Experimental investigations of flow over NACA airfoils 0021 and 4412 of wind turbine blades with and without Tubercles

Experimental investigations of wind turbine blades having NACA airfoils 0021 and 4412 with and without tubercles on the leading edge have been performed in a wind tunnel. It was found that the lift coefficient of the airfoil 0021 with tubercles was higher at Re = 1.2×105 and 1.69×105 in post critical region (at higher angle of attach) than airfoils without tubercles but this difference relatively diminished at higher Reynolds numbers and beyond indicating that there is no effect on the lift coefficients of airfoils with tubercles at higher Reynolds numbers whereas drag coefficient remains unchanged. It is noted that at Re = 1.69×105, the lift coefficient of airfoil without tubercles drops from 0.96 to 0.42 as the angle of attack increases from 15° to 20° which is about 56% and the corresponding values of lift coefficient for airfoil with tubercles are 0.86 and 0.7 at respective angles with18% drop.

Download Full-text

Wind Tunnel Experimental Study of Wind Turbine Airfoil Aerodynamic Characteristics

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.260-261.125 ◽

2012 ◽

Vol 260-261 ◽

pp. 125-129

Author(s):

Xin Zi Tang ◽

Xu Zhang ◽

Rui Tao Peng ◽

Xiong Wei Liu

Keyword(s):

Wind Tunnel ◽

Wind Turbine ◽

Lift Coefficient ◽

Turbine Blades ◽

Aerodynamic Characteristics ◽

Wind Turbine Blades ◽

High Lift ◽

Minimum Drag ◽

Stall Angle ◽

High Reynolds

High lift and low drag are desirable for wind turbine blade airfoils. The performance of a high lift airfoil at high Reynolds number (Re) for large wind turbine blades is different from that at low Re number for small wind turbine blades. This paper investigates the performance of a high lift airfoil DU93-W-210 at high Re number in low Re number flows through wind tunnel testing. A series of low speed wind tunnel tests were conducted in a subsonic low turbulence closed return wind tunnel at the Re number from 2×105to 5×105. The results show that the maximum lift, minimum drag and stall angle differ at different Re numbers. Prior to the onset of stall, the lift coefficient increases linearly and the slope of the lift coefficient curve is larger at a higher Re number, the drag coefficient goes up gradually as angle of attack increases for these low Re numbers, meanwhile the stall angle moves from 14° to 12° while the Re number changes from 2×105to 5×105.

Download Full-text

Effects of Leading-Edge Protection Tape on Wind Turbine Blade Performance

Wind Engineering ◽

10.1260/0309-524x.36.5.525 ◽

2012 ◽

Vol 36 (5) ◽

pp. 525-534 ◽

Cited By ~ 22

Author(s):

Agrim Sareen ◽

Chinmay A. Sapre ◽

Michael S. Selig

Keyword(s):

Wind Turbine ◽

Turbine Blades ◽

Leading Edge ◽

Reynolds Numbers ◽

Lower Surface ◽

Wind Turbine Blades ◽

Potential Benefits ◽

Wind Turbine Airfoil ◽

Turbine Airfoils ◽

The Impact

This paper presents results of a study to investigate the impact of using wind protection tape (WPT) to protect the leading edge of wind turbine airfoils from erosion. The tests were conducted on the DU 96-W-180 wind turbine airfoil at three Reynolds numbers between 1 and 1.85 million and angles of attack spanning the low drag range of the airfoil. Tests were run by varying the chordwise extent of the wind protection tape on the upper and lower surface in order to determine the relative impact of each configuration on the aerodynamics of the airfoil. The objective was to assess the performance losses due to the wind protection tape and compare them with losses due to leading-edge erosion in order to determine the potential benefits of using such tape to protect wind turbine blades. Results showed that the application of wind protection tape caused a drag increase of 5–15% for the various configurations tested and was significantly less detrimental to airfoil performance than leading edge erosion that could otherwise occur.

Download Full-text

Testing Rotating Horizontal Axis Wind Turbine Blade Designs in a Laboratory Wind Tunnel

Volume 5: Industrial and Cogeneration; Microturbines and Small Turbomachinery; Oil and Gas Applications; Wind Turbine Technology ◽

10.1115/gt2010-23575 ◽

2010 ◽

Cited By ~ 1

Author(s):

Kenneth W. Van Treuren ◽

Jason R. Gregg

Keyword(s):

