The variable pitching of the blade has a great effect on the power extraction of the vertical axis wind turbine (VAWT). In the present study, a gear-linkage mechanism is incorporated into the design of the VAWT to achieve the passive variable pitching of the turbine blade, and the effect of the passive pitching amplitude and phase difference, on the power extraction performance, are analyzed by combining numerical analysis and experimental testing. The numerical results show that passive variable pitching can effectively improve the VAWT’s performance. The power extraction efficiencies of the turbine, with the optimized variable passive pitching blade, are 39.01, 25.83 and 15.78 times higher than those of the turbine with fixed blade, at the wind speeds of 3, 6 and 9 m/s, respectively. Further analysis of the vortex structure, around the turbine, reveals that variable passive pitching can suppress the vortex separated from the blade surface and weaken the dynamic interaction between the windward-separated vortex and leeward blade. Furthermore, the experimental test results, of the prototype with passive variable pitching and fixed blade, endorse the numerical conclusion viz. the average power of the prototype with variable pitching blade is 4.6 folds that of the prototype with fixed blade, under identical experimental conditions.

© The Author(s) 2022. Published by Oxford University Press.
2022
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