Experimental flow analysis of vertical axis turbine for power generation in open channel system

Abstract

In this experimental study, flow structure over a three bladed vertical axis Darrieus turbine is investigated experimentally for Reynold Number, Re=9000 in an open channel. Rigidity ratio (σ), angle of attack, optimum values of blade chord length (CL), turbine radius (R) and height of turbine blades (H) are used as approximately 1.1 and α=-2°, CL=5 cm, R=13.75 cm and H=20 cm, respectively. According to the values, ¼ scale model of a vertical axis Darrieus turbine has been used in order to perform experimental flow analysis. In experimental flow analysis, two different azimuth angles, θ=270° and θ=240° are used to examine the flow characteristics in the Particle İmage Velocimetry (PIV) experiments. As a result of the experiments, time averaged velocity vectors , averaged streamlines , and averaged vortex fields , are obtained and interpreted time averaged velocity vectors , averaged streamlines , and averaged vortex fields , changes with the turbine blade positions. As a result, it is seen that turbine azimuthal angle affetcs the flow structure and streamline focal points, positive and negative vortex are formed in the flow region behind the turbine. Only one focal point at θ=240° is occurred while two focal points and one stagnation point are occurred at the angle of θ=270°.