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Wind tunnel of atmospheric boundary layer: calibration and building openings simulations using reduced models

Abstract

The natural ventilation of the buildings, used to provide thermal and hygienic comfort of its users, is a strategy to reduce the consumption of energy, because it uses openings and/or passive devices to produce the air movement inside the places. It is important to know and quantify some variables like speed, pressure, temperature, and pressure coefficient to study the effects of the wind in a building, because the behavior of the air inside a building depends on these variables.The setting -up of a wind tunnel of atmospheric boundary layer is being finished in the Laboratory of Environmental Comfort of Civil Engineering and Architecture College of UNICAMP, where this project will be developed. This equipment will provide the ventilation test, related to thermal comfort, which will be made using reduced models of buildings.Therefore, the aims of this project are: acquire the equipments necessary to measure the velocity and the pressure in simulations using reduced models of buildings in the wind tunnel, calibrate the wind tunnel, that is, install equipment to measure the speed and pressure in the test section of the tunnel; construct and install a probe to measure the speed and/or the pressure of the test section; determine the intensity of turbulence in the test section before and after installing obstacles that generate turbulence, measuring the variation of speed; evaluate the uniformity of the average draining in the test section before and after installing the obstacles, measuring the speed and/or the pressure in several places inside the transversal area of the test section; construct and install obstacles that generate turbulence in the test section to simulate the atmospheric boundary layer; and, after the calibration tests, construct reduced models of buildings with openings in different parts and with different levels of internal obstruction; test the reduced models using different speeds and angles of incidence of the wind in the building and measure the speed and the pressure, internal and external; compare the achieved data in the tests with the results of the principal simplified methodology of evaluating the natural ventilation existing in literature; provide a new simplified methodology of evaluating the natural ventilation.Based on the results of this project, it is expected to help, mainly, the small and medium offices that work on projects in terms of thermal comfort, however, in many cases, they can't afford having specialized professionals to use sophisticated and expensive software to evaluate the natural ventilation. (AU)