scholarly journals Numerical Analysis on the Effectiveness of Gurney Flaps as Power Augmentation Devices for Airfoils Subject to a Continuous Variation of the Angle of Attack by Use of Full and Surrogate Models

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1877
Author(s):  
Piotr Wiśniewski ◽  
Francesco Balduzzi ◽  
Zbigniew Buliński ◽  
Alessandro Bianchini
Keyword(s):  
Angle Of Attack ◽  
Vertical Axis ◽  
Urban Environments ◽  
Design Solution ◽  
Performance Improvements ◽  
Gurney Flaps ◽  
Blade Thickness ◽  
Multidimensional Interpolation ◽  
Gurney Flap ◽  
Computational Fluid Dynamics Cfd

The disclosing of new diffusion frontiers for wind energy, like deep-water offshore applications or installations in urban environments, is putting new focus on Darrieus vertical-axis wind turbines (VAWTs). To partially fill the efficiency gap of these turbines, aerodynamic developments are still needed. This work in particular focuses on the development of a mathematical model that allows predicting the possible performance improvements enabled in a VAWT by application of the Gurney flaps (GFs) as a function of the blade thickness, the rotor solidity and geometry of the Gurney flap itself. The performance of airfoil with GFs was evaluated by means of detailed simulations making use of computational fluid dynamics (CFD). The accuracy of the CFD model was assessed against the results of a dedicated experimental study. In the simulations, a dedicated method to simulate cycles of variation of the angle of attack similar to those taking place in a cycloidal motion (rather than purely sinusoidal ones) was also developed. Based on the results from CFD, a multidimensional interpolation based on the radial basis functions was conducted in order to find the GF design solution that provides the highest efficiency for a given turbine in terms of airfoil and solidity. The results showed that, for the selected study cases based on symmetric airfoils, the GF positioned facing outwards from the turbine, which provides the upwind part of the revolution, can lead to power increments ranging from approximately 30% for the lower-solidity turbine up to 90% for the higher-solidity turbine. It was also shown that the introduction of a GF should be coupled with a re-optimization of the airfoil thickness to maximize the performance.

Performance Improvements for a Vertical Axis Wind Turbine by Means of Gurney Flap

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Yan Yan ◽  
Eldad Avital ◽  
John Williams ◽  
Jiahuan Cui
Keyword(s):  
Wind Turbine ◽  
Stokes Equations ◽  
Numerical Study ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Navier Stokes ◽  
Speed Ratio ◽  
Vertical Axis Wind Turbine ◽  
Performance Improvements ◽  
Gurney Flap

Abstract A numerical study was carried out to investigate the effects of a Gurney flap (GF) on the aerodynamics performance of the NACA 00 aerofoil and an associated three-blade rotor of a H-type Darrieus wind turbine. The flow fields around a single aerofoil and the vertical axis wind turbine (VAWT) rotor are studied using unsteady Reynolds-averaged Navier–Stokes equations (URANS). The height of GF ranges from 1% to 5% of the aerofoil chord length. The results show that the GF can increase the lift and lift-to-drag ratio of the aerofoil as associated with the generation of additional vortices near the aerofoil trailing edge. As a result, adding a GF can significantly improve the power coefficient of the VAWT at low tip speed ratio (TSR), where it typically gives low power production. The causing mechanism is discussed in detail, pointing to flow separation and dynamic stall delay.

scholarly journals Aerodynamic Effects of Gurney Flaps on the Rotor Blades of a Research Wind Turbine

2020 ◽  
Author(s):  
Jörg Alber ◽  
Rodrigo Soto-Valle ◽  
Marinos Manolesos ◽  
Sirko Bartholomay ◽  
Christian Navid Nayeri ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Leading Edge ◽  
Control Device ◽  
Rotor Blades ◽  
Passive Flow Control ◽  
Performance Improvements ◽  
Gurney Flaps ◽  
Passive Flow ◽  
Gurney Flap ◽  
Horizontal Axis Wind Turbines

