Numerical investigation of aerodynamic characteristics of naca 23112 using passive flow control technique – gurney flaps

Abstract

Since its inception in the early 1970s by Daniel Gurney, the Gurney flaps have proven to be an effective means of enhancing the aerodynamic performance of an airfoil. Current applications of Gurney flaps include wind turbine blades, race car spoilers, helicopter rotors, and certain high-lift devices. This study compares the influence of Gurney flaps on flow characteristics and the effects of design parameters of the flap, namely the length and position of the flap on a NACA 23,112 airfoil. A review of the studies conducted so far has shown that studies have been carried out on a select few airfoils only and mainly studied the effects of variation of only one of the characteristics, like length, position, or angle. This paper has been crried out to find the optimum balance between these design parameters. Additionally, this paper aims to investigate the accuracy and feasibility of numerical investigation methods to estimate the aerodynamic characteristics of airfoils and wings compared to conventional techniques like wind tunnel testing. This cost-effective computation method is less susceptible to external factors like weather changes. The CFD process also allows testing at conditions that might otherwise be impractical to test in wind tunnels. The workflow comprised a review of literature, validation of solver settings, preparation and testing of the model, extraction of results and analysis of results. Autodesk Fusion360 and Ansys Workbench 22R1 were used to make and test the models. The airfoil designs were tested at Re = 2 × 10⁶, at angles of attack varying from 0° to 15°. The GF height ranged from 1% to 3% chord and placed at 95% to 100% chord. A reliable methodology has been arrived at and validated by implementing the best practices prescribed for CFD. The k-$\mathit{\omega }$ SST turbulence model, along with second-order spatial discretization, was used. Coefficients of lift and drag were considered the study parameters. Gurney flaps were found to increase the performance of the airfoil, and better results were obtained at higher angles of attack. The modified designs noted the separation point further downstream than the baseline model. Overall, the presence of Gurney flaps proved beneficial over the baseline model.

Keywords:

• Gurney flaps
• Computational fluid dynamics (CFD)
• Circulation
• Aerodynamic efficiency
• Ansys Fluent
• Autodesk Fusion360

Nomenclature

c	=	chord length
Cl	=	Coefficient of lift
Cd	=	Coefficient of drag
D	=	Drag force
HAWT	=	Horizontal axis wind turbine
L	=	Lift force
LDA	=	Laser Doppler anemometry
LE	=	Leading edge
MiTE	=	Miniature trailing edge
TE	=	Trailing edge
TSR	=	Tip speed ratio
Vair	=	free-stream velocity
VAWT	=	Vertical axis wind turbine
$G_k$	=	generation of turbulence kinetic energy due to the mean velocity gradients
$\mathrm{\Gamma }\mathit{\omega }$ and ${\mathrm{\Gamma }}_k$	=	effective diffusivity of k and $\mathit{\omega }$
ρair	=	Density of air
Yk and Yω	=	turbulent dissipation of k and ω
Dω	=	cross-diffusion terms
Sk and Sω	=	user-defined source terms.
X-YY	=	length of the flap in mm and position of the flap from LE as a percentage of chord

Acknowledgments

Firstly, we would like to thank Dr Anil Rana, Director, Manipal Institute of Technology, Manipal, for providing the necessary support and infrastructure to carry out this project. We would also like to extend our heartiest gratitude to Dr Dayananda Pai K, Head of the Department of Automobile and Aeronautical Engineering, Manipal Institute of Technology, Manipal, for providing us with the opportunity and necessary guidance to undertake this study.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors declare that no funds, grants, or other financial support were received during the preparation of this manuscript.

Notes on contributors

Vandan Chinnappa

Vandan Chinnappa—worked on conceptualization, methodology, investigation, numerical study, and writing—original draft.

  Srinivas G

SrinivasG is a faculty in the Department of Aeronautical and Automobile engineering at Manipal Institute of Technology – Manipal Academy of Higher Education (MAHE). He is a doctorate from Manipal Academy of Higher Education –MAHE (Institute of Eminence)- Manipal, India. He is experienced in the field of Aircraft aerodynamics, Aircraft Propulsion, Rocket and Missiles Aerodynamics, Air Transportation system, computational fluid mechanics and has published more than 40+ articles in leading Aerospace and Mechanical Science related journals. He has mentored several UG and Graduate students and is the Faculty Advisor of MIT’s collegiate and one of the world’s leading student sounding rocketry design and Research club “thrustMIT”. He is an institute coordinator and member of prestigious Institution of Power Engineers (IPowerE). His research interest includes Aircraft Propulsion, Rocket Propulsion, Aerodynamics of Rockets and Missiles, Aircraft Design, Computational Fluid Dynamics, Mechanics of Fluids and Aerodynamics, and is currently exploring topics related to Transonic flow and Hypersonic flow regimes applications.