Towards accurate CFD simulations of vertical axis wind turbines at different tip speed ratios and solidities: Guidelines for azimuthal increment, domain size and convergence

By A. Rezaeiha, H. Montazeri, B. Blocken. 2018

207 citations recorded by the source corpus.

The accuracy of CFD simulations of vertical axis wind turbines (VAWTs) is known to be significantly associated with the computational parameters, such as azimuthal increment, domain size and number of turbine revolutions before reaching a statistically steady state condition (convergence). A detailed review of the literature, however, indicates that there is a lack of extensive parametric studies investigating the impact of the computational parameters. The current study, therefore, intends to systematically investigate the impact of these parameters, on the simulation results to guide the execution of accurate CFD simulations of VAWTs at different tip speed ratios (λ) and solidities (σ). The evaluation is based on 110 CFD simulations validated with wind-tunnel measurements for two VAWTs. Instantaneous moment coefficient, Cm, and power coefficient, CP, are studied for each case using unsteady Reynolds-averaged Navier-Stokes (URANS) simulations with the 4-equation transition SST turbulence model. The results show that the azimuthal increment dθ is largely dependent on tip speed ratio. For moderate to high λ, the minimum requirement for dθ is 0.5° while this decreases to 0.1° at low to moderate λ. The need for finer time steps is associated to the flow complexities related to dynamic stall on turbine blades and blade-wake interactions at low λ. In addition, the minimum distance from the turbine center to the domain inlet and outlet is 15 and 10 times the turbine diameter, respectively. It is also shown that 20–30 turbine revolutions are required to ensure statistically converged solutions. The current findings can serve as guidelines towards accurate and reliable CFD simulations of VAWTs at different tip speed ratios and solidities.

Subfields: Aerospace Engineering, Computational Mechanics, Environmental Engineering

View Paper: https://www.semanticscholar.org/paper/2985e0838086b7f0621a4712c88d0a132f7dfa5f

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In Aerospace Engineering

1. H. Montazeri
2. A. Rezaeiha
3. Sadra Sahebzadeh
4. B. Blocken
5. Joachim Hansen
6. I. Tzanakis
7. M. Mahak
8. Carlo Gualtieri

In Computational Mechanics

1. H. Montazeri
2. A. Rezaeiha
3. Sadra Sahebzadeh
4. B. Blocken

In Environmental Engineering

1. H. Montazeri
2. A. Rezaeiha
3. Sadra Sahebzadeh
4. B. Blocken
5. Carlo Gualtieri

Citations in the corpus

• Numerical modelling and optimization of vertical axis wind turbine pairs: A scale up approach (2021, result): “k-ε is the most frequently applied turbulence model for analysing VAWTs [9], however, recent papers within the field of VAWTs [9,15] recommended applying the SSTmodel instead of the k-εmodel as it gives results that are closer to the experimental data.”
• Towards optimal layout design of vertical-axis wind-turbine farms: Double rotor arrangements (2020, methodology): “In addition, asymmetric VAWT wakes in the lateral direction have been reported in previous experimental studies [27,49,50] as well as validated numerical studies [31,32]; meaning that downstream turbines in the Φ = +15 and − 15 arrangements are located in different regions of the upstream turbine’s ”
• Towards optimal aerodynamic design of vertical axis wind turbines: Impact of solidity and number of blades (2018, methodology): “The size of the computational domain is based on the guidelines for CFD simulations of VAWTs [63,64].”