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 

摘要： 使用 ANSYS FLUENT 软件和 RNG k-ε 湍流模型分别研究了十字形、内十字形和花形结构的螺旋喷 嘴内部流动特性和耦合面换热特性。模拟结果研究表明，螺旋角 θ 越小喷嘴出口速度越高，喷出的水流更集中， 水流运动轨迹越清晰且规律越明显。同一工况下，θ=30°的花形喷嘴的换热效率和换热均匀性均优于其余两种喷嘴的值；耦合面努塞尔数 Nu 最大值会随着雷诺数 Re 不断增加而逐渐远离射流中心处(r/d_j=0，d_j 为喷嘴当量直径)； 随着靶距 H 逐渐增大，Nu 逐渐减小，旋流效果逐渐减弱。当 H=2d_j、4d_j 时，Nu 最大值位于 r/d_j=1 处；当 H=6d_j 时，Nu 最大值位于射流中心处。

关键词: 螺旋喷嘴, 射流冷却, 湍流模型, 换热效率