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Boundary-layer analysis of subsonic inlet diffuser geometries for engines nacellesTheoretical Mach number distributions and boundary-layer parameters are presented for subsonic nacelle inlet diffuser geometries with length to exit diameter ratios ranging from 0.4 to 1.6 and diffuser exit area to throat area ratios ranging from 1.1 to 2.0. The major portion of the study was done with a cubic diffuser contour with the inflection point at the midpoint of the diffuser, a diffuser throat Mach number of 0.6, and a free-stream Mach number of 0.12. Calculations were performed at both model (diffuser exit diameter, 30.5 cm) and full-scale (diffuser exit diameter, 183 cm) sizes. Separation limits were defined by establishing a separation boundary on plots of diffuser area ratio as a function of diffuser length to diameter ratio. The effects of diffuser contour, inlet lip geometry, and throat Mach number on the boundary-layer characteristics are illustrated. The major results of the study indicate that the separation boundary is shifted to greater area ratios by (1) increasing the diffuser length, (2) increasing the scale of the diffuser and, (3) moving the inflection point of the diffuser contour to or ahead of the midpoint of the diffuser.
Document ID
19740010812
Acquisition Source
Legacy CDMS
Document Type
Other - NASA Technical Note (TN)
Authors
Albers, J. A. (NASA Lewis Research Center Cleveland, OH, United States)
Felderman, E. J. (NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
September 3, 2013
Publication Date
March 1, 1974
Subject Category
Fluid Mechanics
Report/Patent Number
NASA-TN-D-7520
E-7816
Accession Number
74N18925
Funding Number(s)
PROJECT: RTOP 501-24
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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