Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Effects of canopy architecture in wind-energy potential for power generation by wind turbines
Submission Author:
Mario Benjamim Baptista de Siqueira , DF , Brazil
Co-Authors:
Mario Benjamim Baptista de Siqueira, Antonio Brasil Junior, Luis Aramis Dos Reis Pinheiro
Presenter: Mario Benjamim Baptista de Siqueira
doi://10.26678/ABCM.COBEM2023.COB2023-2204
Abstract
Wind turbines are invariably inserted in a region of the atmosphere called the Atmospheric Boundary Layer (ABL), which is directly influenced by the presence of the Earth's surface and responds to surface forcings. As such, the ABL comprises the part of the troposphere closest to the surface with a vertical dimension of the order of 1km during the day. However, the lowermost layers of the CLA are directly affected by the geometry of the elements that constitute the surface roughness, the so-called roughness sub-layer, which can extend up to 4 heights of these elements. Therefore, as wind turbines have rotor heights close to 100m, besides being always in the CLA, depending on the surface cover where it is inserted, it might be under the effects of the vegetation architecture, i.e., canopy height and leaf area distribution, LAD. In this work, it was examined the effects of different vegetation covers on the potential for electrical power generation by wind turbines. Two types of vegetation were considered that are quite distinct in both their geometric and phenological characteristics, namely, native Cerrado and a Eucalyptus plantation. A one-dimensional (vertical) atmospheric flow model based on the solution of the Reynolds-averaged Navier-Stokes equations with second order closure, was developed for canopy flow, where its elements such as foliage, branches and trunks act as sinks for linear momentum. Dry and wet season simulations, characteristic of the Brazilian Centro-Oeste, with corresponding LAD for each vegetation in these seasons, were performed. Boundary conditions for the simulations were taken from the experiment conducted at Fazenda Água Limpa, University of Brasilia, in the two vegetation covers. Mean velocity values at 100m height were calculated for the two covers and periods considered. Note that in the Cerrado the values for dry and wet seasons, 6,92 m/s and 6,84 m/s, respectively, are very close with a slightly higher average for the dry period, approximately 1%. For Eucalyptus, on the other hand, a more pronounced difference, 4.38 m/s and 5.49 m/s, close to 20%, were found. Comparing now the effects of vegetation cover, it was verified that during the humid period, the speed at 100m is almost 20% higher in the Cerrado. In the dry period, this difference reaches more than 35%.
Keywords
wind energy, Canopy flow, atmospheric boundary layer
