Preliminary wind-tunnel investigation of the effect of area suction on the laminar boundary layer over an NACA 64A010 airfoil Page: 2 of 16
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NACA RM No. L7L15
NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
PRELIMINARY WlNlD- QNNEL INVESTIGATION OF THE EFFECT
OF AREA SUCTION ON THE LAMINAR BOUNDARY LAYER
OVER AN NACA 64AO10 AIRFOIL
By Albert L. Braslow, Fioravante Visconti, and Dale L. Burrows
A preliminary investigation was made in the Langley two-dimensional
low-turbulence tunnel on an NACA 64A010 airfoil with permeable surfaces
to obtain an indication of the stabilizing effect of area suction on the
laminar boundary layer. Boundary--layer velocity profiles were measured
at Reynolds numbers of 2.0 x 10, .0 x 106, and 6.0 x 106 and at various
chordwise stations for values of the flow coefficient up to 0.012.
Although the surfaces of the airfoil model that was tested had many
waves and irregularities of contour, the data corroborated qualitatively
the theoretically predicted stabilizing effect of area suction on a smooth
flat plate. The suction quantity required for the wavy airfoil tested,
however, was much greater than the theoretical value for a smooth flat
The stability theory for the incompressible laminar boundary layer
is based on theoretical analyses of the damping or amplification of
mathematically small two-dimensional aerodynamically possible disturbances
in the boundary layer (reference 1). A possible definition in the
physical sense of a small disturbance is that a small disturbance does
not produce transition from laminar to turbulent flow at its origin in
contrast with a large disturbance, which does cause immediate transition.
Small disturbances may either amplify, as they progress downstream and
eventually grow large enough to cause turbulence, or they may be damped
and cause no change in the downstream flow; if small disturbances of all
frequencies tend to be damped rather than amplified, the laminar boundary
layer is considered stable (reference 2).
Theoretical investigations have been made of the characteristics of
flows past a flat plate through which there is a small normal velocity,
and, in addition, the stability theory has been used to calculate the
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Braslow, Albert L.; Visconti, Fioravante & Burrows, Dale L. Preliminary wind-tunnel investigation of the effect of area suction on the laminar boundary layer over an NACA 64A010 airfoil, report, April 26, 1948; (digital.library.unt.edu/ark:/67531/metadc58230/m1/2/: accessed November 14, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.