Performance of SB-VAWT using a modified double multiple streamtube model

Abstract

The present study introduces a new relation to evaluate the equilibrium induced air velocity in the mid plane between the upstream and downstream rotor zones to give a good improvement in prediction of the maximum power coefficient. The relation is derived as a function of both interference factor in upwind and downwind rotor zones determined using classical DMST model. The root-finding algorithm is used to obtain the interference factor both in upwind and downwind zones of the turbine at each streamtube. The comparison between the numerical results and the experimental data of 5-m, 17-m, and 34-m Darrieus VAWTs shows that the use of the introduced relation gives a sensible improvement in the prediction of maximum value for turbine power coefficient. A theoretical study is presented based on the use of well documented symmetrical NACA0012 turbine blade profile. The effect of wind speed and rotor solidity on maximum power coefficient and corresponding optimal speed ratio on the turbine rotor is evaluated in order to determine an improved aerodynamic configuration for a given application.