Print Email Facebook Twitter Self-starting of a small urban Darrieus rotor Title Self-starting of a small urban Darrieus rotor: Strategies to boost performance in low-Reynolds-number flows Author Bos, R. Contributor van Bussel, G.J.W. (mentor) Timmer, W.A. (mentor) Geurts, B.M. (mentor) Faculty Aerospace Engineering Department Wind Energy Programme Sustainable Energy Technology Date 2012-11-20 Abstract Like many vertical-axis wind turbines (vawts) of the Darrieus type, Turby fails to achieve a fully passive start-up. Experiments indicate that there is a band of negative torque—often referred to as dead band in literature—somewhere in the tip speed range 0.5 B l B 1.6. The reason behind this is that, unfortunately, the power coefficient obtained at the rated wind speed is all but constant. The combination of low wind speeds and the small scale of the device leads to very low Reynolds numbers; well in the order of < 105. The lift production and stall behavior of the airfoils aggravates in these conditions, with low starting torque as a result. The design case revolved around Turby – a small 1.6 kW, 2.20 m diameter vawt with a projected cut-in wind speed of 3 m/s. The purpose of this master thesis is to investigate the cause of the poor start-up performance and to find possible solutions for the problem. This eventually led to a design proposal. Subject Windenergy To reference this document use: http://resolver.tudelft.nl/uuid:5a3585c4-7083-432d-88de-8c8dc9a3d948 Part of collection Student theses Document type master thesis Rights (c) 2012 Rene Bos Files PDF Rene Bos r2.pdf 49.37 MB Close viewer /islandora/object/uuid:5a3585c4-7083-432d-88de-8c8dc9a3d948/datastream/OBJ/view