DOI: 10.1615/THMT-18
ISBN Print: 978-1-56700-468-7
ISBN Online: 978-1-56700-467-0
ISSN Print: 2377-2816
Flow field measurements of a round jet impinging on smooth and dimpled surfaces
RÉSUMÉ
While heat transfer in channel flows is enhanced by dimpled surfaces, little is known about jets impinging on them. Here, the interaction of primary and secondary vortices generated by an impinging round jet (diameter D) on smooth and dimpled surfaces is investigated using planar particle image velocimetry. Both square and round dimple openings (1/4D) with different internal shapes were investigated. Measurements were performed at Re = 1,500, 6,400 and 12,400 at a stand-off distance of 5D. Primary and secondary vortices were detected based on directional swirling strength maps. Analysis of their numbers, strength and area revealed no significant effect of the dimples for Re = 6,400 and 12,400 while for Re = 1500, vortex strengths were initially slightly smaller for the smooth plate. Our results indicate that the outer layer of the wall jet is hardly affected by the dimples.