A wind tunnel is a tool used in aerodynamic research to study the effects of air moving past solid objects. A wind tunnel consists of a closed tubular passage with the object under test mounted in the middle. A powerful fan system moves air past the object; the fan must have straightening vanes to smooth the airflow. The test object is instrumented with a sensitive balance to measure the forces generated by airflow; or, the airflow may have smoke or other substances injected to make the flow lines around the object visible. Full-scale aircraft or vehicles are sometimes tested in large wind tunnels, but these facilities are expensive to operate and some of their functions have been taken over by computer modelling. In addition to vehicles, wind tunnels are used to study the airflow around large structures such as bridges or office buildings. The earliest enclosed wind tunnels were invented in 1871; large wind tunnels were built during the Second World War.
Read more about Wind Tunnel: Theory of Operation, Measurement of Aerodynamic Forces, How It Works, Flow Visualization, Classification, List of Wind Tunnels
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