Effect of Streamwise Spacing on the Flow and Heat Transfer of Lantern-shaped Pin Fins in a Rectangular Channel

Understanding the flow and heat transfer characteristics of pin fin arrays, which are widely used as cooling structures for electronic devices and turbine blades, is essential for cooling design. Focusing on the impact of streamwise spacing on the flow and heat transfer of pin fins in a rectangular channel, this study conducts a numerical analysis and compares of the changes in flow field, Nusselt number, and pressure drop for lantern-shaped pin fins with two sphere diameters and four streamwise spacings in the Re range of 3,000 to 30,000. For both types of pin fins with different diameters, reducing the streamwise spacing results in an increase in the turbulent kinetic energy. The lantern-shaped pin fin enhances the turbulent mixing level closer to the endwall as compared to the circular-shaped pin fin. As the streamwise spacing decreases, the area-averaged endwall, pin Nusselt numbers and friction factor increase. The thermal performance index of the circular-shaped pin fin increases with increasing streamwise spacing. At Re=3,000, the thermal performance index of the lantern-shaped pin fin exhibits a trend of initially decreasing and then increasing. It always decreases when 5,000<Re<15,000. When Re>20,000, there is an initially increasing and then decreasing in its trend.