Artist's concept picture of a submerged inlet for a jet airplane
The NACA duct or NACA scoop is a common form of low-dragintake 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. For a solid object moving through a fluid or gas, drag is the sum of all the aerodynamic or hydrodynamic forces in the direction of the external fluid flow. ... An intake is an air intake for an engine. ... NACA official seal The National Advisory Committee for Aeronautics (NACA) was a U.S. federal agency founded on March 3, 1915 to undertake, promote, and institutionalize aeronautical research. ... 1945 was a common year starting on Monday (link will take you to calendar). ... Fixed-wing aircraft is a term used to refer to what are more commonly known as aeroplanes in Commonwealth English (excluding Canada) or airplanes in North American English. ... Auto racing (also known as automobile racing or autosport) is a sport involving racing automobiles. ...
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 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. In physics and fluid mechanics, the boundary layer is that layer of fluid in the immediate vicinity of a bounding surface. ... A Pratt and Whitney turbofan engine for the F-15 Eagle is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escape. ...
References
Frick, Charles W.; Davis, Wallace F.; Randall, Lauros M.; and Mossman, Emmet A.: An Experimental Investigation of NACA Submerged Duct Entrances. NACA ACR 5120, 1945.
I decided to try a NACAduct, which is designed to be low drag, and to place it just in front of the canopy, where a high pressure zone is likely to build.
The entrance lip at the rear of the duct should be a blunt airfoil leading edge shape; however, the edge formed by the duct and the surface elsewhere should remain crisp.
I drew the outline of the duct on the fairing just forward of the canopy, as that would enable me to use a very short duct to redirect the air toward my face, and I figured there would be a high pressure zone in that area.
Feeds |
Contact