The effect of hemispherical dimple spacing on flow structure and heat transfer characteristics of internal flow using CFD

Abstract

A simulation study of flow and heat transfer on a dimpled surface is presented. A 3-D model was tested in a wind tunnel with rectangular cross section. A row of dimples with inline arrangement were formed on the internal wind tunnel surface, so that the centerline of dimples was perpendicular to the air flow. The dimples were made with 40 mm diameter sphere, and the printed diameter of dimples on the surface was D=26.4 mm. The depth of a dimple was H=0.2D. The dimple-to-dimple spacings tested were S=1.125D, 1.25D, 1.5D and 2D. The Reynolds number of internal flow, based on the hydraulic diameter of the wind tunnel, was 20,000. The fluid flow and heat transfer were numerically solved using a Shear Stress Transport (SST) k-ω turbulence model. The results show that at S=1.125D, peak Nusselt numbers downstream of the dimples were found in two regions, whereas for cases with S≥1.25D there was a single such region.

Keywords

• cfd
• dimple
• heat transfer
• turbine blade cooling