Numerical Study on Wake Flow of Curved Tube Affecting the Thermal Performance of a Downstream Tube in Crossflow of Air

ABSTRACT Three‐dimensional numerical study was conducted to investigate the thermal performance and the wake interaction of different combinations of an upstream curved tube and a downstream straight tube in tandem arrangement in cross flow of air at a Reynolds number of 35,000 The curvature ratio of the upstream tube, configuration of the tube, that is, concave and convex and the centre‐to‐centre pitch ratio between the tubes were the independent variables while the resulting flow structures, wake interference patterns, local and average Nusselt numbers, and Goodness factor were evaluated as dependent performance metrics. The key objective was to evaluate the influence of geometric and flow parameters on heat transfer enhancement which is used in compact heat exchanger for food manufacturing applications. The curvature ratio of curved tubes and pitch ratio was varied from (0.5 to 1.5) and (1.5 to 4.0) respectively; resulting in different combination of curved‐straight tubes. The results illustrate different flow regimes based on different pitch ratios and identifies that most combinations of curved and straight tubes results in enhanced heat transfer with the maximum share of heat transferred by the frontal portion of tube. For same PR and CR, the study reveals that the convex curvatures are more effective in heat transfer compared to the concave ones. Most of the combinations have Goodness Factor greater than unity which shows that thermal performance of combination of tubes exceed the hydraulic penalty.