Print Email Facebook Twitter Investigating the performance of wind farms with alternating tower heights Title Investigating the performance of wind farms with alternating tower heights Author Van Heerde, S. Contributor Tomas, J.M. (mentor) Pourquie, M.J.B.M. (mentor) De Roode, S.R. (mentor) Faculty Mechanical, Maritime and Materials Engineering Department Process and Energy Programme Fluid Mechanics Date 2015-10-08 Abstract Johnstone and Coleman (2012) were among the first to opt the idea of wind farms with mixed tower heights and predicted an increased power production due to the decrease of losses to TKE production from the mean kinetic energy balance. In the current study, the performance of infinite wind farms with alternating tower heights imposed by a neutrally stratified half-channel boundary layer is investigated. A LES approach is selected by using the existing LES code DALESURBAN. To model wind turbines, the non-uniform actuator disk model is selected and its implementation into DALESURBAN described. Three wind farm configurations are investigated and compared: a farm with only high turbines, a farm with tower heights alternating in row configuration and a farm with tower heights alternating in staggered configuration. When comparing the two alternating configurations, no significant difference in power production is found. For the farm with tower heights alternating in staggered configuration, the fluctuation of power production is found higher and the fatigue life expected shorter. When comparing the alternating configurations with the farm with only high turbines, an increased power production of 4% to 5% is found. However, the source for this increase is primarily the decrease of tower drag surface and not the result of decreased losses to TKE production as proposed by Johnstone and Coleman (2012). Furthermore, the fluctuation of the power production increases and the fatigue life of the high turbines is expected to decrease. As an undesirable side-effect, in the alternating configurations the fatigue life for the high turbines is found to be shorter than for the low turbines. Investigation of tower height alternation in the infinite wind farm gave results against its application. However, the effects of flow development along the wind farm are not taken into account. Therefore, it is recommended to perform future research on wind farms with tower height alternation within an inflow-outflow model description. Subject wind farmwind turbinetower heightmixed tower heightalternating tower heightDALESURBANLESinfinite wind farm To reference this document use: http://resolver.tudelft.nl/uuid:d631829e-4989-4730-8e05-d20079555b81 Part of collection Student theses Document type master thesis Rights (c) 2015 Van Heerde, S. Files PDF 20150921_final_thesis.pdf 9.74 MB Close viewer /islandora/object/uuid:d631829e-4989-4730-8e05-d20079555b81/datastream/OBJ/view