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.

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.

scholarly journals Experimental investigation of Mini Gurney Flaps in combination with vortex generators for improved wind turbine blade performance

2021 ◽  
Author(s):  
Jörg Alber ◽  
Marinos Manolesos ◽  
Guido Weinzierl-Dlugosch ◽  
Johannes Fischer ◽  
Alexander Schönmeier ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Wind Turbine ◽  
Leading Edge ◽  
Suction Side ◽  
Rotor Blades ◽  
Force Balance ◽  
Vortex Generators ◽  
Gurney Flaps ◽  
First Case ◽  
The Impact

Abstract. This wind tunnel study investigates the aerodynamic effects of Mini Gurney flaps (MGFs) and their combination with vortex generators (VGs) on the performance of airfoils and wind turbine rotor blades. VGs are installed on the suction side aiming at stall delay and increased maximum lift. MGFs are thin angle profiles that are attached at the trailing edge in order to increase lift at pre-stall operation. The implementation of both these passive flow control devices is accompanied by a certain drag penalty. The wind tunnel tests are conducted at the Hermann- Föttinger Institut of the Technische Universität Berlin. Lift is determined with a force balance and drag with a wake rake for static angles of attack from −5° to 17° at a constant Reynolds number of 1.5 million. The impact of different MGF heights including 0.25 %, 0.5 % and 1.0 % and an uniform VG height of 1.1 % of the chord length are tested on three airfoils that are characteristic for different sections of large rotor blades. Furthermore, the clean and the tripped baseline cases are considered. In the latter, leading edge transition is forced by means of Zig Zag (ZZ) turbulator tape. The preferred configurations are the smallest MGF on the NACA63(3)618 and the AH93W174 (mid to tip blade region) and the medium sized MGF combined with VGs on the DU97W300 (root to mid region). Next, the experimental lift and drag polar data is imported into the software QBlade in order to design a generic rotor blade. The blade performance is simulated with and without the add-ons based on two case studies. In the first case, the retrofit application on an existing blade mitigates the adverse effects of the ZZ tape. Stall is delayed and the aerodynamic efficiency is partly recovered leading to an improvement of the power curve. In the second case, the new design application allows for the design of a more slender blade while maintaining the power output. Moreover, the alternative blade appears to be more resistant against forced leading edge transition.

A Numerical Study Into the Influence of Leading Edge Tubercles on the Aerodynamic Performance of a Highly Cambered High Lift Airfoil Wing at Different Reynolds Numbers

2020 ◽  
Author(s):  
Amr Abdelrahman ◽  
Amr Emam ◽  
Ihab Adam ◽  
Hamdy Hassan ◽  
Shinichi Ookawara ◽  
...  
Keyword(s):  
Control Method ◽  
Numerical Study ◽  
Leading Edge ◽  
Suction Side ◽  
Reynolds Numbers ◽  
Passive Flow Control ◽  
Passive Flow ◽  
Stall Angle ◽  
Lifting Surfaces ◽  
Lift And Drag

Abstract Through the last two decades, many studies have demonstrated the ability of leading-edge protrusions (tubercles), inspired from the pectoral flippers of the humpback whale, to be an effective passive flow control method for the stall phase of an airfoil in some cases depending on the geometrical features and the flow regime. Nevertheless, there is a little work associated with revealing tubercles performance for the lifting surfaces with a highly cambered cross-section, used in numerous applications. The present work aims to investigate the effect of implementing leading edge tubercles on the performance of an infinite span rectangular wing with the highly cambered S1223 foil at different flow regimes. Two sets; baseline one and a modified with tubercles have been studied at Re = 0.1 × 106, 0.3 × 106 and 1.5 × 106 using computational fluid dynamics with a validated model. The numerical results demonstrated that Tubercles have the ability to entirely alter the flow structure over the airfoil, confining the separation to troughs, hence, softening the stall characteristics. However, the tubercle modification expedites the presence of the stalled flow over the suction side, lowering the stall angle for the three mentioned Reynolds numbers. While, no considerable difference occurs in lift and drag before the stall.

