Local coefficients of skin friction and heat transfer for turbulent boundary layers on two-dimensional diffusers

Abstract

This report considers the changes of local coefficients of skin friction and heat transfer for turbulent boundary layers in two-dimensional subsonic air streams under rising pressure gradients. The values of the local coefficients of skin friction and heat transfer are compared on the basis of Reynolds' Analogy, von Karman's improvement to Reynolds' Analogy, and on the basis of similar velocity and temperature boundary-layer profiles. Tests on diffusers at total angles of 4 deg and 7 deg showed that the local coefficients of heat transfer based on the measured heat transfer values, increased with increase of the strealn velocity and diffuser angle relative to the local coefficients of heat transfer, based on Reynolds' analogy and on von Karman's improvement to Reynolds' analogy. The local coefficients of heat transfer calculated on an assumed similarity of velocity and temperature distributions were unsatisfactory.