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

摘要

Flow around cylinders is a widely studied field where the turbulence generating properties are used primarily for heat transfer enhancement. By augmenting the cylinder surface, it is possible to develop additional secondary flows which may increase thermal and hydraulic performance of cylinders. This experimental study looks at the effect that dimples have on the flow behind a pinfin within a staggered array. The test section consisted of a staggered array of 13 rows of 50 mm pin-fins with 5 pins-fins in each row. The pinfins had a streamwise spacing X=D and a spanwise spacing S=D of 2. The height ratio H=D was 1.28. A smooth and a dimpled pin-fin configuration was tested. Measurements were taken using a L-shaped five-hole probe between the 10th and 11th row of the array at mid-height for Reynolds numbers of 15 000 and 40 000. The three velocity components and vorticity are analyzed. The results primarily show a decrease in the size and effect of the wake as well as the presence of additional vertical flows.