Featured Research

from universities, journals, and other organizations

Experimental blade research

Date:
February 4, 2011
Source:
Risø National Laboratory for Sustainable Energy
Summary:
A 34-meter long blade has been subjected to every form of twisting, turning, pulling, wearing and tearing imaginable. This has led to the development of a completely new test method for improving blade structures and blade design, which combines the loads acting on the blade.

The 34 meter long blade hanging at Risø DTU.
Credit: Image courtesy of Risø National Laboratory for Sustainable Energy

A 34-metre long blade from SSP-Technology A/S is currently freely suspended inside Risø's Experimental Research Facility for Blade Structure, and since 2008 the blade has been subjected to every form of twisting, turning, pulling, wearing and tearing imaginable. This has led to the development of a completely new test method for improving blade structures and blade design, which combines the loads acting on the blade. The method is already in use in the industry.

Wind turbine manufacturers currently use special-designed wind tunnels, high-calculation capacity computer programs and engineers who, almost before the blade has been designed, are able to predict how it will behave down to the smallest detail. However, testing the finished full-scale blades in the most realistic way is still essential in order to develop the most reliable and cost-efficient wind turbine blades.

"In 2008, the research area 'Experimental Blade Research' received a DKK 3 million grant from EUDP for Phase 1 and has now received a total funding from EUDP of DKK 10 million for Phase 2, which will boost the entire research area considerably. Already in its first phase, the Risø-based project has generated excellent results, and ten external partners have chosen to join the project, including eight from the Danish wind turbine industry," says Find Mølholt Jensen who is heading the project.

The overall project objective is to jointly develop an experimental platform for testing the blades of the future as well as to develop new methods that provide designers with reliable tools for achieving the best possible results.

Combined loading

Until now, loads were applied to the blades by casting a clamp around the blade and then subject the clamp to vertical and horizontal pulling. However, this does not reproduce the actual loads to which the blade is subjected when in operation with enormous pulling and distortion on both the edge and the flap. Loads that could not be taken into consideration with the old test method, but with the newly developed method loads can now be applied to the blade in a far more realistic way.

"The new test method is based on more realistic loads being applied to the blade where we rotate/turn the blade and subsequently apply a combined pull to the edge and the flap. In this way, loads are also applied to, e.g. the glued joint between the shells, which is one of the known critical areas in the blade structure," Find Mølholt Jensen explains.

In operation, the wind turbine blade may be subject to distortion, but with the old test method, this blade deformation was prevented by the clamp as it encircled the blade, preventing transverse shear. To avoid using this blade-fixing clamp, the new method involves mounting steel anchor plates directly on the blade, allowing deformation and tilting of the blade when subjected to pulls.

Phase 1 solutions already reviewed

In Risø's Experimental Research Facility for Blade Structure, the 34-metre long blade is mounted on a base and load is applied by pulling the blade towards the floor using forces of up to approx. 10 tons. The method is already in use in the wind turbine industry.

The project also involved examining how to relieve some of the loading points on the blade which the new method has revealed. One of the tests involved making a simple coupling of two blade panels using a 'string'. This coupling, which has been developed at Risø, has proven efficient in preventing out-of-plane deformation of the panels. And by preventing blade deformation, the blade's life can be increased considerably. In Phase 2, more stress-relief methods will be tested.

New measuring techniques

A natural element of the development of the new experimental test method was the development of new measuring methods. Find Mølholt Jensen explains:

"During the project, we developed two new measuring methods. The first involves using an optical digital system to accurately determine even the slightest blade deformation. By making an area of randomly placed spots, you can subsequently compare the images from the two cameras filming the blade during load testing and see whether the spots have been displaced and in which direction. The other method uses acoustic emission to measure deformation and can thus help prevent fatal blade cracks during the actual test."

The optical digital method is also being used in the industry where several Phase 2 partners are either already using it or are planning to integrate the system in the near future. Risø's Materials Research Division has played a critical role in developing the new measuring methods, both in terms of knowledge and resources.

Ten external partners and unique knowledge from the aircraft and helicopter industry Vestas, LM Windpower and SSP Technology A/S were already involved in Phase 1, but no less than seven new stakeholders have chosen to participate in Phase 2 of the project, giving a total of ten external partners. The new partners are Dong, DNV, Blaest, Hexcel, Baumer, DLR and Swerea Sicomp.

Two of the new partners, DLR and Swerea Sicomp, are leading research institutions from Germany and Sweden, respectively, with core competencies within other composite structures than wind turbine blades, i.e. aircraft and helicopter wings.


Story Source:

The above story is based on materials provided by Risø National Laboratory for Sustainable Energy. Note: Materials may be edited for content and length.


Cite This Page:

Risø National Laboratory for Sustainable Energy. "Experimental blade research." ScienceDaily. ScienceDaily, 4 February 2011. <www.sciencedaily.com/releases/2011/02/110204091249.htm>.
Risø National Laboratory for Sustainable Energy. (2011, February 4). Experimental blade research. ScienceDaily. Retrieved April 17, 2014 from www.sciencedaily.com/releases/2011/02/110204091249.htm
Risø National Laboratory for Sustainable Energy. "Experimental blade research." ScienceDaily. www.sciencedaily.com/releases/2011/02/110204091249.htm (accessed April 17, 2014).

Share This



More Matter & Energy News

Thursday, April 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

German Researchers Crack Samsung's Fingerprint Scanner

German Researchers Crack Samsung's Fingerprint Scanner

Newsy (Apr. 16, 2014) — German researchers have used a fake fingerprint made from glue to bypass the fingerprint security system on Samsung's new Galaxy S5 smartphone. Video provided by Newsy
Powered by NewsLook.com
Porsche CEO Says Supercar Is Not Dead: Cue the Spyder 918

Porsche CEO Says Supercar Is Not Dead: Cue the Spyder 918

TheStreet (Apr. 16, 2014) — The Porsche Spyder 918 proves that, in an automotive world obsessed with fuel efficiency, the supercar is not dead. Porsche North America CEO Detlev von Platen attributes the brand's consistent sales growth -- 21% in 2013 -- with an investment in new technology and expanded performance dynamics. The hybrid Spyder 918 has 887 horsepower and 944 lb-ft of torque, but it can run 18 miles on just an electric charge. The $845,000 vehicle is not a consumer-targeted vehicle but a brand statement. Video provided by TheStreet
Powered by NewsLook.com
Industry's Optimism Shines At New York Auto Show

Industry's Optimism Shines At New York Auto Show

Newsy (Apr. 16, 2014) — After seeing auto sales grow last month, there's plenty for the industry to celebrate as it rolls out its newest designs. Video provided by Newsy
Powered by NewsLook.com
Ford Mustang Fetes Its 50th Atop Empire State Building

Ford Mustang Fetes Its 50th Atop Empire State Building

AFP (Apr. 16, 2014) — Ford celebrated the 50th birthday of its beloved Mustang by displaying a new model of the convertible on top of the Empire State Building in New York. Duration: 00:28 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins