Sharma, RFlay, RImraan, Mustahib2013-05-082013https://hdl.handle.net/2292/20474Telescopic Blade Wind Turbine Systems offer great benefits to the wind industry and in particular to low speed wind site for potential development and enhancement. An inherent feature of a telescopic blade system is the discontinuity or step change in chord that exists between the fixed inner blade section, and the movable or telescopic outer blade section. This is its main distinctive feature when compared to a standard wind turbine blade, and it is therefore a major point of difference from an aerodynamic performance point of view as well. This thesis attempts to investigate the effect of the sudden change in chord of a Telescopic Blade Wind Turbine System, using a combination of experimental, analytical, and computational studies. In particular, it is aimed at studying the dynamics of the flow around the step change region and its influence on blade aerodynamics; at investigating the influence of the step change and telescopic blade parameters on the turbine performance and energy output; and at developing a correlation for the losses that arise from the step change region. Performance testing was carried out at model-scale in the wind tunnel, of a Telescopic Blade Wind Turbine System with two-stage telescopic blade s (i.e. blades with two sections of different chords), having chord ratios of 0.6 and 0.4, and for blade extensions ranging 0 – 40% (in length of the first section). The power coefficient Cp of the wind turbine was found to decrease with extension, with a 25% decrease in maximum Cp obtained for a 20% blade extension. This is attributed to additional losses arising from the step change in chord. It was hypothesised that the step change region induces vortex rollup in a manner similar to that which happens at the tip. Correlations developed to quantify losses arising from the step change in the chord of a telescopic blade are in good agreement with experimental data, and this would pave the way for improved performance predictions. Investigations into the aerodynamic performance of a single telescopic blade with a step change in chord were also carried out in the wind tunnel. From the surface static pressure measurements and flow visualisation studies, it was established that the sudden change in the blade chord causes an abrupt drop in pressure around the step region, which causes vortex roll, confirming the hypothesis drawn from performance testing. Energy output analyses reveal that the percentage increase in the annual energy output for the telescopic blade wind turbine system over the corresponding non-telescopic blade system could be as high as ~48% for a blade with 40% extension at a chord ratio of 0.6 in wind class 2. For the range of shape factors, chord ratios and blade extensions studied in this research, the reduction in annual energy output due to the step change in blade chord is found to be in the range of 15 to 1% for Wind Class 2 to 7 respectively.Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher.https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htmhttps://creativecommons.org/licenses/by-nc-sa/3.0/nz/ThesisCopyright: The Authorhttp://purl.org/eprint/accessRights/OpenAccessQ112903514