Numerical investigation of turbulent flow and heat transfer in internally finned tubes

A numerical investigation of periodically fully developed, steady, single-p hase, turbulent flow and heat transfer in two spirally finned tubes has bee n first performed. A two-layer turbulence model was applied to model the ne ar-wall turbulence. An unstructured finite-volume method was employed to re solve the complex geometry of internally finned tubes. The effects of grid independence and skewness were extensively examined. In the range of 6,000 less than or equal to Re less than or equal to 70,000 and Pr = 4, the lengt h-averaged friction factors and Nusselt numbers were compared with the expe rimental data of Vlakancic (1996) to validate the accuracy of the turbulenc e model and numerical method. The computational results match well with the experimental data. Circumferential local friction factors and Nusselt numb ers are presented. These results indicate that spiral fins deliver 37% to 5 0% of the total heat transfer, and the pressure resistance from the leeward and windward sides of the fins is about 30% to 44% of total friction resis tance.