Straight-bladed vertical axis wind turbine rotor design guide based on aerodynamic performance and loading analysis

Abstract

Vertical axis wind turbines with straight blades are attractive for their relatively simple structure and aerodynamic performance. An efficient design methodology is required to enhance this resurging renewable energy technology. This paper aims to provide a robust design procedure built on an existing analytical approach to determine the optimum range of the design parameters for prototype construction. Identifying the proper range of design parameters can save significant time and resources in the initial turbine development stages. Here the double-multiple streamtube method has been utilized to analyze turbine aerodynamic performance. A parametric optimization has been performed for several design factors to maximize the turbine power coefficient and its operational range. The results show that the optimum value of the rotor solidity factor, blade aspect ratio, and rotor aspect ratio are in the range of 0.2 < σ < 0.6, 10 < μ < 20, and 0.5 < H/D < 2, respectively. Aerodynamic loading analysis has also been carried out, and the most severe stresses acting on the blades and supporting arms were determined. The most favorable bending stress distribution along the blade occurred when two supporting arms per blade were used at intermediate locations of 21% and 79% along the blade length. A comparative study of different supporting arm shapes demonstrated that utilizing aerodynamic profiles for turbine arms created the most acceptable aerodynamic response. A summary of design aspects addressed in this paper is presented in a useful summary flowchart.