Prince, Simon A.Badalamenti, CarmineGeorgiev, Dimitar2020-07-162020-07-162020-07-14Prince SA, Badalamenti C, Georgiev D. (2020) Experimental investigation of a variable geometry vertical axis wind turbine. Wind Engineering, Volume 45, Issie 4, 2021, pp. 904-9200309-524Xhttps://doi.org/10.1177/0309524X20935134https://dspace.lib.cranfield.ac.uk/handle/1826/15553An experimental study is presented on the performance of a vertical axis wind turbine with variable blade geometry of the design developed by Austin Farrah. This is experimentally compared with the performance of a correspondingly sized Bach-type Savonius turbine using the same electrical generator and measurement instrumentation in a wind tunnel. Experiments were performed for Reynolds numbers, based on blade chord, in the range 5 × 103 to 1 × 105, and for blade settings between −40° and +40o. The study shows that for the tip speed ratios that have been investigated, the Farrah vertical axis wind turbine design can only marginally outperform a corresponding two-bladed Bach-type Savonius turbine and then only when its blades are set to 40° pitch angle. The presence of a small inner cylinder, which rotates with the turbine, does not enhance its performance due to the fact that it is immersed in an extensive column of relatively static air.enAttribution-NonCommercial 4.0 Internationalhttp://creativecommons.org/licenses/by-nc/4.0/Vertical axis wind turbineFarrah turbineSavonius turbineaerodynamicsArticle