journalArticle
Rezaeiha
Abdolrahim
Montazeri
Hamid
Blocken
Bert
Aerodynamic performance
Characterization study
Design guideline
Offshore wind turbine
Urban wind turbine
Vertical axis wind turbine (VAWT)
Towards optimal aerodynamic design of vertical axis wind turbines: Impact of solidity and number of blades
The current study systematically analyzes the impact of solidity (σ) and number of blades (n) on the aerodynamic performance of 2-, 3- and 4-bladed Darrieus H-type vertical axis wind turbines (VAWTs). Solidity varies within the wide range of 0.09–0.36. A large number of operational parameters, i.e., tip speed ratio (λ), Reynolds number (Re), turbulence intensity and reduced frequency (K) are investigated to provide a deeper insight into the impact of σ and n on the dynamic loads on blades, the turbine performance and the wake. High-fidelity unsteady Reynolds-averaged Navier-Stokes (URANS) simulations, extensively validated with experiments, are employed. The results show that the turbine optimal tip speed ratio (λopt) is invariant to a newly-introduced parameter ‘σλ3’, regardless of the turbine geometrical and operational characteristics. In addition, a new correlation is derived to estimate λopt as a function of σ, which can also be employed to predict the optimal σ for a turbine with a given λ. It is also found that: (i) for constant-speed urban VAWTs, which due to the low mean wind speed in the urban environment, frequently operate at moderate to high λ, a relatively-low σ is optimal; (ii) an optimal VAWT is a moderately-high-solidity variable-speed rotor maintaining a relatively-low λ, where due to the large blade chord length the resulting Re and K are favorably high; (iii) within the turbine optimal operational range, turbine power coefficient (CP) is almost independent of n. The present findings support the optimal aerodynamic design of small-to large-scale VAWTs.
1129-1148
December 15, 2018
Towards optimal aerodynamic design of vertical axis wind turbines
http://www.sciencedirect.com/science/article/pii/S0360544218319704
2018-10-18T07:01:33Z
ScienceDirect
Energy
165
Energy
DOI 10.1016/j.energy.2018.09.192
ISSN 0360-5442