Blade pitch

About: Blade pitch is a research topic. Over the lifetime, 5321 publications have been published within this topic receiving 63134 citations.

Method and apparatus for wind turbine rotor load control based on shaft radial displacement

Abstract: Vertical and horizontal wind shears, yaw misalignment and/or turbulence act together to produce asymmetric loading across a wind turbine rotor. The resultant load produces bending moments in the blades that are reacted through the hub and subsequently to the main shaft. As a result, the main shaft may be radially displaced from its at rest positions. The amount of radial displacement is measured using two or more sensors. The output signals from the sensors are used to determine the magnitude and/or the orientation of the resultant rotor load. This information is used to affect the blade pitch change or other action with similar system effect to reduce the asymmetric load and thereby reduce fatigue and loading on various turbine components.

Method and apparatus for wind turbine rotor load control

Abstract: Vertical and horizontal wind shears, yaw misalignment and/or turbulence act together to produce asymmetric loading across a wind turbine rotor. The resultant load produces bending moments in the blades that are reacted through the hub and subsequently to the low-speed shaft. As a result, the main shaft and main shaft flange are displaced from their at rest or non-aerodynamic load positions. The amount of shaft flange displacement is measured using one or more sensors. The output signals from the sensors are used to determine the magnitude and/or the orientation of the resultant rotor load. This information is used to effect the blade pitch change needed to reduce the load and thereby reduce fatigue and loading on various turbine components.

Aerodynamic interaction between propellers and wings

Abstract: A combined computational/experimental investigation has been conducted to determine the time-averaged interactive performance of a propeller and wing in tractor configuration at Mach 0.1 and Re=470,000, based on a wind tunnel model wing chord of 8 in. Wing angle-of-attack was varied from 0 to +13 deg, and propeller advance ratio ranged from 2.4 (windmilling) to 1.1 (maximum power). Both a semiempirical model and a vortex lattice simulation were used in the computational analysis. Good agreement has been obtained between theory and experiment.

Individual Blade Pitch Control for the Controls Advanced Research Turbine "CART…

Abstract: Pitching the individual blades of a horizontal-axis wind turbine allows control of asymmetric aerodynamic loads, which in turn influences structural loads in the nonrotating frame such as tower side-side bending. These loads are not easily controlled by traditional collective pitch algorithms. This paper presents the design of individual pitch control systems for implementation on the Controls Advanced Research Turbine (CART) in Colorado to verify controller performance for load attenuation. The control designs are based on linear time-periodic state-space models of the turbine and use optimal control methods for gain calculation. Comparisons are made between new individual pitch, new collective pitch, and baseline controller performance in both above rated and below rated wind conditions. Results from simulations show the potential of individual pitch to reduce tower side-side fatigue damage in above rated wind speeds (by 70% compared to baseline control) but with no improvement over collective pitch in below rated wind speeds. Fatigue load reductions in tower fore-aft, shaft torsion, and blade flap are also observed. From 13h of field testing, both collective and individual pitch controllers achieve a reduction in fatigue damage. However, the superior performance of individual pitch control observed in simulation was not verified by the field test results.