fatigue load variations with differences of up to 20%. Furthermore, existing turbulence models are often insufficiently applicable to other site-conditions beyond flat terrain and neutral stability.

By providing a platform to discuss challenges such as the most appropriate turbulence model parameters and whether parameters should differ onshore and offshore, stakeholders are developing a mutual alignment on key questions that are vital to moving the industry forward, according to DNV GL.

The JIP will collect onshore and offshore wind measurement data from more than 30 global sites, considering onshore, offshore and coastal influences in the analysis. By validating key turbulence parameters and evaluating their load impact, the JIP will provide guidance for optimal wind turbulence design and site assessments in a new Best Practice document.

Jose Simon, Senior Engineer at DNV GL – Energy Renewables Certification, responsible for setting up this JIP, said: “In the planning process, it became apparent that there is currently area for improvement on turbulence modelling, especially for site-specific turbulence. Talking to different wind industry stakeholders during the preparation for this project highlighted the necessity of aligning industry expectations on turbulence in a Best Practice. To gain a deeper understanding of turbulence modelling the industry needs to collaborate and this project provides a unique platform to do so.”

The participants in the JIP include a global range of wind farm developers, wind turbine manufactures and research institutes, including DONG Energy Wind Power, DTU Wind Energy, GE Global Research, National Renewable Energy Laboratory (NREL), Siemens Wind Power AS, SSE Renewables Developments LTD, Statoil Petroleum AS, Suzlon, Vattenfall AB and others.

Jens Gjerding, Chief Principal Specialist from Vattenfall, said: “With the requirement of reducing the cost of wind energy, it is necessary to improve our knowledge. Not only for reducing price/loads, but also to be sure that we are not too optimistic. Some subjects need more information than what is available at individual companies. The ‘Validation of Turbulence Model’ using data from many sources is the only way for further development.”