FLOW FIELD AROUND DIMPLED SHORT PIN-FINS IN A STAGGERED ARRAY

摘要

Flow around cylinders is a widely studied fieldwhere the turbulence generating properties areused primarily for heat transfer enhancement. Byaugmenting the cylinder surface, it is possible todevelop additional secondary flows which mayincrease thermal and hydraulic performance ofcylinders. This experimental study looks at theeffect that dimples have on the flow behind a pinfinwithin a staggered array. The test section consistedof a staggered array of 13 rows of 50 mmpin-fins with 5 pins-fins in each row. The pinfinshad a streamwise spacing X=D and a spanwisespacing S=D of 2. The height ratio H=D was1.28. A smooth and a dimpled pin-fin configurationwas tested. Measurements were taken usinga L-shaped five-hole probe between the 10th and11th row of the array at mid-height for Reynoldsnumbers of 15 000 and 40 000. The three velocitycomponents and vorticity are analyzed. Theresults primarily show a decrease in the size andeffect of the wake as well as the presence of additionalvertical flows.