Heat Transfer Enhancement via Dual Coaxial Swirling Jet Impingement Configurations

This study numerically investigates dual coaxial swirling jet impingement on a flat surface using ANSYS FLUENT with the Shear-Stress Transport (SST) [Formula: see text] turbulence model in a two-dimensional axisymmetric domain. Three jet configurations ([Formula: see text], [Formula: see text], and [Formula: see text]) are examined across Reynolds numbers of 10,000, 16,000, and 23,000; nozzle-to-target spacings ([Formula: see text]) of 2, 4, and 6; and swirl intensities of [Formula: see text] under both uniform heat flux (UHF) and constant-temperature boundary conditions. A novel mathematical formulation for the swirl number in dual-jet systems is introduced. The results reveal that swirl significantly enhances heat transfer, particularly at lower nozzle-to-target spacings. Swirl-induced centrifugal forces promote axial-to-radial momentum conversion, generating vortex rings, recirculation zones, and negative pressure regions. At [Formula: see text], [Formula: see text], and [Formula: see text], configuration [Formula: see text], which combines a swirling inner jet with a nonswirling annular jet, increases the peak Nusselt number by up to 147% relative to the nonswirling baseline. Although swirl reduces peak Nusselt number and pressure coefficient, both increase with Reynolds number and decrease with nozzle-to-target spacing. Configuration [Formula: see text], combining inner jet swirl with a nonswirling annular jet, consistently outperforms all other configurations, demonstrating the thermal benefits of optimized swirl intensity in impingement cooling applications.