The authors are thankful to CNPq, FAPEMIG and PUC Minas Airflow CFD Modeling in the Test Section of a Low-Speed Wind Tunnel Matheus S. Guzella*, Daniele Manto**, Cleide B. Soares***, Cristiana B. Maia*, Sérgio M. Hanriot*, Luben Cabezas- Gómez* * Department of Mechanical Engineering, Pontifícia Universidade Católica de Minas Gerais – PUC Minas, Av. Dom José Gaspar, 500, Coração Eucarístico, Belo Horizonte, MG, Brazil, 30535-901 tel/fax: +55 31 3319-4910 e-mail: matheusguzella@gmail.com, cristiana@pucminas.br,hanriot@pucminas.br,luben@pucminas.br ** Stadler Bussnang AG, Ernst-Stadler St. 4 , 9565 Bussnang – Switzerland tel: +41(0)716262020 e-mail: manto.daniele@hispeed.ch *** Department of Mechanical Engineering, Centro Federal de Educação Tecnológica de Minas Gerais, Av. Amazonas, 5253. Nova Suíça. Belo Horizonte, MG, Brazil, 30480-000 e-mail: cleide_bsoares@hotmail.com Submitted: 29/06/2010 Accepted: 26/09/2010 Appeared: 20/11/2010 HyperSciences.Publisher Abstract— This paper presents numerical results and experimental data of the airflow inside a low-speed wind tunnel made of wood, with a square test section with length of 0.79 m and side of 0.2 m. The experimental tests were performed in the exit region of the tunnel test section using a Pitot tube and a hot wire anemometer. The numerical predictions were obtained by solving the Reynolds-Averaged Navier–Stokes (RANS) equations using the Shear Stress Transport k- turbulence model with the ANSYS-CFX® code. A numerical solution of a fully developed turbulent channel flow is also presented for comparison purposes. The numerical values of axial velocity were compared with the measurements in the exit region of the tunnel. The turbulent kinetic energy was compared with experimental data in the central point of the exit cross-section of the tunnel. The results are in good agreement with the experimental data. Keywords: CFD, wind tunnel, SST k- turbulence model, Pitot tube, Hot Wire Anemometry, Analytical Solution 1. INTRODUCTION A wind tunnel is a very powerful tool to help the study of the effects of air moving over or around a body. According to Baker (2007), the first wind tunnels predated the advent of aero planes, with Wenham in 1871, but their development started between 1960 and 1980, becoming a reliable and robust tool for commercial design purposes. Several reports of construction and operational principles of wind tunnels are available in literature, like Diana et al. (1998), Wittner et al. (2000), Balendra et al. (2002) and Cogotti et al. (2008). Experiments performed in wind tunnels are described by several researchers. Bosch et al. (2001) used wind tunnel experiments to establish the effects of wind on cylindrical components in highway support structures of the United States highway system. The authors present the results of force measurements on a representative sample of tapered and non-tapered cylinders. Bartoli et al. (2006) performed wind tunnel tests on an experimental model representing cables under wind loading, evaluating the variation of the axial load at supports at the ends of the cable. Liu et al. (2008) studied mean drag and lift coefficients for groups of two, three, and four cylinders arranged in-line. Drag and lift forces were measured in smooth and turbulent flow conditions. The indoor air pollutant dispersion and possible cross-unit contamination in residential buildings was investigated by Liu et al. (2008), using a boundary layer wind tunnel representing a 10-story residential building. The assessment of ventilation in buildings was studied by some researchers (Bady et. al., 2011, Karava et. al., 2011). Several other studies were performed using wind tunnels: study of the development of secondary instabilities in compressible swept airfoil boundary layers (Li et al., 2010), study on exhaust gas dispersion from road vehicles (Kandaa et al., 2006,a Kandaa et al., 2006,b), study of the characteristics of the flow in wind turbines (Yu et. al., 2011) and the evaluation of the effect of long-term flights in birds (Jenni-Eiermann et al., 2009). Even with the recent computational advances, wind tunnels are an essential tool to the study of aerodynamics. Wind tunnel measurements are used to validate CFD (Computational Fluid Dynamics) calculations. On the other hand, CFD can be used as a tool to support wind tunnel design, wind tunnel testing and the interpretation of the test results. With the development of powerful computers and considering the use of turbulence models, CFD showed great results modeling small particle dispersion (Gorlé et al., 2009), Journal of Advanced Research in Mechanical Engineering (Vol.1-2010/Iss.4) Matheus et al./ Airflow CFD Modeling in the Test Section … / pp. 210-225 210 Copyright © 2010 HyperSciences_Publisher. All rights reserved www.hypersciences.org