Experimental investigations of the compressible turbulent boundary layer at very high reynolds numbers

The present experimental program was undertaken with the objective of extending the Reynolds number range of available experimental skin-friction data to approximately 109. Included in this paper are the results of two series of tests in which local surface shear stress and boundary-layer velocity profile measurements were made on aerodynamical ly smooth isobaric, adiabatic surfaces. The tests were conducted in the LTV High-Speed Wind Tunnel at a nominal Mach number of 2.8. In the first series, a 10-ft-long flat-plate model served as the test surface. In the second series, the floor of the tunnel supersonic diffuser, modified to provide an effective extension of the tunnel test section, was the test surface. The paper contains a description of the test apparatus and procedures as well as a discussion of the results. The program objective was accomplished in that a Reynolds number range of 2.32 X 10 7 ^ Rx = 1.41 X 10 9 was covered. These results represent a significant extension of the Reynolds number range of available experimental skin-friction data. Nomenclature Cf = local skin-friction coefficient M = Mach number P = pressure Pt2 = total pressure behind a normal shock q = dynamic pressure Rx = Reynolds number based on x — Re = Reynolds number based on 6 R = gas constant T ~ absolute temperature U = velocity UT = friction velocity — (rw/pw}1/z x = distance along test surface in direction of flow y = coordinate distance normal to the test surface 7 = specific heat ratio 6 = boundary-layer thickness d* = displacement thickness T] = law of the wall dimensionless spatial coordinate — pwU7y/ Vw 9 = boundary-layer momentum thickness [Eq. (11)] (j, = viscosity p — mass density <r = compressibility factor - { [(7 - l)/2]Mi 2}{! + [(T