Topic
Blade pitch
About: Blade pitch is a research topic. Over the lifetime, 5321 publications have been published within this topic receiving 63134 citations.
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13 Aug 1999
TL;DR: In this article, the pitch of at least one blade of a wind turbine relative to a wind direction parallel to a longitudinal main shaft of the wind turbine is adjusted by a motor.
Abstract: The present invention relates to a method and a mechanism for adjusting/controlling the pitch of at least one blade (4) of a wind turbine relative to a wind direction parallel (11) to a longitudinal main shaft (1) of the wind turbine, the mechanism comprising a motor for rotating drive wheels (20, 21) in the angle gear around a longitudinal blade shaft (12) via drive wheels of an angle gear The invention also relates to a method and a mechanism for stopping the complete turning of a main shaft of a wind turbine comprising a motor to rotate a drive pinion in an angle gear via a drive wheel, the angle gear being meant to pitch at least one blade around a longitudinal axis
46 citations
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23 May 2005TL;DR: In this paper, a three-bladed Gamesa G58 wind turbine with a rotor diameter of 58 m and a tower height of 53.5 m was evaluated using 152 microphones mounted on a horizontal wooden platform (15 by 18 m 2 ).
Abstract: Acoustic array measurements were performed on a three-bladed GAMESA G58 wind turbine with a rotor diameter of 58 m and a tower height of 53.5 m. The goal was to characterize the noise sources on this turbine, and to verify whether aerodynamic noise from the blades is dominant. In order to assess the effect of blade roughness, one blade was cleaned, one blade was tripped, and one blade was left untreated. The acoustic array consisted of 152 microphones mounted on a horizontal wooden platform (15 by 18 m 2 ), which was positioned about 58 m upwind from the rotor. In parallel to the acoustic measurements, a number of turbine parameters were monitored, such as wind speed, power, turbine orientation, RPM, and blade pitch angle. In total more than 100 measurements were taken at wind speeds between 6 and 10 m/s. Two array processing methods were used to characterise the noise from the turbine. First, the noise sources in the rotor plane were localised using conventional beamforming. These results clearly show that, besides a minor source at the rotor hub, practically all noise (radiated to the ground) is produced during the downward movement of the blades. The noise is produced by the outer part of the blades (but not by the very tip), and blade noise levels scale with the 5 th power of the local flow speed. The second processing method employed rotating scan planes to localise the noise sources on the individual blades. It turns out that the tripped blade is significantly noisier than the clean and untreated blades, which is a strong indication of trailing edge noise (rather than inflow turbulence noise). The similar noise levels for the clean and untreated blades suggest that the untreated blade was aerodynamically clean.
45 citations
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TL;DR: In this article, the Triple Spar floater, a hybrid between a spar buoy and a semi submersible tri-floater, is tested with active blade pitch control.
45 citations
01 Mar 1982
TL;DR: The results of these studies indicate that a fuel saving of 15 to 30 percent may be realized by the use of an advanced high-speed turboprop (Prop-Fan) compared to aircraft equipped with high bypass turbofan engines of equivalent technology as discussed by the authors.
Abstract: The increased emphasis of fuel conservation in the world and the rapid increase in the cost of jet fuel has stimulated a series of studies of both conventional and unconventional propulsion systems for commercial aircraft. The results of these studies indicate that a fuel saving of 15 to 30 percent may be realized by the use of an advanced high-speed turboprop (Prop-Fan) compared to aircraft equipped with high bypass turbofan engines of equivalent technology. The Prop-Fan propulsion system is being investigated as part of the NASA Aircraft Energy Efficient Program. This effort includes the wind tunnel testing of a series of 8 and 10-blade Prop-Fan models incorporate swept blades. Test results indicate efficiency levels near the goal of 80 percent at Mach 0.8 cruise and an altitude of 10.67 km (35,000 ft). Each successive swept model has shown improved efficiency relative to the straight blade model. The fourth model, with 45 deg swept blades reported herein, shows a net efficiency of 78.2 at the design point with a power loading of 301 kW/sq meter and a tip speed of 243.8 m/sec (800 ft/sec.).
45 citations