Numerical investigations on the heat transfer characteristics of pin-fin heat sink for power converters in more electric aircraft

Efficient cooling of high-power density converters is critical for the aerospace industry. This study investigates a 40-kW aviation power converter and examines the heat transfer (HT) characteristics of pin-fin heat sinks under specific operating conditions. The effects of the height-to-diameter ratio (r_h), relative spanwise spacing (r_s), relative streamwise spacing (r_x), and Reynolds number (Re) on HT performance are analyzed. When the pin-fin diameter is fixed, the average Nusselt number (Nu¯) of the pin-fin surface (PFS) is consistently 40 %–70 % higher than that of the end wall. Both Nu¯ levels on the PFS and end wall increase as Re increases. The thermal performance index (TPI) and improved thermal performance index (TPI’) both initially increase and then decrease with increasing r_h when Re ≤ 10,000, while they consistently decrease with increasing r_h when 15,000 ≤ Re≤25,000. Additionally, the friction coefficient and resistance enhancement coefficient increase as r_h varies from 4 to 20. The optimal heat sink structure is identified as having a pin-fin diameter of D = 6 mm, a height-to-diameter ratio of r_h = 10, a relative spanwise spacing of r_s = 3, and a relative streamwise spacing of r_s = 3 and r_x = 2.5, respectively.