Flow separation on a high Reynolds number, high solidity vertical axis wind turbine with straight and canted blades and canted blades with fences

The aerodynamics of a high solidity vertical axis wind turbine was investigated through wind tunnel tests of a full size turbine operating at Reynolds numbers of Re ≥ 500,000 (where the power production has been shown to be Re independent). Flow visualization using light-weight tufts attached to the inner surface of a blade was used to gain insight on the operating aerodynamics, which is related to the measured power performance. The tufts proved to be an effective and simple technique to observe the flow characteristics on the large scales involved where other flow measurement techniques like particle image velocimetry or laser Doppler velocimetry would be challenging and expensive.