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Investigations of Effects of Surface Temperature and Single Roughness Elements on Boundary-Layer Transition

Liepmann, Hans W. and Fila, Gertrude H. (1947) Investigations of Effects of Surface Temperature and Single Roughness Elements on Boundary-Layer Transition. National Advisory Committee for Aeronautics , Washington, D. C.. http://resolver.caltech.edu/CaltechAUTHORS:LIEnacarpt890

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Abstract

The laminar boundary layer and the position of the transition point are investigated on a heated flat plate. It was found that the Reynolds number of transition decreases as the temperature of the plate is increased. It is shown from simple qualitative analytical considerations that the effect of variable viscosity in the boundary layer due to the temperature diference produces a velocity profile with an inflection point if the wall temperature is higher than the free-stream temperature. This profile is confirmed by measurements. Furthermore, it is confirmed that, even with large deviation from the Blasius condition, the velocity and temperature profiles are very nearly identical, as predictable theoretically for a Prandtl number [sigma] of the order of 1.0 (for air, [sigma]=0.76). The instability of injection-point profiles is discussed. Studies of the flow in the wake of large, two-dimensional roughness elements are presented. It is shown that a boundary laysr can separate and reattach itself to the wall without having transition take place.


Item Type:Report or Paper (Technical Report)
Record Number:CaltechAUTHORS:LIEnacarpt890
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:LIEnacarpt890
Alternative URL:http://naca.larc.nasa.gov/reports/1947/naca-report-890/naca-report-890.pdf
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:448
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:20 Jun 2005
Last Modified:26 Dec 2012 08:40

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