The first wind tunnel was constructed in 1871 by Frances Wenham in England. Since then, wind tunnels have been built in a large variety of sizes and shapes, depending on there specific applications. A wind tunnel includes a test section, where the model is mounted. If a supersonic air-stream is required, large tanks of compressed gas usually are employed, producing the high velocity stream by allowing the gas to expand through a suitably shaped nozzle into the test section. Instrumentation is provided in the test section to permit measurement of forces and pressures acting on the model and to measure other quantities of interest.
Techniques are available to allow visualization of the air flow as well.
Wind tunnels in use today have test sections with cross section dimensions as large as 12 to 24 m or 40 to 80 ft. Velocities up to 20 times the speed of sound are produced in in supersonic wind tunnels.