Numerical Investigation of the Effect of a Pulsating Jet with Sister Holes on Heat Transfer in a Square Duct Flow

Efficient thermal management is essential for improving the reliability and energy efficiency of high-power electronics and high-temperature engineering systems. While film cooling is widely employed to protect components under severe thermal loads, passive methods like sister-hole configurations have attracted attention for their ability to improve coolant coverage and suppress jet lift-off. To address existing limitations, this study proposes a hybrid active-passive cooling strategy integrating a pulsating jet with sister holes in a square duct. The effects of blowing ratio (M=0.5-2), Reynolds number (Re=10000), pulsation amplitude (Ao=0.2 and 0.8), and non-dimensional frequency (Wo=4.6-13.1) on flow and heat-transfer characteristics were numerically investigated and validated against experimental data. The results show that the hybrid mechanism effectively modifies primary jet vortex structures, enhances coolant attachment, and promotes uniform thermal coverage. Compared with the steady baseline configuration, the proposed approach increased heat transfer by up to 33%, with the maximum enhancement achieved at a high pulsation amplitude (Ao=0.8) and low non-dimensional frequency (Wo=4.6), demonstrating the potential of synergistic flow control.