Experimental Analysis on a Model of a Small Ducted Wind Turbine Equipped with Passive Flow Control Devices

2021 ◽  
Author(s):  
Elena-Alexandra Chiulan ◽  
Costin Ioan Cosoiu ◽  
Andrei-Mugur Georgescu ◽  
Anton Anton ◽  
Mircea Degeratu
Keyword(s):  
Flow Control ◽  
Wind Turbine ◽  
Experimental Analysis ◽  
Passive Flow Control ◽  
Passive Flow ◽  
Flow Control Devices ◽  
Control Devices

Study of three types of wave leading edge on the performance of industrial turbine blade cascade

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hamed Ghandi ◽  
Reza Aghaei Togh ◽  
Abolghasem Mesgarpoor Tousi
Keyword(s):  
Turbine Blade ◽  
Flow Separation ◽  
Numerical Solutions ◽  
Incidence Angle ◽  
Leading Edge ◽  
Content Type ◽  
Passive Flow Control ◽  
Passive Flow ◽  
Geometrical Features ◽  
Control Methodology

Purpose The blade profile and its geometrical features play an important role in the separation of the boundary layer on the blade. Modifying the blade geometry, which might lead to the delay or elimination of the flow separation, can be considered as a passive flow control methodology. This study aims to find a novel and inexpensive way to reduce loss with appropriate modifications on the leading edge of the turbine blade. Design/methodology/approach Three types of wave leading edges were designed with different wavelengths and amplitudes. The selected numbers for the wave characteristics were based on the best results of previous studies. Models with appropriate and independent meshing have been simulated and studied by a commercial software. The distribution of the loss at different planes and mid-plane velocity vectors were shown. The mass flow average of loss at different incidence angles was calculated for the reference blade and modified ones for the sake of comparison. Findings The results show that in all three types of modified blades compared to the reference blade, the elimination of flow separation is observed and therefore the reduction of loss at the critical incidence angle of I = –15°. As the amplitude of the wave increased, the amount of loss growing up, while the increase in wavelength caused the loss to decrease. Originality/value The results of the present numerical analysis were validated by the laboratory results of the reference blade. The experimental study of modified blades can be used to quantify numerical solutions.

Flow Visualization Study of Passive Flow Control Features on a Film-Cooled Turbine Blade Leading Edge

2010 ◽  
Author(s):  
Daniel R. Carroll ◽  
Paul I. King ◽  
James L. Rutledge
Keyword(s):  
Turbine Blade ◽  
Flow Direction ◽  
Water Channel ◽  
Leading Edge ◽  
Surface Modifications ◽  
Stagnation Line ◽  
Single Row ◽  
Passive Flow Control ◽  
Passive Flow ◽  
Flow Surface

A water channel study was conducted on a cylindrical leading edge model of a film-cooled turbine blade to assess the effects of surface modifications on film spreading. A single radial coolant hole located 21.5° from the stagnation line, angled 20° to the surface and 90° to the flow direction supplied dyed coolant flow. Surface modifications included a variety of dimples upstream and downstream of the coolant hole and transverse trenches milled coincident with the coolant hole. Compared to the unmodified surface, a single row of small cylindrical or spherical dimples upstream of the coolant hole steadies the jet at blowing ratios up to M = 0.75. Medium and large spherical dimples downstream of the coolant hole have a similar effect, but none of the dimple geometries studied affect the coolant jet above M = 0.75. A single-depth, square-edged transverse trench spreads the coolant spanwise, increasing the coverage of a single coolant hole more than two times. This trench suffers from coolant blow-out above M = 0.50, but a deeper, tapered-depth trench entrains and spreads the coolant very effectively at blowing ratios above M = 0.50. The tapered trench prevents jet liftoff and is the only geometry studied that holds the coolant closer to the surface than the unmodified coolant hole.

