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National Advisory Committee for Aeronautics, Technical Notes - Boundary Layer Development and Skin Friction at Mach Number 3.05

Boundary-layer studies consisting of schlieren observations and
momentum surveys were made on hollow cylinder models with their axes
alined parallel to the stream. Results were obtained for three model
diameters and for natural and artificially induced turbulent boundary-
layer flows.

Transition Reynolds numbers were found to decrease with decreases
in leading-edge thickness and with reductions in tunnel pressure level.
Turbulent temperature-recovery factors generally decreased with increasing
Reynolds number and were a maximum for the smallest transition Reynolds
numbers.

The results of this investigation appeared to be consistent with
the theoretical turbulent friction formulas of Wilson and with the extended
Frankl-Voishel analysis of Rubesin, maydew, and varga. Velocity profiles
in the outer portion of the boundary layer could be approximated reason-
ably with a 1/7 power profile and were found to be approximately similar
in this region. Velocity profiles.given by the Kfirman.universal turbulent
boundary—layer profile parameters were found to be similar in the laminar
sublayer and in the turbulent region.

Total-pressure surveys of the turbulent boundary layer at supersonic
speeds are made and analyzed in references 1, 2, and 3 for the purpose
of determining skin-friction coefficients as a function of Reynolds
number.

Results of an investigation of a flat plate model spanning the
tunnel are reported in reference 1. Turbulent boundary layers were
formed by the natural transition from laminar to turbulent flow and '
surveys were made at several positions along the model length. The Mach
number of the stream was varied from 1.70 to'2.19 and the tunnel was
operated at a ponstant stagnation pressure at each Mach number, giving
a maximum Reynolds number of about 22x106 for the turbulent boundary
layer. To obtain the results given in reference 5, a smaller flat plate
model was used and turbulent boundary layers were formed by the rapid
artificial transition to turbulent flow.

Integrated friction coefficients were obtained in reference l by
equating the measured momentum defects to the drag and making suitable
corrections to the length of turbulent run because of the presence of the
laminar boundary layer upstream. In reference 5 corrections to the length
of run were necessary because of the high initial thickness of the
boundary layer near the leading edge caused by the coating used to promote
early transition to turbulent flow.