Numerical investigation of the effect of winglets on flow and heat transfer in hybrid corrugated channels

In this study, the effect of winglets on the flow and heat transfer in hybrid wavy channels is investigated numerically. The numerical study was carried out with the ANSYS Fluent program based on Computational Fluid Dynamics (CFD). The velocity and pressure relationship in the transport equations was solved by the SIMPLE algorithm. Firstly, the flow and heat transfer of hybrid wavy channels without winglets were investigated in the study. Hybrid wavy channels consist of three different wave profiles consisting of triangular, trapezoidal and circular geometries added to the rectangular wave profile. Thus, three different hybrid wavy channel designs including rectangular-triangular (DU), rectangular-circular (DD) and rectangular-trapezoidal (DT) profiles were considered. The results were compared with the rectangular wavy channel flow. The surfaces of the wavy channels were kept at a constant temperature (Tw = 380K) and the Reynolds number was varied in the range of 2000 ≤ Re ≤ 10000. For each hybrid channel design, the flow and heat transfer characteristics were analyzed and the Nusselt number (Nu), friction factor (f), pressure drop (𝛥P) and performance factor (PF) were calculated. The results showed that the best performance factor was provided in the rectangular-trapezoidal (DT) hybrid corrugated channel. Therefore, three different winglets, namely V type, Y type and V-Y type (hybrid type), were placed in the DT hybrid channel and their effects on the flow and heat transfer were analyzed. In the analyses, when the flat channel without winglets was compared with the DT-hybrid corrugated channel, Nu increased by approximately 4.9 times while the pressure drop increased by approximately 15.8 times. The hybrid corrugated channels provided higher heat transfer without a significant increase in pressure drop compared to the uniform rectangular corrugated channel. In the presence of winglets, the highest heat transfer was obtained in the DT hybrid wavy channel with V-type winglets (Nu = 73.90), while the lowest pressure loss was observed in the channel with Y-type winglets (ΔP = 259.39 Pa). The best performance factor (PF) was found in the DT channel without winglets (PF = 2.95), while in the channel with winglets, the PF tended to decrease with the increase in Reynolds number. The findings show that in channels to be designed considering both heat transfer and flow resistance, the winglet type and channel geometry should be evaluated together.