Analysis of vertical axis wind turbine power changing with rotating speed from vertical and horizontal flow fields
JI Wenju1,2, WANG Jianwen1,2, XUE Shuo2*, XIAO Chang2, GAO Zhiying1,2
1.Key Laboratory of Wind and Solar Power Energy Utilization Technology Ministry of Education and Inner Mongolia Construction, Hohhot, Inner Mongolia 010051, China; 2.College of Energy and Power Engineering, Inner Mongolia University of Technology, Hohhot, Inner Mongolia 010051, China
To further clarify the effect of the rotor′s rotating speed on the vertical axis wind turbine′s power output, taking a small vertical shaft wind turbine as the study object, based on the Fluent calculation software, using the SST k-ω turbulence model combining with sliding grid technology, and using the SIMPLE algorithm iteration and the second-order windward format, we calculated the vertical axis wind turbine in the unsteady state and obtained the wind turbine′s power output at different rotating speeds. Comparing the calculated with the experimental result, we confirmed the law of wind turbine′s power changing with a rotating speed. Wind turbine′s velocity field study gives the wake velocity contours of the longitudinal profile at different locations, and the low-speed section in the wake longitudinal profile velocity contours presents a vertical symmetry and horizontal asymmetry phenomenon. At the same time, by comparing the wind turbine′s wake flow field longitudinal profile velocity contours and the horizontal vorticity field contours at different rotating speeds, it is found that wind turbine has the maximum absorption wind energy and the minimum vorticity loss at a rated speed. And the cause of this phenomenon is analyzed. From the longitudinal flow field and the transverse flow field, we analyze the reason for wind turbine′s biggest power output at the rated speed,more clearly revealing the mecha-nism of wind turbine′s output power changing with the rotating speed. Research, from a dual angle of the longitudinal cross-section and the horizontal cross-section, shows the change of wind turbine′s flow field, which can provide the reference for the design of the vertical axis wind turbines and the aerodynamic performance improvement.
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