Characteristics and calibration of the mexican boundary layer wind tunnel at UNAM

Abstract

With the aim to improve and promote Mexican Wind Engineering research, a low-speed closed return wind tunnel for atmospheric environment and structural wind-loading simulations was built at the National Autonomous University of Mexico (UNAM). The testing calibration procedure was developed based on many recommendations specified by several authors on the literature to assure compliance with full-scale measurements, laboratory results and international coding. The calibration procedure consists of four stages: the first stage is to represent adequately the atmospheric boundary layer; the second, to obtain adequate pressure coefficients for rigid models; the third, to perform tests to obtain the aerodynamic forces and some dynamic properties from structural models; and the fourth is to develop aeroelastic models. This paper focuses on the first two stages. Therefore, during the first stage, various tasks were developed to perform adequate representation on the lower-portion of the atmospheric boundary layer to characterize mean velocity profiles and turbulence fluctuations. On the second stage, the main task was to replicate external mean pressure coefficients of a typical cubic low-rise building as many other laboratories have done before. During the first stage it was possible to adequately replicate an urban atmospheric boundary layer artificially. During the second stage, some results reveal the need to update the current Mexican regulations for wind design, since some pressure coefficients considerably exceeds the threshold values. Finally, although other types of tests are in progress, it is considered that the new boundary layer wind tunnel of the UNAM can be used with confidence to test different type of structures and contribute to the development of Mexican Wind Engineering.