Numerical evaluation of the heat transfer enhancement in a tube with a curved conical turbulator insert

A three-dimensional numerical evaluation is presented to investigate the effect of inserting a curved innovative turbulator on heat transfer improvement in a pipe. The investigated curved nozzle has several rows of flow directors to create turbulent swirl flows. Five geometrical parameters, including angle of curvature, diameter of flow director, cone angle, nozzles outlet diameter and flow director number, are studied in the range of Reynolds numbers 10,000–35,000. Results indicate that the outlet diameter of the conical nozzle has an insignificant effect on thermal performance. Also, the heat transfer and thermal performance are higher with a higher number of flow director rows. Moreover, as the angle of curvature increases, due to the growth in the secondary flows, average Nusselt number rises. However, the case with a curved proposed turbulator shows lower thermal performance compared to the uncurved one because of a major pressure drop. Maximum average Nusselt number belongs to the case with d = 7 mm as the optimum value.