Experimental Studies and Correlations of Convective Heat Transfer in a Radially Rotating Serpentine Passage

The present paper investigates experimentally the effects of rotation on the convective heat transfer of air flow in a radially rotating three-passage serpentine square channel. Due to rotation, the cross-stream and radial secondary flows are induced by the Coriolis force and the centrifugal-buoyancy force, respectively. The channel walls were made of low thermal conductivity material for suppressing wall heat conduction. The wall surfaces were heated individually by four separate stainless-steel film heaters to distinguish the local heat transfer rates. The hydraulic diameter and the mean rotational radius of the flow passages were 4 and 180 mm, respectively. The governing parameters are the through-flow Reynolds number Re, the rotation number Ro, the buoyancy parameter Gr* and the main flow direction. The results show that the local heat transfer rate was enhanced by rotation on the trailing side for outward flow and on the leading side for inward flow. In the first and third passages, the effect of rotation on heat transfer is relatively prominent. The buoyancy effect is favorable to the heat transfer enhancement on four sides of these passages. The data of Nu_Ω/Nu₀ are correlated on the leading and trailing sides of these passages.