# Effects of Gurney Flaps on the Performance of a Horizontal Axis Ocean Current Turbine

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## Abstract

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## 1. Introduction

- The effect of Gurney flap height on the hydrodynamic characteristics of the airfoil at different angles of approach.
- The relationship between the dynamic performance of the airfoil and the Gurney flap height.
- The effect of different radial lengths of Gurney flaps on the hydrodynamic performance of the airfoil.

## 2. Geometric Description

#### 2.1. HAOCT Rotor Model

#### 2.2. Gurney Flaps

#### 2.3. Coefficients for Performance

## 3. Numerical Method

#### 3.1. Computation Domain and Boundary Conditions

#### 3.2. Mesh Generation

#### 3.3. Solution Settings and Validation of Numerical Methods

^{−5}. The gradient uses the least-squares cell-based algorithm.

## 4. Results and Discussion

#### 4.1. Hydrodynamic Performance of Gurney Flaps Height

#### 4.2. Effect of the Full-Length Gurney Flap on Turbine

#### 4.3. Hydrodynamic Performance of Gurney Flaps Radial Dimensions

## 5. Conclusions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## Nomenclature

$\lambda $ | Tip speed ratio |

$B$ | Number of blades |

${\omega}_{r}$ | Rotor rotation speed [rad/s] |

$\alpha $ | Angles of attack [°] |

U | Free-stream velocity [m/s] |

U’ | Local stream velocity [m/s] |

${T}_{i}$ | Turbulence intensity [%] |

$R$ | Rotor radius [m] |

$D$ | Rotor diameter [m] |

$L$ | Hub length [m] |

${R}_{h}$ | Hub radius [m] |

$l$ | Flap length [m] |

$h$ | Flap height [m] |

$r$ | Local radius [m] |

$c$ | Local chord length [m] |

${C}_{p}$ | Power coefficient |

${C}_{t}$ | Thrust coefficient |

## References

- Li, M.; Luo, H.; Zhou, S.; Senthil Kumar, G.M.; Guo, X.; Law, T.C.; Cao, S. State-of-the-Art Review of the Flexibility and Feasibility of Emerging Offshore and Coastal Ocean Energy Technologies in East and Southeast Asia. Renew. Sustain. Energy Rev.
**2022**, 162, 112404. [Google Scholar] [CrossRef] - Khan, M.Z.A.; Khan, H.A.; Aziz, M. Harvesting Energy from Ocean: Technologies and Perspectives. Energies
**2022**, 15, 3456. [Google Scholar] [CrossRef] - Bhuiyan, M.A.; Hu, P.; Khare, V.; Hamaguchi, Y.; Thakur, B.K.; Rahman, M.K. Economic Feasibility of Marine Renewable Energy: Review. Front. Mar. Sci.
**2022**, 9, 988513. [Google Scholar] [CrossRef] - Rehman, S.; Alhems, L.M.; Alam, M.M.; Wang, L.; Toor, Z. A Review of Energy Extraction from Wind and Ocean: Technologies, Merits, Efficiencies, and Cost. Ocean Eng.
**2023**, 267, 113192. [Google Scholar] [CrossRef] - Zhang, J.; Liu, S.; Guo, Y.; Sun, K.; Guan, D. Performance of a Bidirectional Horizontal-Axis Tidal Turbine with Passive Flow Control Devices. Renew. Energy
**2022**, 194, 997–1008. [Google Scholar] [CrossRef] - Satrio, D.; Suntoyo; Ramadhan, L.I. The Advantage of Flow Disturbance for Vertical-Axis Turbine in Low Current Velocity. Sustain. Energy Technol. Assess.
**2022**, 49, 101692. [Google Scholar] [CrossRef] - Yang, M.-H.; Gu, Z.-T.; Yeh, R.-H. Numerical and Experimental Analyses of the Performance of a Vertical Axis Turbine with Controllable-Blades for Ocean Current Energy. Energy Convers. Manag.
**2023**, 285, 117009. [Google Scholar] [CrossRef] - Tigabu, M.T.; Khalid, M.S.U.; Wood, D.; Admasu, B.T. Some Effects of Turbine Inertia on the Starting Performance of Vertical-Axis Hydrokinetic Turbine. Ocean Eng.
**2022**, 252, 111143. [Google Scholar] [CrossRef] - Nachtane, M.; Tarfaoui, M.; Goda, I.; Rouway, M. A Review on the Technologies, Design Considerations and Numerical Models of Tidal Current Turbines. Renew. Energy
**2020**, 157, 1274–1288. [Google Scholar] [CrossRef] - Kundu, P.; Sarkar, A.; Nagarajan, V. Improvement of Performance of S1210 Hydrofoil with Vortex Generators and Modified Trailing Edge. Renew. Energy
**2019**, 142, 643–657. [Google Scholar] [CrossRef] - Fan, M.; Sun, Z.; Yu, R.; Dong, X.; Li, Z.; Bai, Y. Effect of Leading-Edge Tubercles on the Hydrodynamic Characteristics and Wake Development of Tidal Turbines. J. Fluids Struct.
**2023**, 119, 103873. [Google Scholar] [CrossRef] - Mansi, A.; Aydin, D. The Impact of Trailing Edge Flap on the Aerodynamic Performance of Small-Scale Horizontal Axis Wind Turbine. Energy Convers. Manag.
