Gradient heatmetry and PIV combination in the study of flow in an oval-trench dimple

Abstract

An experimental convective heat transfer study is carried out to explore if the local heat transfer coefficient into an oval-trench dimple can outnumber to the well-known heat transfer on the smooth surface. Bismuth-based gradient heat flux sensors were used on a single oval-trench dimple mounted the surface. The experiments were performed in a wind tunnel in the Reynolds number range from 5·103 to 3·104. The option is considered when the angle of inclination the dimple’ longitudinal axis to the free-stream velocity vector is 45°, and the relative depth is 0.25. Under experimental conditions, a constant temperature Tw is maintained on the heat transfer surface. The distributions of the local heat transfer coefficient are obtained. For characteristic transverse cross-section, the double increase in heat transfer in compared to the smooth surface. The heat transfer enhancement’ mechanism associated with the separated flow and vortex formation in the dimple is discussed.