A new approach for optimization of Vertical Axis Wind Turbines

Abstract

A new approach has been developed for the optimization of Vertical Axis Wind Turbines (VAWTs). The approach is derived from double multiple streamtube theory (DMST) and adopts the concept of “Representative streamtube” wherein the entire aerodynamic property of the VAWT is assumed to be represented by a single streamtube occupying a specific azimuthal location. Five input parameters namely; power, wind velocity, aspect ratio, air viscosity and air density and six output parameters that are minimally required for the construction of a straight bladed, constant pitch VAWT are considered in the study. The discrete data of lift and drag coefficients pertaining to specific values of Reynolds number and angle of attack are arranged in the order of decreasing lift to drag ratio and starting with the first set of coefficients, a check is made if it is eligible to become Representative streamtube for the particular problem. The check is done through a tri-directional “Demand Factor” test that seeks the compatibility of Reynolds number and angle of attack values of the aerofoil data under consideration. The first set which gains the eligibility to become “Representative streamtube” marks the solution for the particular problem.