Abstract. This paper investigates the aerodynamic impact of Gurney flaps on a research wind turbine of the Hermann-Föttinger Institute at the Technische Universität Berlin. The rotor radius is 1.5 meters and the blade configurations consist of the clean and the tripped baseline cases emulating the effects of forced leading edge transition. The wind tunnel experiments include three operation points based on tip speed ratios of 3.0, 4.3 and 5.6, reaching Reynold numbers of approximately 250,000. The measurements are taken by means of three different methods; Ultrasonic Anemometry in the wake, surface pressure taps in the mid-span blade region and strain gauges at the blade root. The retrofit application consists of two Gurney flap heights of 0.5 % and 1.0 % in relation to the chord length, which are implemented perpendicular to the pressure side at the trailing edge. As a result, the Gurney flap configurations evoke performance improvements in terms of the axial wake velocities, the angles-of-attack and the lift coefficients. The enhancement of the root bending moments imply an increase of both the rotor torque and the thrust. Furthermore, the aerodynamic impact appears to be more pronounced in the tripped case compared to the clean case. Gurney flaps are considered a worthwhile passive flow-control device in order to alleviate the adverse effects of early separation and leading edge erosion of horizontal axis wind turbines.

Parametric Investigation of Gurney Flaps for the Use on Wind Turbine Blades

2017 ◽  
Author(s):  
Joerg Alber ◽  
Georgios Pechlivanoglou ◽  
Christian Oliver Paschereit ◽  
Jochen Twele ◽  
Guido Weinzierl
Keyword(s):  
Turbine Blades ◽  
Simulation Software ◽  
Design Solution ◽  
Data Sets ◽  
Optimized Design ◽  
Power Performance ◽  
Parametric Investigation ◽  
Gurney Flaps ◽  
Gurney Flap ◽  
Lift And Drag

This paper presents a strategy to model the aerodynamic Gurney flap effect on two-dimensional airfoils and subsequently on the rotor blade performance of horizontal axis wind turbines. The first part consists of the parametric investigation of 26 airfoil polar data-sets, derived from different, but comparable, wind tunnel experiments. They are evaluated and processed in terms of the lift and drag increase caused by Gurney flaps in comparison to each Baseline configuration. Consequently, a model is developed, transforming Baseline- into Gurney flap polar data for varying flap-heights. The results of the emerging Gurney Flap Polar Calculator are validated against the experimental lift and drag curves. In the second part, the blade design of the NREL 5 MW Reference Turbine is modified by implementing polar data-sets of varying Gurney flap-heights, which are imported into the rotor simulation software QBlade. Thereupon, blade optimization strategies are examined regarding the two main Gurney flap applications on rotor blades: the retrofit and the design solution. The optimized retrofit solution on existing blades indicates power performance improvements, albeit at the expense of increasing structural loads. The optimized design solution on to-be-constructed blades, on the other hand, suggests chord-length reductions, while keeping the performance characteristics on a similar or even enhanced level. It is concluded that aerodynamic improvements are achieved by relatively small Gurney flap-heights, which are applied at specific blade positions.

scholarly journals Aerodynamic Characteristics of Airfoil and Vertical Axis Wind Turbine Employed with Gurney Flaps

2021 ◽  
Vol 13 (8) ◽  
pp. 4284
Author(s):  
Yosra Chakroun ◽  
Galih Bangga
Keyword(s):  
Wind Turbine ◽  
Numerical Solutions ◽  
Vertical Axis ◽  
Power Production ◽  
Aerodynamic Characteristics ◽  
Maximum Height ◽  
Vertical Axis Wind Turbine ◽  
Time Step ◽  
Gurney Flaps ◽  
Gurney Flap

In the present studies, the effects of Gurney flaps on aerodynamic characteristics of a static airfoil and a rotating vertical axis wind turbine are investigated by means of numerical approaches. First, mesh and time step studies are conducted and the results are validated with experimental data in good agreement. The numerical solutions demonstrate that the usage of Gurney flap increases the airfoil lift coefficient CL with a slight increase in drag coefficient CD. Furthermore, mounting a Gurney flap at the trailing edge of the blade increases the power production of the turbine considerably. Increasing the Gurney flap height further increases the power production. The best performance found is obtained for the maximum height used in this study at 6% relative to the chord. This is in contrast to the static airfoil case, which shows no further improvement for a flap height greater than 0.5%c. Increasing the angle of the flap decreases the power production of the turbine slightly but the load fluctuations could be reduced for the small value of the flap height. The present paper demonstrates that the Gurney flap height for high solidity turbines is allowed to be larger than the classical limit of around 2% for lower solidity turbines.

