1,721,075 research outputs found
Ultimate Loads of Upstream and Downstream Turbines in the Presence of Wake Steering-Based Wind Farm Control: Preliminary Analysis and Quantification
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Moriwaki divisors and the augmented base loci of divisors on the moduli space of curves
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An ongoing research activity on the effects of wind farm controls on the design of wind turbines
Full text linkStudying and Optimizing the Take-Off Performance of Three-Surface Aircraft
Full text linkIn the quest for making aircraft more energy-efficient, configuration, and primarily the arrangement and quality of aerodynamic surfaces, play a relevant role. In a previous comparative study by the authors, it was shown how to obtain a significant increase in cruise performance by adopting a three-surface configuration instead of a classical pure back-tailed design. In this paper, an analysis of the same configurations in take-off is carried out, to assess through a fair comparison the potential effect of a three-surface one especially on take-off distance. Take-off is mathematically described by means of a sound analytic approach. Take-off distance is computed for a baseline two-surface aircraft, and in a later stage on a three-surface one. In addition to exploring the performance, a numerical optimization is also deployed, so as to find the best use of both configurations analyzed (i.e., baseline and three-surface) in take-off, and the corresponding top performance. The quality of the optimum, as well as the practical realization of a control link between the yoke and both control surfaces in the three-surface configuration, are analyzed in depth. The paper describes the advantage which can be attained by selecting a three-surface configuration, and proposes some remarks concerning the practical implementation of the maneuver to actually capture an optimal performance
Effectiveness of dynamic induction control strategies on the wake of a wind turbine
Full text linkDynamic Induction Control (DIC) has been recently proposed as means for enhancing wake recovery and, in turn, for increasing the overall produced power. A faster wake recovery is triggered by a Periodic Collective Motion (PCM), following a single sine function (S-PCM), or by a combination of Gaussian functions (G-PCM). Both techniques are associated with power gains in simple two- or three-turbine farms, but entail an increase in machine loading. A technique named the Helix approach generates a dynamic induction through a thrust that varies in direction but not in magnitude, reducing the tower loading. This work aims to analyse the impact of bluff bodies, such as nacelle and tower on the performances of PCD techniques, and to quantify the DIC impact on the loads. A 5 MW reference wind turbine is used for the model, implemented in OpenFAST and SOWFA to perform large-eddy simulations (LES). The results obtained at a distance of 3D downstream, show less evidence of the bluff bodies using the PCM than the baseline, as an effect of the increased in-wake mixing. In a two-turbine wind farm with a separation of 3D between turbines, this effect leads to an increment in the overall power output of the farm, despite the presence of the tower and nacelle. The blockage itself does not seem to hamper the effectiveness of DIC. In both cases, DIC is responsible for an increment of about 7% in the overall power output
System and method for detecting misalignments in the pitch of one or more blades of a wind turbine
No full textThe present invention relates to a system (1) for detecting misalignments in the pitch of one or more blades (104) of a rotor (103) of a wind turbine (100) during its operation, comprising: - one or more fixed sensors (2), associated with a fixed portion of the wind turbine (100) comprising a pylon (101) extending in height along a fixed axis x perpendicular to a fixed plane defined by fixed axes y-z, and capable of detecting a momentum or angular acceleration or acceleration along said fixed axes y and/or z and providing representative signals thereof; - a control unit (3) configured to receive as input signals provided by said fixed sensors (2), calculate the frequency spectrum thereof, and determine the presence of a misalignment in the pitch of at least one of the blades (104) if the frequency spectrum of at least one of said signals from said fixed sensors (2) exhibits a peak at the rotor rotation frequency (fr). The present invention further relates to a method for detecting misalignments in the pitch of one or more blades (104) of a rotor (103) of a wind turbine (100) during its operation
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