Experimental and Numerical Study of Heat Transfer and Turbulent Flow in a Rotating channel with V Rib-Dimple Hybrid Structures

Abstract

Heat transfer and turbulent flow structure of novel hybrid structures with V rib-dimple arrays in channels with a sudden contraction have been investigated through experimental and numerical studies for the Reynolds number (Re) from 10,000 to 200,000 and Rotation number (Ro) from 0 to 0.413, which are also compared with those of a smooth and a dimpled only channel. For rotating smooth channels, sudden contraction can significantly enhance heat transfer in the entrance region for the first 4 times Dh of the channel, and heat transfer rates for trailing and leading walls are higher compared with those of static channels. For the rotating V rib-dimple channel at Re = 10,000, heat transfer rates of the trailing wall significantly increase by about 39.13% at Ro = 0.413 compared with those under the non-rotating state, which is because the longitudinal vortex on the trailing side becomes stronger with the actions of the Coriolis force produced by the rotation, thus significantly enhancing heat transfer there. It is also noted that strong longitudinal vortex pairs from inside the dimples of the V rib-dimple structure can partially offset influences of the rotation effects. Therefore, the maximum heat transfer difference between leading and trailing sides of rotating V rib-dimple channels is just 22.57%, which is much smaller than the difference of 107.25% of the rotating dimpled only channel.