不同结构的条缝喷嘴对冲击射流换热的影响

Effect of Slit Nozzles of Different Structures on the Heat Transfer of Impinging Jets

本文采用数值模拟结合实验验证的方法,对比了170 Pa和190 Pa两种进口压力条件下,3种不同结构的V型条缝喷嘴对冲击式速冻设备换热的影响,分别从喷嘴出口风速、横流方向风速以及努塞尔数(Nu) 3个方面进行研究分析。结果表明:喷嘴延伸段长度K较大的喷嘴出口风速较大、流场较为均匀,但较大的K反而削弱对流换热的强度;喷嘴渐缩段与延伸段之间的夹角α较小的喷嘴在横流方向上的风速较小、均匀度较高,受横流影响较小,但对提高对流换热强度的作用不明显;当V型条缝K=10 mm,α=165°时,平均Nu最高,对流换热的强度最大。

In this study,the effects of three types of V-shaped slit nozzles of different structures on the heat transfer of impingement quick-freezing equipment under 170 Pa and 190 Pa pressure conditions are compared by both numerical simulation and experiment. The outlet wind velocity,cross flow wind velocity and Nussel number(Nu) are investigated under different conditions. The results show that the nozzle outlet with a longer K,nozzle extension length,has a higher wind speed and more uniform flow field. However,the longer K will weaken the convective heat transfer intensity. The nozzle with a smaller angle α between the nozzle shrinking and extension sections has a lower wind speed and higher uniformity in the transverse flow direction and is less affected by the transverse flow;however,it has no obvious effect on improving the convective heat transfer intensity. When the length of the K of the V-shaped slit nozzle is 10 mm and the angle α between the nozzle contraction and extension sections is 165°,the average Nu and the convective heat transfer intensity are at a maximum.