Archival correlations for average heat transfer coefficients for non-circular and circular cylinders and for spheres in cross-flow

Abstract

Average Nusselt number information was collected for all textbook-standard, non-circular cylinders in cross-flow in air. These non-circular cross-sections include: squares, diamonds, flat plates perpendicular to the freestream, ellipses, hexagons, rectangles, and circles. This collection encompassed both venerable data which form the basis of the correlations recommended by current textbooks and all of the modern data that could be found in the literature. For each of the selected non-circular cross-sections, the available data were displayed, evaluated, and compared with those for all related cross-sections. On the basis of the merits of the information collected for each cross-sectional shape, correlations are recommended which are intended to form a new set of textbook standards. Also, the new correlations avoid errors made in the current textbook correlations which are caused by an inconsistency in the selection of the characteristic dimension relative to that used by the original investigators. Almost exclusively, the new correlations are based on modern experimental data. In order to provide a complete compendium of cross-flow heat transfer information, correlations for the circular cylinder and the sphere have been included in the table. The correlation for the circular cylinder is original to this paper.