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Title:Wind tunnel study of wind farms with alternating 2- and 3-bladed wind turbines
Author(s):Hayat, Imran
Advisor(s):Chamorro, Leonardo P.
Department / Program:Aerospace Engineering
Discipline:Aerospace Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Two-bladed turbine
Power optimization
Wind farm
Abstract:With offshore wind farms gaining substantial momentum in recent years, 2-bladed turbines (2BT) are increasingly becoming a viable alternative to 3-bladed counterparts (3BT). In this wind tunnel study, model wind farms with alternating rows of 3BT and 2BT were explored for potential benefits associated with enhanced momentum available within the arrays and reduced costs due to the reduction of blades. Two arrays of aligned turbines with streamwise separation of five and ten rotor diameter d (Sx = Δx/d =5 and 10) were operated in a turbulent boundary layer flow. They shared the same transverse turbine spacing of Sy = Δy/d =2.5. High-resolution velocity measurements were made with hotwire anemometry at various locations in the wake and the power output of turbines was measured simultaneously. Comparison of the flow between an array with only 3BT and that with alternating 2BT and 3BT shows enhanced mean velocity and reduced turbulence levels for the latter in Sx = 5 case. The pre-multiplied spectra of the flow at selected locations within the wind farm suggest that large energetic structures at top-tip and hub height are dampened by 2BT, with the potential to reduce turbulent loading on downwind turbines. Although the reduced mixing at top tip height behind 2BT causes the momentum recovery rate to diminish, the available momentum at downstream turbine is still higher than corresponding 3BT in the Sx = 5 case. Overall performance gain from marginally enhanced power statistics of 3BT operating in the wake of 2BT is offset by the diminished performance of 2BT inside the farm, resulting in comparable performance between the two configurations.
Issue Date:2017-12-11
Rights Information:Copyright 2017 Imran Hayat
Date Available in IDEALS:2018-03-13
Date Deposited:2017-12

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