Environmental wind tunnels

Abstract

A considerable variety of wind tunnels have been designed and constructed to investigate a wide range of aerodynamic tasks. Nowadays, environmental wind tunnels designed to simulate Atmospheric Boundary Layer are very attractive. They are used to determine air pollution, wind loads on buildings and constructions, snowdrift, accident with the discharge of harmful substances, pedestrian wind comfort, etc. Several requirements for experiments in meteorological or environmental tasks have to be fulfilled in order to transfer results from small scale wind tunnel experiments to full scale: 1) proper scaling: matching the scale of the model and the boundary layer scale; 2) matching dimensionless similarity numbers, especially the Reynolds numbers; 3) proper simulation of air flow, including distribution of velocity and turbulence characteristi7cs within the boundary layer; 4) acquiring the zero pressure gradient for equilibrium boundary layer. The similarity requirements are the starting point for the environmental wind tunnel design. Some types of these wind tunnels are introduced in this chapter, and their construction is briefly described. Integral part of environmental wind tunnel laboratories is their experimental equipment.Special devices are described, including systems for flow visualization, for turbulent characteristics and concentrations measurements. Some examples of the tasks solved in the environmental wind tunnels are mentioned at the end.& copy 2013 Nova Science Publishers, Inc.