Wind tunnel

A facility that drives controlled airflow past models or objects so their aerodynamic forces, flow patterns, or other effects can be measured.

Boundary layer: A thin region near a surface where fluid velocity changes from zero at the wall to the surrounding flow speed. Its growth along tunnel walls can distort the airflow reaching a test model.
Aerodynamics: The study of air and other gases in motion and their interaction with bodies. Wind tunnels are experimental facilities for investigating this broader subject.
Aircraft design: The engineering process of defining an aircraft's configuration and ensuring it meets performance and safety requirements. Model tests compare configurations and estimate aerodynamic loads before flight.
Open-circuit wind tunnel: A wind tunnel that draws air from the surroundings and exhausts it back into the surroundings. It contrasts with recirculating designs by using a single-pass airflow path.
Francis Herbert Wenham: A British engineer and aviation pioneer who built an early wind tunnel in 1871. His apparatus helped establish systematic airflow testing of aerodynamic surfaces.
Reynolds number: A dimensionless ratio of inertial forces to viscous forces in fluid flow. Matching it helps reproduce full-scale flow behavior with smaller models.
Lift (force): The component of fluid force perpendicular to the direction of relative flow. Tunnel tests measure how a model's shape and attitude generate lift.
Automotive aerodynamics: The study and design of airflow around road vehicles to manage drag, lift, stability, and cooling. Automotive tunnels measure forces and airflow around vehicle shapes.
Closed-circuit wind tunnel: A wind tunnel that recirculates air through a continuous loop. Its return circuit can improve efficiency and stabilize test conditions.
Octave Chanute: A French-born American civil engineer and aviation pioneer who investigated glider design and flight. His late-nineteenth-century experiments helped spread wind-tunnel methods among aviation researchers.

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