Passive minimization of load fluctuations on downwind turbines

C. Kress, N. Chokani and R.S. Abhari

Renewable Energy, 2016, vol. 89, issue C, 543-551

Abstract: While tilting and coning of the rotor are well established on upwind turbines, this is not so for downwind turbines. Therefore, a detailed experimental assessment of the effects of rotor tilt and rotor cone on the fluctuations of torque and thrust on downwind turbines is conducted, and compared to upwind turbines. It is shown that on downwind turbines, the effects of tilting and coning are opposite. As the tilt angle is increased, the fluctuations decrease on downwind turbines. On the other hand, increasing the cone angle increases the fluctuations. While both tilting and coning increase the blade-tower clearance, thereby reducing the adverse effect of the tower wake, the impact of changing the tilt or cone angles must also be assessed in the context of changes in the radial migration of flow across the blade span. On downwind turbines coning enhances the radially outboard flow migration; the increased azimuthal variation of radial migration results in a degraded aerodynamic performance. However, tilted downwind turbines combine the benefits of increased tower-blade clearances with a reduced radial flow migration. Nevertheless, as coning improves yaw stability, downwind turbines with relatively large tilt angle and moderate cone angle are preferred.

Keywords: Downwind turbine; Rotor tilt; Rotor cone; Thrust variations; Torque fluctuations (search for similar items in EconPapers)
Date: 2016
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (4)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:89:y:2016:i:c:p:543-551

DOI: 10.1016/j.renene.2015.12.009

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