**2022**, 256, 115396. [Google Scholar] [CrossRef] - Nanda, S.; Ahmed, S.; Warudkar, V.; Gautam, A. Effect of Uniformly Varying Width Leading-Edge Slots on the Aerodynamic Performance of Wind Turbine Blade. Mater. Today Proc.
**2023**, 78, 120–127. [Google Scholar] [CrossRef] - Barbarić, M.; Batistić, I.; Guzović, Z. Numerical Study of the Flow Field around Hydrokinetic Turbines with Winglets on the Blades. Renew. Energy
**2022**, 192, 692–704. [Google Scholar] [CrossRef] - Wang, J.J.; Li, Y.C.; Choi, K.-S. Gurney Flap—Lift Enhancement, Mechanisms and Applications. Prog. Aerosp. Sci.
**2008**, 44, 22–47. [Google Scholar] [CrossRef] - Basso, M.; Cravero, C.; Marsano, D. Aerodynamic Effect of the Gurney Flap on the Front Wing of a F1 Car and Flow Interactions with Car Components. Energies
**2021**, 14, 2059. [Google Scholar] [CrossRef] - Genest, B.; Dumas, G. Numerical Investigation into Single and Double Gurney Flaps for Improving Airfoil Performance. J. Aircr.
**2023**, 1–15. [Google Scholar] [CrossRef] - Fatahian, H.; Salarian, H.; Eshagh Nimvari, M.; Khaleghinia, J. Effect of Gurney Flap on Flow Separation and Aerodynamic Performance of an Airfoil under Rain and Icing Conditions. Acta Mech. Sin.
**2020**, 36, 659–677. [Google Scholar] [CrossRef] - Bianchini, A.; Balduzzi, F.; Di Rosa, D.; Ferrara, G. On the Use of Gurney Flaps for the Aerodynamic Performance Augmentation of Darrieus Wind Turbines. Energy Convers. Manag.
**2019**, 184, 402–415. [Google Scholar] [CrossRef] - Ye, X.; Hu, J.; Zheng, N.; Li, C. Numerical Study on Aerodynamic Performance and Noise of Wind Turbine Airfoils with Serrated Gurney Flap. Energy
**2023**, 262, 125574. [Google Scholar] [CrossRef] - Syawitri, T.P.; Yao, Y.-F.; Yao, J.; Chandra, B. The Effect of Gurney Flap on Flow Characteristics of Vertical Axis Wind Turbine. Int. J. Mod. Phys. B
**2020**, 34, 2040107. [Google Scholar] [CrossRef] - Syawitri, T.P.; Yao, Y.; Yao, J.; Chandra, B. Geometry Optimisation of Vertical Axis Wind Turbine with Gurney Flap for Performance Enhancement at Low, Medium and High Ranges of Tip Speed Ratios. Sustain. Energy Technol. Assess.
**2022**, 49, 101779. [Google Scholar] [CrossRef] - Zhang, Y.; Ramdoss, V.; Saleem, Z.; Wang, X.; Schepers, G.; Ferreira, C. Effects of Root Gurney Flaps on the Aerodynamic Performance of a Horizontal Axis Wind Turbine. Energy
**2019**, 187, 115955. [Google Scholar] [CrossRef] - Zhu, H.; Hao, W.; Li, C.; Ding, Q. Numerical Study of Effect of Solidity on Vertical Axis Wind Turbine with Gurney Flap. J. Wind Eng. Ind. Aerodyn.
**2019**, 186, 17–31. [Google Scholar] [CrossRef] - Kumar, P.M.; Samad, A. Introducing Gurney Flap to Wells Turbine Blade and Performance Analysis with OpenFOAM. Ocean Eng.
**2019**, 187, 106212. [Google Scholar] [CrossRef] - Bahaj, A.S.; Molland, A.F.; Chaplin, J.R.; Batten, W.M.J. Power and Thrust Measurements of Marine Current Turbines under Various Hydrodynamic Flow Conditions in a Cavitation Tunnel and a Towing Tank. Renew. Energy
**2007**, 32, 407–426. [Google Scholar] [CrossRef] - Batten, W.M.J.; Bahaj, A.S.; Molland, A.F.; Chaplin, J.R. Experimentally Validated Numerical Method for the Hydrodynamic Design of Horizontal Axis Tidal Turbines. Ocean Eng.
**2007**, 34, 1013–1020. [Google Scholar] [CrossRef] - Chandrasekhara, M.S. Optimum Gurney Flap Height Determination for “Lost-Lift” Recovery in Compressible Dynamic Stall Control. Aerosp. Sci. Technol.
**2010**, 14, 551–556. [Google Scholar] [CrossRef] - Molland, A.F.; Bahaj, A.S.; Chaplin, J.R.; Batten, W.M.J. Measurements and Predictions of Forces, Pressures and Cavitation on 2-D Sections Suitable for Marine Current Turbines. Proc. Inst. Mech. Eng. Part M J. Eng. Marit. Environ.
**2004**, 218, 127–138. [Google Scholar] [CrossRef] - He, X.; Wang, J.; Yang, M.; Ma, D.; Yan, C.; Liu, P. Numerical Simulation of Gurney Flap on SFYT15thick Airfoil. Theor. Appl. Mech. Lett.
**2016**, 6, 286–292. [Google Scholar] [CrossRef] - Bak, C.; Fuglsang, P.; Johansen, J.; Antoniou, I. Wind Tunnel Tests of the NACA 63-415 and a Modified NACA 63-415 Airfoil; Risoe National Lab.: Roskilde, Denmark, 2000; 107p. [Google Scholar]

