E.R. van Driest

General expressions for recovery factor and Reynolds analogy factor involving variable Prandtl number are derived for thin laminar and turbulent boundary layers with zero pressure and temperature gradients along the plate using the Crocco transformation. When the flow is laminar, the Prandtl number variation is obtained from the NBS-NACA Tables of Thermal Properties of Gases. Theoretical recovery factors and Reynolds analogy factors are then computed for the flow of air on flat plates in atmospheric free flight and in heated wind tunnels. The theory is compared with experimental data on recovery factor. With turbulent flow, the von Karman analogy between heat transfer and fluid friction is extended to take into account the turbulence Prandtl number and the shear distribution across the boundary layer. A corresponding expression for recovery factor is also derived. Experimental data on turbulence recovery factor is then used to obtain the turbulence Prandtl number which in turn is substituted into the formula for Reynolds analogy factor to yield a more accurate relation between heat transfer and skin friction. Heat-transfer coefficients obtained by applying the Reynolds-analogy factor to skin-friction theory are compared with heat-transfer data for air at supersonic speed.

WGL-Tagung, Duisburg, 1954

Conference Paper

englisch

21,0 x 29,7 cm, 10 Seiten

Jahrbuch der Wissenschaftlichen Gesellschaft für Luftfahrt, 1954, Band I, ; S.66-75; 1954; Braunschweig : Vieweg

NA

Bestellbar

1955