An Experimental Investigation on the Performance of Vertical Axis Wind Turbine in Steady Wind

Jonathan Mark Edwards, Louis Angelo Danao, Okeoghene Eboibi

Abstract


An experimental study was carried out into the performance of a wind tunnel scale vertical axis wind turbine (VAWT) under steady wind conditions. Wind speed tested was 7m/s, giving a Reynolds number of around 75,000. The power coefficient (CP) of the VAWT over a wide range of λ reveals a negative trough from λ = 1 up to λ = 3 with the lowest CP of -0.11 at λ = 2.4. Beyond λ = 3 CP rises to a maximum of 0.21 at λ* =4.0 after which it falls close to zero at λ = 5. This CP profile is typical of the scale of the VAWT tested where a negative trough is present mostly due to high zero-lift drag that hampers the ability of the rotor to generate positive torque at low λ and self-start. The negative trough is observed to slowly diminish as wind speeds, and consequently, Reynolds number increases.


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