Editing Wind tunnel (section)

==How it works==
[[File:Windtunnel1-en.svg|thumb|A wind tunnel diagram which shows a fan drawing air past a model aircraft.<ref>{{cite book |url=https://ntrs.nasa.gov/citations/19810023610 |title=Wind Tunnels of NASA SP-440 |page=2|author1=Hirschel, Ernst Heinrich |author2=Prem, Horst |author3=Madelung, Gero}}</ref> The measurements taken from models are applicable to full-size objects.]]
[[File:Aeroakustik-Windkanal-Messhalle.JPG|thumb|The effect of streamlining is made visible in a wind tunnel. Shaping the body to make it more streamlined reduces fuel consumption.]]
A wind tunnel creates an outdoor environment in a controlled indoor setting which enables measurements of wind forces on a moving object to be taken while the object is stationary. This is much cheaper and more convenient than getting measurements while the object is moving.

The object being tested, such as a scale model of an aircraft, is placed in the test section and restrained from moving. Air is flowed around the object and the forces on the model are measured. The measurements taken from the reduced-scale model are applicable to the full-size aircraft. Testing of scale models of a new aircraft design before it flies is done to ensure the first flight will be safe with the aircraft behaving in a predictable manner. Research in wind tunnels produces accurate results and is done rapidly and economically compared to flight testing of full-scale aircraft.

Few people see a wind tunnel or are aware of their existence but work done in their test sections affects every-day life. For example, streamlining investigates ways to reduce the air drag on airliners, cars, and racing cyclists. The requirement for streamlining is not always the same, for airliners and cars it is to reduce fuel consumption, for racing cyclists it is to increase speed.

Car fuel consumption is of secondary importance to drivers when starting and driving in extreme cold and wind-driven snow. This condition is investigated in a different kind of wind tunnel, the climatic wind tunnel. The test section subjects cars to a range of extreme environmental conditions to make sure the air conditioning can make the car comfortable on very hot and very cold days and can keep windows clear of condensation in very humid and cool weather.