Modeling analysis and experimental research on a combined-type vertical axis wind turbine

In order to overcome the inherent shortcomings of onefold airfoil vertical axis turbine, this paper presents a design combines a two-stage Savonius (S-type) rotor with a three-fan straight bladed Darrieus (H-type) rotor through an overrun clutch. This hybrid vertical axis turbine has lower self-starting wind speed and better conversion efficiency. The multi-stream tube model has been used to analyze and calculate the performance of the combined type straight-bladed vertical axis wind turbine (CT-SBVAWT). A prototype whose sweeping area is 2.15 m² is designed and manufactured and the Preliminary performance test is carried out. At the 10 m/s wind speed, the turbine can reliably self-start even when the load torque is 3.1 Nm. When the wind velocity change from 0-12 m/s, the experimental curve about output power vs. wind speed has the double features of both the drag-type vertical axis wind turbine and the lift-type vertical axis wind turbine, that is a good starting characteristics and better energy utilization at higher flow speeds.