Numerical investigation and aerodynamic simulation of Darrieus H-rotor wind turbine at low Reynolds numbers

ABSTRACT

In order to select an airfoil suitable for the wind tunnel testing on a three-bladed Darrieus H-rotor wind turbine, several symmetrical National Advisory Committee for Aeronautics (NACA) 4-digit, NACA 4-digit, NACA 5-digit, and Selig airfoils with chord Reynolds numbers ($\mathrm{R}{\mathrm{e}}_{\mathrm{c}}$) of 17,890, 35,780, and 53,670 were studied. To achieve higher aerodynamic performance at Re of 17,890 to 53,670, the NACA0015 airfoil was selected. The lift coefficient ($\mathrm{R}{\mathrm{e}}_{\mathrm{c}}$) of the NACA0015 airfoil after shape modification has reached values of 0.788 to 0.936 at Re of 35,780 and 0.925 to 1.027 at Re of 53,670 with the same stall angle ($\mathrm{A}\mathrm{o}{\mathrm{A}}_{\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{l}\mathrm{l}}$) in both investigated Re, according to the results of modifying the airfoil’s thickness and chord. Additionally, the NACA0015 modified airfoil’s maximum lift-to-drag ratio coefficient (${\mathrm{C}}_{\mathrm{L}}/{\mathrm{C}}_{\mathrm{D}}$) increased by 34.01% and 17.94% at Re of 35780 and 53,670, respectively. Likewise, the analysis showed that the NACA0015 modified airfoil’s maximum performance coefficient (${\mathrm{C}}_{\mathrm{P}}$) increased from 0.129, 0.242, 0.285, 0.308, and 0.33 to 0.152, 0.272, 0.307, 0.331, and 0.354 at Re of 100,000, 150000, 200000, 250000, and 300,000, respectively. As well as the findings demonstrated that the XFOIL code provides the most accurate overall prediction results at low Re.

KEYWORDS:

• Airfoil
• Low Reynolds numbers
• Aerodynamic
• Lift coefficient
• Simulation

Disclosure statement

No potential conflict of interest was reported by the authors.

Nomenclature

${\mathrm{C}}_{\mathrm{L}}/{\mathrm{C}}_{\mathrm{D}}$	=	Lift-to-Drag Ratio
A	=	Swept Area
$\omega$	=	Angular Velocity
${\mathrm{C}}_{\mathrm{D}}$	=	Drag Coefficient
${\mathrm{U}}_{\mathrm{\infty }}$	=	Wind Speed
Δt	=	Time Step Size
${\mathrm{C}}_{\mathrm{L}}$	=	Lift Coefficient
${\mathrm{C}}_{\mathrm{L}}$	=	Performance coefficient

Additional information

Notes on contributors

Hossein Seifi Davari

Hossein Seifi Davari is president of research and development with Solar Turbibe Arta Energy (STAE). His research interests include clean energy, wind and water turbines. Seifi Davari holds a BS degrees in mechanical engineering and machinery mechanics agricultural engineering and MSc degree in mechanical engineering from Chabahar Maritime University.

Shahriar Kouravand

Shahriar Kouravand is an Associate Professor of Mechanical Engineering University of Tehran. His research interests include heat recovery, MEMS, machining, pollution reduction, roughness, and renewable energy.

Mohsen Seify Davari

Mohsen Seifi Davari is vice-president of research and development with Solar Turbine Arta Energy (STAE). His research interests include construction, wind and water turbines. Seifi Davari holds a BS degree in civil engineering from payame noor university, and Master’s student in civil engineering from Islamic Azad University Germi branch.

Zahra Kamalnejad

Zahra Kamalnejad is a Bachelor’s student architectural engineering from Islamic Azad University Ardabil branch. Her research interests include architectural engineering, design, and renewable energy.