Effects of Turbulence on Laminar Skin Friction and Heat Transfer

Experiments were performed in two low-turbulence wind tunnels (u∞′ < 0.1%) to determine the effects of turbulence on heat transfer from plates and circular cylinders in incompressible flow. Grid turbulence up to 6% was imposed. Heat transfer was increased about 30% in the laminar region of a flat plate and up to 70% on a circular cylinder; smaller though still significant increases in shearing stress at the wall were measured by hot wires near the surface. A phenomenological theory is given which shows good agreement with the experiment.