The Savonius rotor, a drag-based vertical-axis wind turbine, is characterized by its lower noise level, self-starting capability, design simplicity and lower installation and maintenance cost. Further, it can operate at low wind speed is independent of wind direction. Usage of the Savonius wind rotor is increasing worldwide to provide electricity without contributing to global warming and promoting small-scale energy production. However, its lower performance remains a major problem due to the high unproductive torque produced by the returning blade. One of the treatments for this issue is to develop a well-designed rotor blade profile, and in this regard, constant efforts are being made over the past few decades to play with various influential parameters to achieve the appropriate design configuration. Thus, it is imperative to develop a rotor blade under an optimization platform. In addition to using a standard semicircular blade, other blade adjustments have emerged over the past two decades to improve the Savonius rotor performance. Subsequently, additional methods such as numerical and optimization techniques can be to improve the rotor performance by developing an optimal rotor design.In this paper, an optimum blade profile is obtained by maximizing the power coefficient (CP) considering the overlap ratio (OR) as an optimization parameter by coupling computational fluid dynamics (CFD) simulation to the rotor blade profile developed through the simplex search method. The blade profile is symmetric about the x-axis, where half of the blade geometry is formed by a natural cubic spline curve using three points. Two end points are retained fixed, while x and y of the third point is taken as a variable in addition to OR in the simplex search process throughout its iteration using the MATLAB platform. In all the iterations, the blade profile is meshed by using ANSYS ICEM CFD platform. The rotor performance analysis is carried out by ANSYS Fluent using the shear-stress transport (SST) k-w turbulence model. The finite volume method (FVM) is used as a solver setup to solve the transient 2D flow around the rotor blade. The optimum blade profile is compared to a conventional semicircular blade profile over a wide range of tip speed ratio (TSR) to find the feasibility in practical application. The present study demonstrates the superior performance of the optimum blade profile showing 23% higher CPmax as compared to conventional semicircular blade profile at TSR = 0.8. Further, at OR = 0.154, the CP is found to be maximum. The velocity magnitude contours, total pressure and turbulence intensity contours are generated to analyse the effect of optimal design approach.

Overlap Ratio as the Design Variable for Maximizing the Efficiency of a Savonius Wind Rotor: An Optimization Approach

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.