Fluid Mechanics (FLU)

The section focuses on fluid dynamics applied for wind turbine aerodynamics, hydrodynamics, aeroacoustics, aero-elasticity and turbulence in wind farms and implements the research in education, software and cooperation with industry.

The Section for Fluid Mechanics focuses on development, testing, and the use of methods for predicting loadings and power production of wind turbines, for designing airfoils and rotor blades, for simulating wind conditions in and about wind farms, and for determining noise emission from wind turbines. The methods comprise both numerical software and experimental techniques that are utilized to validate and test the theoretical results. The activities are subdivided into aerodynamics, hydrodynamics, and aeroacoustics.

Aerodynamics deal with the design of wind turbine airfoils and rotors. Although wind turbines have existed for many years, there is still a potential to refine the aerodynamic characteristics of the rotor. The reason for this is, partly, that wind turbine rotors still increase in size and therefore put more demand on a detailed and optimized design of the rotor geometry. Another issue of utmost importance is to incorporate the characteristics of the incoming wind in the design, as the wind is dominated by gusts and turbulence, which may impact rotor performance significantly. Today, most wind turbines are placed in large wind farms, which create their own micro-meteorological wind conditions. As these conditions are generated by the wakes of the wind turbines themselves, the simulation of a single wind turbine typically involves the influence of the neighbouring wind turbines. Another related aerodynamic subject concerns simulations of complete wind farms in order to optimize their layout in the planning phase, as well as to determine the power yield of existing wind farms. In short, the focus of the aerodynamic research at FLU ranges from design of airfoils to wind farm optimization.

Today, wind turbines are often erected offshore, where they mainly are fixed to the seabed on supporting substructures or, at large water depths, on floating platforms. This requires knowledge regarding the influence of waves, tides, and currents on the wind turbine tower and substructure. Essentially, this also requires a combined analysis of the aerodynamics and hydrodynamic forces acting on the turbine. The hydrodynamic research at FLU concerns the development and application of advanced software to simulate the impact of waves and currents on the support structure of wind turbines. Another issue is the validation of the numerical models and the assessment of the quality of the obtained results. This is carried out by performing experiments in dedicated wind and water tunnels, of which some are placed at DTU and others at neighbouring research institutions, such as DHI.

Wind power cannot be generated without emitting noise. Hence, noise is an intrinsic problem associated with wind power generation. The most severe wind turbine noise originates from the aerodynamics of the wind turbine rotor through the interaction between the solid structure of the rotor blade and the incoming wind. At FLU, we develop aeroacoustic models to localize the origin of the noise and to simulate the noise emission to neighbouring surroundings. The developed models are combined with the aerodynamic design tools to optimize airfoils and wind turbine rotors to reduce noise without compromising power performance. The aeroacoustic tools are also employed to predict noise from complete wind farms and to determine the influence of the landscape on the noise emission patterns. The overall goal of our research is to alleviate noise nuisances by exploiting intelligent control of the wind turbines and by designing wind turbines with low noise emission.


Head of Section

Jens Nørkær Sørensen
Professor
DTU Wind Energy
+45 45 25 43 14