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The influence on energy conversion and induction from large blade deflections

Abstract

Flexible 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)
Authors:
Aagaard Madsen, H; Rasmussen, F [1] 
  1. Risoe National Lab., Roskilde (Denmark)
Publication Date:
Mar 01, 1999
Product Type:
Conference
Report Number:
RISO-R-1114(EN); CONF-990314-
Reference Number:
SCA: 170602; PA: DK-99:001425; EDB-99:087323; SN: 99002098331
Resource Relation:
Conference: EWEC`99. European wind energy conference, Nice (France), 1-5 Mar 1999; Other Information: PBD: Mar 1999; Related Information: Is Part Of Contributions from the Department of Wind Energy and Atmospheric Physics to EWEC `99 in Nice, France; Larsen, Gunnar C.; Westermann, Kirsten; Noergaard, Per [eds.]; PB: 256 p.
Subject:
17 WIND ENERGY; WIND TURBINES; TURBINE BLADES; AERODYNAMICS; ROTORS; VELOCITY; FLEXIBILITY; CONICAL CONFIGURATION; POWER COEFFICIENT
OSTI ID:
679643
Research Organizations:
Risoe National Lab., Roskilde (Denmark). Wind Energy and Atmospheric Physics Dept.
Country of Origin:
Denmark
Language:
English
Other Identifying Numbers:
Other: ON: DE99747779; CNN: Contract ENS-1363/98-0005; ISBN 87-550-2542-0; TRN: DK9901425
Availability:
OSTI as DE99747779
Submitting Site:
DK
Size:
pp. 209-212
Announcement Date:
Oct 15, 1999

Citation Formats

Aagaard Madsen, H, and Rasmussen, F. The influence on energy conversion and induction from large blade deflections. Denmark: N. p., 1999. Web.
Aagaard Madsen, H, & Rasmussen, F. The influence on energy conversion and induction from large blade deflections. Denmark.
Aagaard Madsen, H, and Rasmussen, F. 1999. "The influence on energy conversion and induction from large blade deflections." Denmark.
@misc{etde_679643,
title = {The influence on energy conversion and induction from large blade deflections}
author = {Aagaard Madsen, H, and Rasmussen, F}
abstractNote = {Flexible 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)}
place = {Denmark}
year = {1999}
month = {Mar}
}