Heat Transfer Around a Circular Cylinder Near a Plane Surface

An experimental study has been conducted on the effect of the clearance (c) between a circular cylinder and a plane surface on the heat transfer from the cylinder to a cross flow of air. The test cylinder diameters (d) were 10.1, 15.2, and 25.2 mm. The turbulent boundary layer thickness (δ) along the wall with no cylinder present was varied from 15 to 19 mm. The Reynolds number (Re) based on the undisturbed uniform flow velocity above the wall ranged from 10⁴ to 6.6×10⁴. Variations of the characteristic features of the local and mean Nusselt numbers are discussed in relation to the values c/d, δ/d, and Re investigated.