Developing Heat Transfer in Rectangular Ducts With Staggered Arrays of Short Pin Fins

Streamwise heat transfer variation, overall array heat transfer, and overall flow friction behavior are presented for large aspect ratio ducts containing uniformly spaced staggered arrays of circular pin fins which span the entire duct height. The array geometries investigated have short pin heights (length-to-diameter ratio of 1) and moderate spanwise (transverse) and streamwise (longitudinal) pin spacings (pitch-to-diameter ratios of 1.5 and 2.5). Such staggered array geometries are typical of applications found in internally cooled gas turbine engine airfoils. The uncovered duct walls comprise a substantial fraction of the total heat transfer area. Ten pin rows in the streamwise direction are utilized in all the experiments, with a segmented construction allowing determination of spanwise-averaged heat transfer coefficients resolved to a single row spacing in the streamwise direction. Comparisons are made with results of prior studies which are mainly restricted to flow normal to banks of circular cylinders with long length-to-diameter ratios.