Surface Roughness ◽

Wind Tunnel ◽

Wind Turbine ◽

Turbine Blade ◽

Turbine Blades ◽

Reynolds Numbers ◽

Full Scale ◽

Wind Turbine Blade ◽

Wind Tunnel Testing ◽

Wind Turbine Blades

The importance of renewable and alternative energy is rapidly gaining attention. A national goal of replacing 20% of the United States electricity generation with wind power by 2030 has been proposed but such an ambitious goal is dependent on many parameters. Improved aerodynamic performance of wind turbine blades is one parameter necessary to achieve this goal. Blade testing is traditionally done using 2D airfoils in a laboratory wind tunnel, developing the lift and drag coefficients, and then using this data to predict wind turbine blade performance. Dimensional analysis has been used successfully in design of rotating machinery such as pumps, developing a series of dimensionless pump parameters with which to scale a particular pump design to a larger or small size. These parameters lead to similarity or affinity laws which relate any two homologous states for two pumps that are geometrically and dynamically similar. Affinity laws could be applied to wind turbines however the conditions tested in the wind tunnel do not match what would be expected in a full scale wind machine. As with pumps, the laws would apply only if the model and full scale wind turbine would operate at identical Reynolds numbers and are exactly similar (i.e. relative surface roughness and tip conditions). Reynolds numbers in the model tests are smaller than those achieved by the actual wind turbines while the surface roughness of the model is generally larger. This leads to the need for empirical equations to predict performance. This paper examines current wind tunnel testing and the problems with scaling wind turbine blades. It also outlines a methodology to test 3-D model wind turbine blades in a wind tunnel. Blades are designed and manufactured according to existing criteria, mounted to a generator, and their performance is then tested in the wind tunnel. Challenges with wind tunnel testing as well as extrapolation of the wind tunnel data to actual applications will be addressed.

Download Full-text

Bio-inspired Leading-Edge Tubercles to Improve Fatigue Life in Horizontal Axis Wind Turbine Blades

35th Wind Energy Symposium ◽

10.2514/6.2017-1381 ◽

2017 ◽

Cited By ~ 5

Author(s):

Bing Feng Ng ◽

Tze How D. New ◽

Rafael Palacios

Keyword(s):

Fatigue Life ◽

Wind Turbine ◽

Turbine Blades ◽

Leading Edge ◽

Horizontal Axis ◽

Wind Turbine Blades ◽

Horizontal Axis Wind Turbine ◽

Improve Fatigue

Download Full-text

Leading edge erosion of wind turbine blades: Understanding, prevention and protection

Renewable Energy ◽

10.1016/j.renene.2021.01.044 ◽

2021 ◽

Vol 169 ◽

pp. 953-969

Author(s):

Leon Mishnaevsky ◽

Charlotte Bay Hasager ◽

Christian Bak ◽

Anna-Maria Tilg ◽

Jakob I. Bech ◽

...

Keyword(s):

Wind Turbine ◽

Turbine Blades ◽

Leading Edge ◽

Wind Turbine Blades

Download Full-text

Review of Icing Effects on Wind Turbine in Cold Regions

E3S Web of Conferences ◽

10.1051/e3sconf/20187201007 ◽

2018 ◽

Vol 72 ◽

pp. 01007 ◽

Cited By ~ 2

Author(s):

Faizan Afzal ◽

Muhammad S. Virk

Keyword(s):

Wind Turbine ◽

Structural Integrity ◽

Turbine Blades ◽

Leading Edge ◽

Added Mass ◽

Cold Climate ◽

Ice Accretion ◽

Wind Turbine Blades ◽

Turbine Performance ◽

Ice Shedding

This paper describes a brief overview of main issues related to atmospheric ice accretion on wind turbines installed in cold climate region. Icing has significant effects on wind turbine performance particularly from aerodynamic and structural integrity perspective, as ice accumulates mainly on the leading edge of the blades that change its aerodynamic profile shape and effects its structural dynamics due to added mass effects of ice. This research aims to provide an overview and develop further understanding of the effects of atmospheric ice accretion on wind turbine blades. One of the operational challenges of the wind turbine blade operation in icing condition is also to overcome the process of ice shedding, which may happen due to vibrations or bending of the blades. Ice shedding is dangerous phenomenon, hazardous for equipment and personnel in the immediate area.

Download Full-text

Brief communication: Nowcasting of precipitation for leading-edge-erosion-safe mode

Wind Energy Science ◽

10.5194/wes-5-977-2020 ◽

2020 ◽

Vol 5 (3) ◽

pp. 977-981 ◽

Cited By ~ 1

Author(s):

Anna-Maria Tilg ◽

Charlotte Bay Hasager ◽

Hans-Jürgen Kirtzel ◽

Poul Hummelshøj

Keyword(s):

Liquid Phase ◽

Wind Turbine ◽

Turbine Blades ◽

Leading Edge ◽

Wind Turbine Blades ◽

Spatio Temporal ◽

The Impact ◽

Theoretical Considerations ◽

Mode A ◽

Precipitation Events

Abstract. Leading-edge erosion (LEE) of wind turbine blades is caused by the impact of hydrometeors, which appear in a solid or liquid phase. A reduction in the wind turbine blades' tip speed during defined precipitation events can mitigate LEE. To apply such an erosion-safe mode, a precipitation nowcast is required. Theoretical considerations indicate that the time a raindrop needs to fall to the ground is sufficient to reduce the tip speed. Furthermore, it is described that a compact, vertically pointing radar that measures rain at different heights with a sufficiently high spatio-temporal resolution can nowcast rain for an erosion-safe mode.

Download Full-text