摘要
为了实现均匀高效的射流冲击冷却,提出了一种新型旋流射流冷却结构,即圆孔内壁等间隔设有4条类似螺纹孔的螺旋槽道。通过实验研究了该喷嘴在不同螺旋角(0°、15°、30°、45°)、雷诺数Re(6 000~30 000)、冲击距离(1~8倍当量直径)等参数下对靶面换热特性的影响,揭示了该喷嘴冲击射流靶面的换热规律。实验结果表明,增大螺旋槽道角度,靶面的换热系数有所增强。与普通圆孔及无旋多槽道冲击射流相比,同工况下带有一定螺旋角的旋转射流可有效提高靶面的整体换热系数。在2倍和4倍当量直径的冲击距离下,45°类螺纹孔旋流射流换热的驻点努塞尔数Nu比普通圆孔射流分别高出7.4%和11.4%;靶面Nu与Re成非线性正比关系,在较高Re下Nu在靶面中心点以外0.7倍当量直径处出现峰值;随着冲击距离的增大,旋流对靶面冲击换热的作用效果减弱,乃至消失。
To achieve high efficiency cooling performance and good uniformity of impinging jet,a new type of nozzle structure is proposed.The new nozzle has four circumferential spiral channels symmetrically distributed inside a normal smooth nozzle,similar to an internal threads.The influences of this nozzle on heat transfer characteristics of impinged surface under different helix angles(0°,15°,30°,45°),Reynolds numbers(600030000)and impact distances(1to8times the equivalent diameter)were studied experimentally.And the heat transfer rule of the impinged surface was revealed.The experimental results indicate that a big helix angle can enhance slightly the heat transfer coefficient on the impinged surface.Compared with the conventional impinging jet from the smooth circular hole and the hole with four straight channels,the swirling impinging jets from the designed nozzles are effective to enhance the overall heat transfer coefficient on the impinged surface under the same conditions.At the impact distances of2times and4times the equivalent diameter,Nusselt numbers of the45degree thread hole are74%and114%higher than that of conventional impinging jet at the stagnation area,respectively.The heat transfer coefficient on the impinged surface is non linearly increased with the increase of Reynolds number.The maximal value of Nusselt number under a relative large Reynolds number occurs at the location of07times the equivalent diameter outside the stagnation point.With the increase of the impact distance,the effect of the swirling flow on the target surface heat transfer is weakened or even disappeared.
作者
兰进
徐亮
马永浩
高建民
李云龙
LAN Jin;XU Liang;MA Yonghao;GAO Jianmin;LI Yunlong(State Key Laboratory of Mechanical Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, China)
出处
《西安交通大学学报》
EI
CAS
CSCD
北大核心
2018年第1期8-13,76,共7页
Journal of Xi'an Jiaotong University
基金
陕西省自然科学基础研究计划资助项目(2015JQ5126)
关键词
旋流冲击射流
冲击冷却
换热均匀性
螺纹孔
swirling impinging jets
impingement cooling
uniformity of heat transfer
thread nozzle
作者简介
兰进(1987—),男,硕士生;通信作者:徐亮,男,副教授
