To improve the uniformity of traditional impinging jet heat transfer,a new type of jet structure with some circumferential spiral channels set inside the normal nozzle,like the internal thread,is proposed in this paper.First,several numerical methods are adopted to process the experimental data of the swirling impinging jet from a swirl generator,and the data are referenced from a published literature.Results show that the RNG k-ε turbulence model is more suitable for simulation of the swirling impingement jet.Then,the effects of such parameters as Reynolds number (4 000-12 000),impact distance (1-8 times of equivalent diameter) and helix angle (0°-75°) on the heat transfer performance of such threaded hole are studied.The research is focused on the flow field and heat transfer characteristics.The experimental results indicate that the heat transfer rate and the uniformity of impinging target will increase with the Reynolds number,and the local Nusselt number will increase first and then decrease with the increasing impact distance.Meanwhile,the double-peak feature of the local Nusselt number will change to single-peak shape,and the maximum local Nusselt number can be obtained at the 4-fold equivalent diameter.The local Nusselt number at the center point will increase with the helix angle,but the heat transfer uniformity will be worse.In addition,it is found that the helix angle corresponding to the best heat transfer performance also changes with different impact distances.%为了提高传统圆孔射流换热的均匀性,提出了一种新型的射流孔结构,即在普通圆孔周围设置螺旋槽,类似于内螺纹,并基于已有文献中的一种置入螺旋杆喷嘴的旋转射流实验数据,发展了一种采用RNG k-ε湍流模型的旋转射流传热数值计算方法.采用该方法,研究了雷诺数(4 000～12 000)、冲击距离(1～8倍当量直径)、螺旋角(0°～75°)等参数对所设计的螺纹孔旋转射流传热的影响.数值结果表明:提高雷诺数可以有效提高换热效率,并且能获得良好的换热均匀性;随着冲击距离的增大,旋转射流的局部努塞尔数先增大后减小,双峰值特性逐渐消失并转变为单峰值特性,在4倍当量直径的冲击距离时,换热系数达到最大值;随着螺旋角增大,中心点的局部努塞尔数也随之增大,同时换热均匀性会变差.研究还发现,不同冲击距离下换热性能最佳时对应的螺旋角也不同.
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