Numerical analysis of heat transfer intensity from twin slot vertical jet impingement on strip surface after hot rolling

Abstract

The flow field and heat transfer of the strip surface due to the twin slot vertical jet impingement were investigated using the ANSYS FLUENT. The RNG k-ɛ model was carried out in the turbulent calculation. Systematic parametric research was conducted by varying the jet velocity of nozzle exit (V=5 m/s, 7.5 m/s, 10 m/s), the temperature of cooling water (T_w=280 K, 300 K), the normalized spacing from the nozzle to the strip surface (H=10, 15, 20, 33), and the normalized spacing from the nozzle to nozzle centerline (W=0, 15, 30). The velocity streamline of the flow domain and the general trend of the distribution of the local Nusselt number on the impingement surface of strip were obtained. The result indicate that, the average Nusselt number increases by about 70% (90%) as the jet velocity is increased from 5 m/s to 7.5 m/s (from 7.5 m/s to 10 m/s), and T_w, H and W have minimal effect on it. While the valley Nusselt number decreases by about 10%–43% with the increase of H and W. The functional relationship between the average Nusselt number and the systematic parameters is derived by the least square regression method.

Keywords

ultra-fast cooling / heat transfer / flow field / twin slot nozzle / Nusselt number

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