NACA duct

The NACA duct or NACA scoop is a common form of low-drag intake design, orginally developed by the National Advisory Committee for Aeronautics in 1945. When properly implemented, it allows fluid to be drawn into an internal duct, often for cooling purposes, with a minimal disturbance to the flow. The design was originally called a "submerged inlet," since it consists of a shallow ramp with curved walls recessed into the exposed surface of a streamlined body, such as an airplane or race car.

Related Topics:
Drag - Intake - National Advisory Committee for Aeronautics - 1945 - Airplane - Race car

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The design is believed to work because the combination of the gentle ramp angle and the curvature profile of the walls creates counter-rotating vortices which suck in the boundary layer while avoiding the form drag and flow separation that can occur with protruding inlet designs. However, this type of flush inlet generally cannot achieve the larger ram pressures and flow volumes of an external design, and so is rarely used for the jet engine intake application for which it was originally designed.

Related Topics:
Boundary layer - Jet engine

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