The present study investigates the heat transfer characteristics of swirling coaxial confined impinging turbulent air jets. Experimental range covers different values of dimensionless nozzle-to-plate distance (H / D = 0.5, 1 and 2) and dimensionless flowrate ratio (Q* = 0.2 and 0.5). The total flowrate is kept constant at 1.16 x 10-3 m3 s-1 (70 L/min) during the tests. The results are also compared to those obtained for the conventional single circular jets (Q* = 0). It is concluded that both the intensity and the radial uniformity of the heat transfer are improved by increasing dimensionless flowrate ratio. On the other hand, increasing nozzle-to-plate distance causes a decrement in the magnitude of Nusselt numbers.  

Keywords - Impingement, swirling jet, coaxial, heat transfer, radial uniformity

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