Impact of Leading and Trailing‐Edge Perforations on the Thermohydraulic Performance of Rectangular‐Winglet Vortex Generators

In this study, the thermohydraulic performance of rectangular‐winglet vortex generators (VGs) with different hole configurations (a central hole, dual‐edge holes, a leading‐edge hole, and a trailing‐edge hole) was numerically investigated. In addition, airflows through solar air heater ducts enhanced with these VGs were simulated using the realizable k‐epsilon model with a wall function at Reynolds numbers (Re) from 3000 to 20,000 and a Prandtl number ( P r ) of 7.070. A constant blockage ratio, defined as the ratio of the VG surface area to the cross‐sectional area of the airflow duct, was maintained. Overall, the results showed that the VG with a trailing‐edge hole achieved the highest thermal enhancement factor (TEF), ranging from 1.394 to 1.600. The central‐hole VG exhibited slightly lower TEF, between 1.424 and 1.578. In contrast, the dual‐edge‐hole and leading‐edge‐hole VGs produced lower TEFs, ranging from 1.301 to 1.541 and 1.282 to 1.567, respectively. Several temperature distribution plots, velocity plots, and pathline plots were utilized to investigate the cause of the performance differences. These visualizations ultimately revealed that the observed variations in thermohydraulic performance were attributed to distinct flow structures induced by the different hole configurations and Re values. In light of these findings, it can be concluded that the trailing‐edge‐hole VG is the most preferred option, while the central‐hole VG serves as a viable alternative, offering nearly equivalent performance. In contrast, the leading‐edge‐hole and dual‐edge‐hole VGs are less efficient and not recommended.