analysis of tower shadow effects and noise radiation from ...€¦ · are possible because the wind...
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![Page 1: Analysis of Tower Shadow Effects and Noise Radiation from ...€¦ · are possible because the wind turbines are far from residential areas. MOTIVATION: Install a 2-blade downwind](https://reader035.vdocument.in/reader035/viewer/2022062915/5eb1f37c0241a91a3f521af4/html5/thumbnails/1.jpg)
CFD mesh
Iso-surfaces of vorticity magnitude
Downwind configuration
Iso-surfaces of vorticity magnitude
Upwind configuration
ABSTRACT
Large wind turbines are typically designed to operate in the upwind configuration, wherein the
rotor is located upwind of the tower. However, as blades get larger there is increased possibility
of blade-tower interference, and the use of robust and heavy blades that resist deformation
could be expensive. A downwind rotor may offer a simple, cost-effective solution. A downwind
rotor shows promise, but the optimal use of the concept will require an investigation into the
impact of the tower shadow on the wind turbine loads and power. A Computational Fluid
Dynamics tool solving for full Navier-Stokes equations is used to determine the detailed flow
field developing around two-blade horizontal axis wind turbines (HAWT) in downwind and
upwind configurations. The resulting flow field around the wind turbine is used to evaluate the
noise radiating to the farfield using an acoustic analogy method. The influence of the variation
of wind velocity and rotational speed of the rotor on the sound pressure level is analyzed.
TOOL
The numerical tool used to carry out the simulations of fluid flow around the wind
turbine is an advanced Computational Fluid Dynamics commercial solver ( ANSYS
Fluent). The propagation of sound to the far field is predicted using an acoustic analogy
method (Ffowcs Williams and Hawkings).
COMMENTS AND CONCLUSIONS
Acoustic pressure
Sound pressure level
Sound pressure level
Pressure force in x-direction
Torque
References
[1] Jonkman, J., “NREL Offshore Baseline 5MW,” NREL / NWTC publication, Feb. 2007.
[2] Jonkman, J. M., Butterfield, S., Musial, W., and Scott, G., “Definition of a 5 MW reference wind turbine
for offshore system development,” NREL/TP-500-38060, Golden, CO, Feb. 2009.
[3] ANSYS, Inc., www.ansys.com, Canonsburg, PA.
[4] Hubbard, H.H. and Shepherd, K.P. (1990), Wind Turbine Acoustics, NASA TM DOE/NASA 20320-77.
• The overall effect of the tower wake on the torque seems to be negligible.
• Larger spikes would raise concerns related to structural analysis because they generate
larger deflections of the blades, although, these spikes are not so large.
• The acoustic pressure generated by the downwind configurations is larger compared to
upwind configuration by about 12%.
• The low frequency noise radiating from downwind configurations is higher by about
7db.
• Higher level noise is radiating from systems operating under larger wind velocities.
• However, even if the downwind configurations generate more noise, off-shore designs
are possible because the wind turbines are far from residential areas.
MOTIVATION: Install a 2-blade downwind configuration wind turbine in Lake Erie
Analysis of Tower Shadow Effects and Noise Radiation from Downwind HAWT’s Using a CFD Tool
Adrian Sescu Abdollah A. Afjeh Brett Andersen
Univ. of Toledo, MIME Department Univ. of Toledo, MIME Department Univ. of Toledo, MIME Department
Current affiliation: Johns Hopkins University
Research conducted with support from the US Department of Energy (Grant DE-FOA-0000090) which is gratefully acknowledged.