An Experimental Investigation of NACA Submerged-Duct Entrances

Charles W. Frick, Wallace F. Davis, Lauros M. Randall, Emmet A. Mossman
naca-acr-5i20
November, 1945


The results of a preliminary investigation of submerged-duct entrances are presented. It is shown that an entrance of this type posses desirable critical speed and pressure recovery characteristics when used on a fuselage or nacelle in a region of low incremental velocity and thin boundary layer. The data obtained indicate that submerged entrances are most suitable for use with internal-flow system which diffuse the air only a small amount: for example, those used with jet motors which have axial-flow compressors. When complete diffusion of the air is required, fuselage-nose or wing leading-edge inlets may prove to be superior. The results of the investigation have been prepared in such a form as to permit their use by a designer and the application of these data to a specified design is discussed.

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