**Figure 5.**Results of the numerical method validation: (

**a**) power coefficient and (

**b**) thrust coefficient.

**Figure 6.**Coefficient of pressure at different angles of attack for 2D airfoil: (

**a**) 4°, (

**b**) 12°, (

**c**) 16°.

**Figure 7.**Performance of 2D NACA 63815 at different angles of attack: (

**a**) lift coefficient, (

**b**) thrust coefficient, (

**c**) lift–drag ratio.

**Figure 11.**Turbine with different heights of Gurney flaps: (

**a**) power coefficient, (

**b**) thrust coefficient.

**Figure 13.**Pressure distribution on the pressure surface and suction surface of the blade when tip speed ratio is 6.

**Figure 14.**Turbine with different radial dimensions of Gurney flaps: (

**a**) power coefficient, (

**b**) thrust coefficient.

**Figure 16.**Pressure distribution on the pressure side and suction side of the blade when tip speed ratio is 6.

Number of blades $B$ | 3 |

Rotor diameter $D$ [m] | 0.8 |

Hub radius ${R}_{h}$ [m] | 0.05 |

Hub length $L$ [m] | 0.6 |

Rotor radius $R$ [m] | 0.4 |

Flap length $l$ [m] | 0, 0.4 R, 0.6 R, 0.8 R, R |

Flap height $h$ [m] | 0, 0.01 c, 0.02 c, 0.03 c |

Free-stream velocity $U$ [m/s] | 1.73 |

Turbulence intensity ${T}_{i}$ [%] | 2 |

Rotational speed ${\omega}_{r}$ [rad/s] | 8.65~38.925 |

Tip speed ratio $\lambda $ | 2~9 |

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## Share and Cite

**MDPI and ACS Style**

Mao, Z.; Zhang, T.; Yang, G.; Tian, W.
Effects of Gurney Flaps on the Performance of a Horizontal Axis Ocean Current Turbine. *J. Mar. Sci. Eng.* **2023**, *11*, 2188.
https://doi.org/10.3390/jmse11112188

**AMA Style**

Mao Z, Zhang T, Yang G, Tian W.
Effects of Gurney Flaps on the Performance of a Horizontal Axis Ocean Current Turbine. *Journal of Marine Science and Engineering*. 2023; 11(11):2188.
https://doi.org/10.3390/jmse11112188

**Chicago/Turabian Style**

Mao, Zhaoyong, Tianqi Zhang, Guangyong Yang, and Wenlong Tian.
2023. "Effects of Gurney Flaps on the Performance of a Horizontal Axis Ocean Current Turbine" *Journal of Marine Science and Engineering* 11, no. 11: 2188.
https://doi.org/10.3390/jmse11112188