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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(6000~30000)、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。与传统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。
In order to achieve uniform and efficient jet impact cooling, a new type of swirling jet cooling structure is proposed, that is, four spiral grooves with equal screw holes at equal intervals on the inner wall of the circular hole. The experiments were carried out to study the effect of the nozzle on the target surface under the conditions of different helix angle (0 °, 15 °, 30 °, 45 °), Reynolds number Re (6000 ~ 30000) and impact distance (1 ~ 8 times equivalent diameter) Thermal characteristics of the impact of jet nozzle surface reveals the heat transfer law. The experimental results show that the heat transfer coefficient of the target surface is increased with increasing the angle of the helical groove. Compared with traditional circular holes and non-rotating multi-channel impinging jets, the rotating jet with a certain helix angle can effectively improve the overall heat transfer coefficient of the target surface. At 2 times and 4 times the equivalent diameter of the impact distance, the Nusselt number N0 of the rotational position of the 45 ° -type screw hole swirling jet was 7.4% and 11.4% higher than that of the ordinary circular jets, respectively. The target surfaces Nu and Re Which is a nonlinear proportional relationship. At high Re, Nu peaked at 0.7 times equivalent diameter outside the center of the target surface. As the impact distance increases, the effect of swirling on the target surface heat transfer decreases or even disappears.