Distribution of Heat-Transfer Coefficients Around Circular Cylinders in Crossflow at Reynolds Numbers From 20 to 500

Abstract An experimental investigation using the Zehnder Mach interferometer reveals the temperature field around heated cylinders in an air stream normal to the axis. From the temperature distribution the local distribution of the heat-transfer coefficient around the cylinder circumference is obtained. The thermal boundary layers are quite thick, especially for the lower Reynolds numbers investigated and the separation occurs farther downstream than at high Reynolds numbers. Accordingly, the contribution of the stagnant region at the downstream side of the cylinder to the over-all heat transfer is low (approximately 15 per cent), and the heat flow into the upstream side is much larger than into the downstream side.