关键词: 螺旋喷嘴, 射流冷却, 湍流模型, 换热效率

Abstract:  Using ANSYS FLUENT software and RNG k-ε turbulence model, the internal flow characteristics and coupling surface heat transfer characteristics of spiral nozzles with cross-shaped, inner cross-shaped and flower-shaped structures were studied respectively. The numerical results show that the smaller the helix angle θ is, the higher the outlet velocity of the spiral nozzle is, the more concentrated the water flowing out of the nozzle is, and the clearer and more obvious the water movement track is. Under the same working condition, the heat transfer efficiency and heat transfer uniformity of flower-shaped nozzle with the helix angle 30° are higher than those of the two other nozzles. The maximum position of Nusselt number Nu of its coupling surface would gradually be away from the jet center (r/d_j=0, d_j is the equivalent diameter of nozzle) with the increase of Reynolds number Re. With the increase of target distance H, Nu gradually decreases and the swirling effect gradually weakens. When H=2d_j, 4dj, the maximum Nu is located at r/d_j=1, and when H=6d_j, the maximum Nu is located at the jet center (r/d_j=0). 

Key words:  Spiral nozzle, Jet cooling, Turbulence model, Heat transfer efficiency