Design and Analysis of the Aerodynamic Components for a Kilowatt Scale VAWT Optimized for Low Altitude Implementation in Remote Rural Villages

Abstract

The ideal operating conditions for traditional horizontal axis wind turbines (HAWTs) are generally described by high velocity, steady winds, and undisturbed, laminar air flow. In the direct vicinity of populated areas, these conditions can only be achieved at altitudes significantly above or beyond the built-up area, typically twice the height of the tallest surrounding obstruction. The cost of tower material and transmission lines makes placing turbines at optimal operating heights cost-prohibitive in low-income, remote villages. Though not ideal for HAWT operation, the wind close to the earth’s surface and in proximity of residences can be utilized with an appropriately designed vertical axis wind turbine (VAWT). These turbines, while having a lower theoretical maximum efficiency, can survive and utilize the turbulent multidirectional winds in this operating region while still providing usable power. This paper highlights the design and analysis work performed by the authors to increase the aerodynamic efficiency of a unique and patented VAWT design in order to optimize it for implementation in remote rural villages. The final product is a kW capacity VAWT of unique geometry based on the previous successful testing of a 100W prototype. Specifically, the authors explored the aerodynamic effects of varying the geometry of the radial arms and center hubs of the turbine using CFD and wind tunnel testing. The design goal was to develop arms with aerodynamic properties that complemented the function of the blades at the appropriate phases of a single revolution. While the previous prototype focused mainly on minimizing drag, this effort sought to design an arm profile that develops high drag in one airflow direction and minimizes drag in the opposite direction. Implementation of these results was realized in a fully functioning drag VAWT. Furthermore, the system was designed to keep the turbine affordable for remote populations with limited resources. This data is compared to theoretical performance calculations, existing wind turbine designs, and against predictions made using scaling factors on preexisting data from the smaller prototype.