Turbulence distortion and blockage in the induction zone of a horizontal axis turbine

Wind tunnel measurements of the incident turbulent velocity fields and axial forces on a horizontal axis turbine and porous disc analogues are reported. The models were tested in both a simulated atmospheric boundary layer (ABL) and in grid turbulence, allowing for a range of turbulence length scale...

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Bibliographic Details
Published in:Journal of fluid mechanics 2024-11, Vol.1000, Article A25
Main Authors: Gouder, Kevin, Milne, Ian A., Graham, Mike
Format: Article
Language:English
Subjects:
Aerodynamics
Atmospheric boundary layer
Atmospheric turbulence
Axial forces
Boundary layers
Design
Diameters
Distortion
Fatigue tests
Flow resistance
Fluid dynamics
JFM Papers
Load fluctuation
Potential flow
Ratios
Rotors
Scale (ratio)
Turbines
Turbulence
Turbulence measurement
Turbulent boundary layer
Turbulent flow
Velocity
Velocity distribution
Wind measurement
Wind power
Wind tunnel testing
Wind tunnels
Wind turbines
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Summary:Wind tunnel measurements of the incident turbulent velocity fields and axial forces on a horizontal axis turbine and porous disc analogues are reported. The models were tested in both a simulated atmospheric boundary layer (ABL) and in grid turbulence, allowing for a range of turbulence length scale to rotor diameter ratios to be considered. A theoretical framework to account for the combined effect of distortion and potential flow blocking in the induction zone is presented. In the case of very large length-scale turbulence to diameter ratios, where distortion effects are minimal, a quasi-steady approach is adopted for the effect of blocking. For the small length-scale ratio limit, the method is developed from the classical analyses for rapid distortion of turbulence and blockage from flow through a porous sheet of resistance. For general length-scale ratios, an efficient prediction method based on interpolation between the two length-scale ratio extremes is established. For very large length-scale ratios, a quasi-steady theory without distortion is appropriate for a rotor or disc in a simulated ABL. The small length-scale theory is applicable for tests conducted in grid turbulence. The results of the study can inform the prediction and interpretation of typical measurements of turbulence within the induction zone and the fluctuating loads on a rotor, at both prototype and full scale. This is of particular importance to fatigue load assessments.
ISSN:0022-1120
1469-7645
DOI:10.1017/jfm.2024.713