Effects of root Gurney flaps on the aerodynamic performance of a horizontal axis wind turbine

The present study comprises steady state, two-dimensional computational investigations performed on NACA 0012 airfoil to analyze the effect of Gurney flap (GF) on airfoil aerodynamics using k-e RNG turbulence model of FLUENT. Airfoil with GF is analyzed for six different heights from 0.5% to 4% of the chord length, seven positions from 0% to 20% of the chord length from the trailing edge, and seven mounting angles from 30° to 120° with the chord. Computed values of lift and drag coefficients with angle of attack are compared with experimental values and good agreement is found at low angles of attack. In addition static pressure distribution on the airfoil surface and pathlines and turbulence intensities near the trailing edge are present. From the computational investigation, it is recommended that Gurney flaps with a height of 1.5% chord be installed perpendicular to chord and as close to the trailing edge as possible to obtain maximum lift enhancement with minimum drag penalty.

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Computational Investigations on the Effects of Gurney Flap on Airfoil Aerodynamics

It is projected that, in the following years, the wind-energy industry will maintain its rapid growth over the last few decades. Such growth in the industry has been accompanied by the desirability and demand for larger wind turbines aimed at harnessing more power. However, the fact that massive turbine blades inherently experience increased fatigue and ultimate loads is no secret, which compromise their structural lifecycle. Accordingly, this demands higher overhaul-and-maintenance (O&M) costs, leading to higher cost of energy (COE). Introduction of flow-control devices on the wind turbine is a plausible solution to this issue. Flow-control mechanisms feature the ability to effectively enhance/suppress turbulence, advance/delay flow transition, and prevent/promote separation, leading to enhancement in aerodynamic and aeroacoustics performance, load alleviation and fluctuation suppression, and eventually wind turbine power augmentation. These flow-control devices are operated primarily under two schemes: passive and active control. Development and optimization of flow-control devices present the potential for reduction in the COE, which is a major challenge against traditional power sources. This review performs a comprehensive and up-to-date literature survey of selected flow-control devices, from their time of development up to the present. It contains a discussion on the current prospects and challenges faced by these devices, along with a comparative analysis centered on their aerodynamic controllability. General considerations and conclusive remarks are presented after the discussion.

https://www.mdpi.com/1996-1073/14/5/1268/pdf

Review of Flow-Control Devices for Wind-Turbine Performance Enhancement

Steady state, two-dimensional computational investigations performed on NACA 0012 airfoil to analyze the effect of variation in Reynolds number on the aerodynamics of the airfoil without and with a Gurney flap of height of 3% chord are presented in this paper. RANS based one-equation Spalart-Allmaras model is used for the computations. Both lift and drag coefficients increase with Gurney flap compared to those without Gurney flap at all Reynolds numbers at all angles of attack. The zero lift angle of attack seems to become more negative as Reynolds number increases due to effective increase of the airfoil camber. However the stall angle of attack decreased by 2° for the airfoil with Gurney flap. Lift coefficient decreases rapidly and drag coefficient increases rapidly when Reynolds number is decreased below critical range. This occurs due to change in flow pattern near Gurney flap at low Reynolds numbers.

/pdf/effect-of-reynolds-number-on-aerodynamics-of-airfoil-with-4sxsx06j0w.pdf

Effect of Reynolds Number on Aerodynamics of Airfoil with Gurney Flap

Gurney flap is a miniature lift-enhancement device installed at the airfoil trailing edge and has been successfully applied to fixed wing aircraft and low-speed horizontal wind turbines. In this ar...

https://journals.sagepub.com/doi/pdf/10.1177/1687814018803804

Experimental and numerical study on the performance of an axial fan with a Gurney flap

Steady state, two dimensional numerical investigations are performed on NACA 0012 airfoil to analyze the performance of 5 different RANS based turbulence models on 4 different density grids in terms of aerodynamic characteristics of airfoils at a Reynolds Number of 3x10 6 . The purpose of this study is to choose the most accurate turbulence model which will be used to determine the effect of Gurney Flap and Synthetic Jet on airfoils in near future. Data obtained from this exhaustive series of numerical investigation with the help of FLUENT is used to plot C P , C L and C D vs. AoA. The best results are obtained with a grid consisting of 2,00,000 nodes and the k-e RNG turbulence model. Also, good results were obtained from the k-e Realizable model and k-w SST model.

Shubham Jain

Papers

Computational Investigations on the Effects of Gurney Flap on Airfoil Aerodynamics

Effect of Reynolds Number on Aerodynamics of Airfoil with Gurney Flap

Grid and Turbulence Model-based Exhaustive Analysis of NACA 0012 Airfoil