scholarly journals Aerodynamic effects of Gurney flaps on the rotor blades of a research wind turbine

2020 ◽  
Vol 5 (4) ◽  
pp. 1645-1662
Author(s):  
Jörg Alber ◽  
Rodrigo Soto-Valle ◽  
Marinos Manolesos ◽  
Sirko Bartholomay ◽  
Christian Navid Nayeri ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Leading Edge ◽  
Control Device ◽  
Rotor Blades ◽  
Passive Flow Control ◽  
Performance Improvements ◽  
Gurney Flaps ◽  
Passive Flow ◽  
Gurney Flap ◽  
Horizontal Axis Wind Turbines

Abstract. This paper investigates the aerodynamic impact of Gurney flaps on a research wind turbine of the Hermann-Föttinger Institute at the Technische Universität Berlin. The rotor radius is 1.5 m, and the blade configurations consist of the clean and the tripped baseline cases, emulating the effects of forced leading-edge transition. The wind tunnel experiments include three operation points based on tip speed ratios of 3.0, 4.3, and 5.6, reaching Reynolds numbers of approximately 2.5×105. The measurements are taken by means of three different methods: ultrasonic anemometry in the wake, surface pressure taps in the midspan blade region, and strain gauges at the blade root. The retrofit applications consist of two Gurney flap heights of 0.5 % and 1.0 % in relation to the chord length, which are implemented perpendicular to the pressure side at the trailing edge. As a result, the Gurney flap configurations lead to performance improvements in terms of the axial wake velocities, the angles of attack and the lift coefficients. The enhancement of the root bending moments implies an increase in both the rotor torque and the thrust. Furthermore, the aerodynamic impact appears to be more pronounced in the tripped case compared to the clean case. Gurney flaps are considered a passive flow-control device worth investigating for the use on horizontal-axis wind turbines.

Improvement of Torque Performance of a Vertical Axis Type Marine Turbine for a Water Current Generation System

2010 ◽  
Author(s):  
Tomoki Ikoma ◽  
Shintaro Fujio ◽  
Koichi Masuda ◽  
Chang-Kyu Rheem ◽  
Hisaaki Maeda
Keyword(s):  
Turbine Blades ◽  
Angle Of Attack ◽  
Cross Flow ◽  
Vertical Axis ◽  
Hydrodynamic Forces ◽  
Water Current ◽  
Current Channel ◽  
Marine Current ◽  
Water Turbine ◽  
Type Water

This paper describes the possibility of an improvement of torque performance and hydrodynamic forces on a vertical axis type water turbine, used for marine current generating system. The water turbine analyzed here is based on a Darrieus turbine with vertical blades. We considered possibilities of controlling the angle of attack of blades in order to improve the starting performance and to reduce energy loss during the rotation of the turbine. We used blade-element/ momentum theory in order to investigate the variations appearing in torque performance when the angle of attack were controlled. We also proved the validity of our predictions of hydrodynamic forces on the blade and the turbine, made through CFD calculation, by comparing them with the results of corresponding model tests in a current channel. In the corresponding model test we investigated not only the hydrodynamic forces on the turbine with three fixed blades, but also the inline force and the cross-flow force on the rotating turbine with three blades. Regarding the cyclic pitching of turbine blades, results suggest that significant increase in average turbine torque is possible.

scholarly journals Kontrol Angle of Attack untuk Optimasi Daya padaVertical Axis Wind Turbine Tipe Darrieus

2020 ◽  
Vol 8 (3) ◽  
pp. 492
Author(s):  
WAHYU AULIA NURWICAKSANA ◽  
BUDHY SETIAWAN ◽  
IKA NOER SYAMSIANA ◽  
SEPTYANA RISKITASARI
Keyword(s):  
Wind Turbine ◽  
Angle Of Attack ◽  
Vertical Axis ◽  
Speed Ratio ◽  
Trial And Error ◽  
Proportional Integral Derivative ◽  
Vertical Axis Wind Turbine ◽  
Average Efficiency ◽  
Proportional Integral ◽  
Tip Speed Ratio

