%AAagaard Madsen, H
%ARasmussen, F [Risoe National Lab., Roskilde (Denmark)]
%D1999
%I; Risoe National Lab., Roskilde (Denmark). Wind Energy and Atmospheric Physics Dept.
%J
%K17 WIND ENERGY, WIND TURBINES, TURBINE BLADES, AERODYNAMICS, ROTORS, VELOCITY, FLEXIBILITY, CONICAL CONFIGURATION, POWER COEFFICIENT
%PMedium: ED; Size: pp. 209-212
%TThe influence on energy conversion and induction from large blade deflections
%XFlexible blades or coning means that the swept area is no longer a plane disc as assumed in the blade element momentum (BEM) theory. How is the induced flow field of the rotor influenced by such changes and what does this mean for the loading and energy conversion? This has been investigated by studying the flow through four different rotor geometries on basis of a numerical, axis-symmetric actuator disc model. Volume forces perpendicular to the local blade surface were applied and the converted power is the work performed by these forces. To simplify the comparisons, only a constant load distribution was used. The numerical results show that the shape of the rotor disc has considerable influence on the induction or axial velocity. The axial velocities vary with radial position in the case of constant loading where BEM theory gives constant velocities. There is considerable variation of the local power coefficient C{sub p,loc} even for constant loading. Locally, C{sub p,loc} can exceed the Betz limit. However, integrating C{sub p,loc} over the rotor plane, the total power coefficient for the different rotors are exactly the same. (au)
%0Conference
Denmark Other: ON: DE99747779; CNN: Contract ENS-1363/98-0005; ISBN 87-550-2542-0; TRN: DK9901425 DK English