Numerical Simulation on the Flow Control by Mounting Indented Gurney Flaps for a Wind Turbine

2012 ◽  
Vol 512-515 ◽  
pp. 623-627 ◽  
Author(s):  
Wan Li Zhao ◽  
Xiao Lei Zheng
Keyword(s):  
Numerical Simulation ◽  
Wind Turbine ◽  
Numerical Investigation ◽  
Wind Turbines ◽  
Aerodynamic Performance ◽  
Optimal Position ◽  
Gurney Flaps ◽  
Turbine Performance ◽  
Gurney Flap ◽  
Practical Engineering

Numerical investigation of large thick and low Reynolds airfoil of wind turbines by mounting indented Gurney flaps was carried out. The influenced rules of the position of Gurney flaps on the aerodynamic performance of airfoil under same height of flaps were achieved, and the optimal position of Gurney flap was presented. At last, the mechanism of wind turbine performance controlled by Gurney flap was discussed. The results can provide the theoretical guidance and technical support to wind turbines control in practical engineering.

Wake Analysis of a Finite Width Gurney Flap

2015 ◽  
Author(s):  
D. Holst ◽  
A. B. Bach ◽  
C. N. Nayeri ◽  
C. O. Paschereit ◽  
G. Pechlivanoglou
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Large Scale ◽  
Reynolds Numbers ◽  
Tip Vortex ◽  
Finite Width ◽  
Low Reynolds Numbers ◽  
Gurney Flaps ◽  
Gurney Flap ◽  
Pitch System

The results of stereo Particle-Image-Velocimetry measurements are presented in this paper to gain further insight into the wake of a finite width Gurney flap. It is attached to an FX 63-137 airfoil which is known for a very good performance at low Reynolds numbers and is therefore used for small wind turbines and is most appropriate for tests in the low speed wind tunnel presented in this study. The Gurney flaps are a promising concept for load control on wind turbines but can have adverse side effects, e.g. shedding of additional vortices. The investigation focuses on frequencies and velocity distributions in the wake as well as on the structure of the induced tip vortices. Phase averaged velocity fields are derived of a Proper-Orthogonal-Decomposition based on the stereo PIV measurements. Additional hot-wire measurements were conducted to analyze the fluctuations downstream of the finite width Gurney flaps. Experiments indicate a general tip vortex structure that is independent from flap length but altered by the periodic shedding downstream of the flap. The influence of Gurney flaps on a small wind turbine is investigated by simulating a small 40 kW turbine in Q-Blade. They can serve as power control without the need of an active pitch system and the starting performance is additionally improved. The application of Gurney flaps imply tonal frequencies in the wake of the blade. Simulation results are used to estimate the resulting frequencies. However, the solution of Gurney flaps is a good candidate for large scale wind turbine implementation as well. A FAST simulation of the NREL 5MW turbine is used to generate realistic time series of the lift. The estimations of control capabilities predict a reduction in the standard deviation of the lift of up to 65%. Therefore finite width Gurney flaps are promising to extend the lifetime of future wind turbines.

Investigation of a Passive Flow Control Device in an S-Duct Inlet of a Propulsion System With High Subsonic Flow

2018 ◽  
Author(s):  
Asad Asghar ◽  
Satpreet Sidhu ◽  
William D. E. Allan ◽  
Grant Ingram ◽  
Tom M. Hickling ◽  
...  
Keyword(s):  
Flow Control ◽  
Complex Geometry ◽  
Control Device ◽  
Pressure Recovery ◽  
Passive Flow Control ◽  
Passive Flow ◽  
Flow Control Device ◽  
Inner Radius ◽  
Selection Of ◽  
Numerical Approaches

S-Ducts have wide application on air vehicles with embedded engines. The complex geometry is known to lead to separation downstream of curved profiles. This paper reports the influences on that flow of passive flow control geometries. In these experiments, stream-wise tubercles were applied in an effort to improve the internal performance of S-duct diffusers, parameters including pressure recovery, distortion and swirl. The test articles were tested with the high subsonic (Ma = 0.8) flow and were manufactured using 3D printing. Stream-wise static pressure and exit-plane total pressure were measured in a test rig using surface pressure taps and a 5-probe rotating rake, respectively; the baseline and variant S-ducts were simulated through computational fluid dynamics. The experiments showed that some subtle improvements to the S-Duct distortion could be achieved through careful selection of tubercle geometry. Generally, the recovered flow downstream of the inner radius of the second bend of the S-duct deteriorated, but overall pressure recovery improved. The simulations were useful in characterizing swirl, whereas experiments were not so equipped. Adjustments to the numerical approaches resulted in reasonable agreement with the experiments.

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