ABSTRAKVAWT (Vertical Axis Wind Turbine) tipe Darrieus NACA0015 merupakan salah satu model dari turbin angin yang bekerja dengan menggunakan angin sebagai sumber penggerak. Namun dari hasil pengamatan, kecepatan angin yang ada tidak konstan setiap saat. Sehingga dari permasalahan ini perlu suatu kontrol yaitu dengan mengendalikan sudut kerja blade VAWT yang dikenal dengan kontrol angle of attack (AoA). Prinsip kerja kontrol AoA yaitu sudut blade diatur agar VAWT bekerja secara optimum dan dapat meningkatkan efisiensi. Metode kontrol AoA menggunakan PID (Proportional–Integral–Derivative) dengan memberikan nilai trial and error pada Kp, Ki, Kd. VAWT ini menggunakan konstanta TSR (Tip Speed Ratio) yaitu 4. Hasil dari penelitian ini yaitu daya yang dihasilkan VAWT dengan kontrol AoA mendapatkan rata-rata efisiensi sebesar 5.16%, sedangkan VAWT tanpa kontrol mendapatkan efisiensi sebesar 3.49%. Sehingga dapat disimpulkan bahwa dengan kontrol AoA, rata-rata efisiensi dayanya naik sebesar 1.67% dari yang tanpa kontrol.Kata Kunci: Kontrol Angle of Attack (AoA), VAWT, TSR, Efisiensi ABSTRACTVAWT (Vertical Axis Wind Turbine) type Darrieus NACA0015 is one model of a wind turbine that works by using wind as a source of propulsion. Conditions from observations, wind speeds that are not constant every time. So from this problem needs control VAWT by controlling the working angle of the VAWT blade is the angle of attack control (AoA). The principle AoA control is that the blade angle adjusted so that the VAWT works optimally and can improve the efficiency. AoA control method uses PID (Proportional-Integral-Derivative) by providing trial and error values for Kp, Ki, Kd. VAWT uses TSR (Tip Speed Ratio) constant which is 4. The results of this research, VAWT with AoA control get an average efficiency of 5.16%, while without control gets an average efficiency of 3.49%. So it can be concluded that with AoA control, the average power efficiency increases by 1.67% from those without control.Keywords: Angle of Attack (AoA) Control, VAWT, TSR, Efficiency

scholarly journals VISUAL ANALYTICS WEB PLATFORM FOR DETECTING HIGH WIND ENERGY POTENTIAL IN URBAN ENVIRONMENTS BY EMPLOYING OGC STANDARDS

2020 ◽  
Vol XLIV-4/W1-2020 ◽  
pp. 71-74
Author(s):  
A. Koukofikis ◽  
V. Coors
Keyword(s):  
Wind Energy ◽  
Visual Analytics ◽  
Vertical Axis ◽  
Urban Environments ◽  
Small Scale ◽  
High Wind ◽  
Energy Potential ◽  
Web Architecture ◽  
Wind Energy Potential ◽  
Ogc Standards

Abstract. We propose a server-client web architecture identifying areas with high wind energy potential by employing 3D technologies and OGC standards. The assessment of a whole city or sub-regions will be supported by integrating Computational Fluid Dynamics (CFD) with historical wind sensor readings. The results, in 3D space, of such analysis could be used for locating installation points of small-scale vertical axis wind turbines in an urban area.

scholarly journals CFD for Helical Type Vertical Axis Wind Turbine

2019 ◽  
Vol 9 (2S4) ◽  
pp. 474-476
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Computer Aided Design ◽  
Flow Characteristics ◽  
Vertical Axis ◽  
Urban Environments ◽  
Vertical Axis Wind Turbine ◽  
Wind Turbine System ◽  
Twisted Blade ◽  
Aided Design

Vertical axis wind turbines are most effective for home energy generation especially in urban environments. Wind energy creates a stand-alone energy source that is relied on any place. The main criteria for this work is the design of micro wind turbines for all kinds of applications. Design of Twisted Blade Micro-Wind Turbine system is accomplished using computer aided design with Computational Fluid Dynamics (CFD). The flow characteristics in the wind turbine blade were analyzed by varying its twist ratio. The wind turbines with vertical axis utilize the wind from any direction with no yaw mechanism. The risk of blade ejection besides catching wind from all the directions is avoided by using the helical tye vertical axis wind turbine.

Sign in / Sign up

Export Citation Format

Share Document