Numerical investigation of the wake-diffusion rotor concept

Numerical investigation of the wake-diffusion rotor concept

Mordasov, Dmitrij (TU Delft Aerospace Engineering)

van der Laan, Maarten Paul (mentor)
Baungaard, Mads Christian (mentor)
Watson, S.J. (mentor)
Knauer, Andreas (mentor)
Modesti, D. (graduation committee)
Schmehl, R. (graduation committee)

Delft University of Technology
Technical University of Denmark

European Wind Energy Masters (EWEM)

2022-08-19

With the growing global utilisation of wind energy, lowering of its levelised cost of energy is pursued. This effort is hindered by wind turbine wakes and their detrimental effects on wind farm profitability. Most currently researched wake mitigation methods are based on wind farm system-level interventions, and there is a research gap on individual wind turbine design wake alleviation measures.

This thesis investigates the wake-diffusion rotor concept, a wind turbine design with an outboard shifted thrust distribution along the blade, and its effects on wake mitigation and power generation in wind farms.
Three wind turbine rotors with equivalent thrust coefficient are modelled as actuator disks in a RANS CFD software PyWakeEllipSys, corresponding to an inboard shifted thrust distribution, a conventional thrust distribution, and an outboard shifted thrust distribution representing the wake-diffusion rotor concept. Investigated scenarios include a single wind turbine and rows of three and ten wind turbines aligned to the inflow.
Compared to the baseline case, outboard thrust distribution produces lower wake velocity deficits, increased momentum transfer and increased turbulence generation. The wake-diffusion rotor concept increases the wind farm power generation by 3.8 % and 2.5 % in the three and ten wind turbine row scenarios respectively, with the largest relative gain in wind turbine power of 13.9 % for the second wind turbine in the row. Consecutive wind turbines in the row experience diminishing gains. The inboard shifted thrust distribution had opposite effects for all of these aspects.
The benefits in wake mitigation and power generation in wind farms from using the wake-diffusion rotor concept are concluded to come from higher turbulence mixing caused by the outboard shifted thrust distribution. Recommendations on its use for maximum effectiveness are given. Future research could focus on the design implementation of this concept, investigate combinations with other wake mitigation methods and perform parametric wind farm AEP studies.

Wind turbine
Wakes
Aerodynamics
RANS
Blade loads
Turbine blade design
Wind turbine wakes
Wind power

http://resolver.tudelft.nl/uuid:f4a34434-a186-4127-aedd-d9d8f5e62c2a

Student theses

master thesis

© 2022 Dmitrij Mordasov