A wind tunnel is a tool used in aerodynamic research, that helps study the effects of air moving past a solid object. A wind tunnel usually consists of a air producing device; such as a fan, a cylidrical passage and a test object in the middle. Wind tunnel testing can be applied using full scale or scaled versions of the test object.
The first wind tunnels were designed to study vehicles like planes in free flight. Wind tunnels allowed the object to stand still and have air move past, which saves energy and space. Also this allowed a stationary observer to study the aerodynamics of the test object.