In-Situ Experiments to Estimate the Performance Characteristics of a Double-Step Helical-Bladed Hydrokinetic Turbine

With the rising level of greenhouse gas emissions and fuel prices, the hydrokinetic turbines have become increasingly popular for electricity generation in rural and remote areas teemed with small river streams. Such lift-based helical-bladed hydrokinetic turbines were invented over a decade ago, however, they could not find their wide application in commercial power generation. The present investigation deals with the in-situ experiments of a double-step three-bladed helical hydrokinetic turbine for possible electricity generation. Further, its performance is compared with that of a conventional single-step helical-bladed turbine. The main parameters that influence the performance of a helical-bladed hydro turbine are solidity ratio, blade wrap ratio, helix angle, blade profile and number of blades. In the present work, the helical NACA 0022 bladed turbines with solidity ratio of 0.20 and blade wrap ratio of 1.0 have been developed. The developed single and double-step configurations have been field-tested in the Brahmaputra river and their performance characteristics are estimated at different mechanical loading conditions using mechanical dynamometer.