Regularities of flow and heat transfer at the surface of transversely finned tubes

A great number of experimental investigations allowing one to reveal the physical mechanism of processes responsible for their thermal and hydraulic performance are carried out in attempt to solve problems of updating constructions and methods of thermal design of heating surfaces of transversely finned tubes widespread in power engineering. Results of flow visualization and investigation of pressure fields and local heat transfer at the fin surface over the Reynolds number range Re = (1.0 ⋯ 6.6) · 104 are presented for the case of a wide variation of geometric characteristics of finned tubes and parameters of their arrangement in a bundle. Regularities substantially changing the existing concept of transfer processes in the interfin space and in the wake behind a finned tube are revealed. It is found that the flow behavior and the distribution of local heat transfer coefficients over the fin surface change significantly at the fin height-to-finned tube diameter h/d approximately equal to 0.4. The results obtained are generalized in the form of the patterns of flow and heat transfer at the finned tube surface, including seven characteristic regions and four types of flow separation.