Numerical Study of Flow Field and Aerodynamic Performance of StraightBladed VAWT at Variable Tip Speed Ratios

摘要

This paper studies the relationship between unsteady flow features and instantaneous torque and powerperformance of straight bladed vertical axis wind turbine at variable tip speed ratios. The rotor unsteady flow fieldsimulation was carried out by using computational fluid dynamics method. The flow physics and the principle of changingflow filed acting on torque performance and power performance has been analyzed where the rotating rotor was the majorconcern. The results show that the flow feature alters from periodical blade dynamic stall vortexes generation,development and shedding at low tip speed ratio to cyclical formation, evolution and diffusion of blade wake flow withthe rising tip speed ratio. Both vortex shedding around the blade and interaction of blade wakes degrade the rotoraerodynamic performance. It is suggested that, to absorbing the maximum wind energy, delaying the blade vortexshedding and reducing the range of blade wake evolution and diffusion should be included in the rotor aerodynamicdesign.