摘要
雾化形成液膜的传热系数与厚度是决定喷雾冷却效果的重要因素。采用数值模拟方法,基于加热壁面上的液膜厚度、传热系数与温度分布三个角度,分析喷雾的压力、高度与倾斜角度对喷雾冷却传热特性的影响。结果表明:喷雾压力是影响换热效果重要的因素。相比于低压力工况,高压力工况时壁面上形成的液膜厚度小,壁面平均温度低,换热能力较强。压力工况越大,壁面温度下降程度越高。主要因为喷射压力提高后,液膜的运动速度加快,导致与空气之间的扰动作用加强,促进了液膜破碎和液滴的形成。改变高度使喷射到壁面的液滴密度程度不同,导致温度分布不均匀。研究还发现喷雾高度对换热影响存在一个最优值,H=6 mm时,换热效果最好。同样,改变倾斜角度导致壁面分为喷雾密集区跟稀疏区,换热效果区别大。喷雾倾角θ=30°时壁面换热效果最好且温度分布相对均匀。通过分析得到的变化规律为喷雾参数的设定和喷雾效果的优化提供了理论依据。
The heat transfer coefficient and thickness of the atomized liquid film are important factors in determining the spray cooling effect. The numerical simulation method is used to analyze the effect of spray pressure,height and tilt angle on the heat transfer characteristics of spray cooling based on three angles of liquid film thickness,heat transfer coefficient and temperature distribution on the heating wall. The results show that the spray pressure is an important factor affecting the heat transfer effect. Compared with the low pressure working condition,the liquid film formed on the wall surface is small in the high pressure working condition,the average wall temperature is low,and the heat exchange capacity is strong. The greater the pressure condition,the higher the wall temperature drop. Mainly because the injection pressure is increased,the movement speed of the liquid film is increased,resulting in a strong disturbance between the air and the air,which promotes liquid film breakage and droplet formation. The height is changed so that the density of the droplets ejected to the wall is different,resulting in uneven temperature distribution. The study also found that there is an optimal value of the effect of spray height on heat transfer. When H=6mm,the heat transfer effect is best. Similarly,changing the angle of inclination causes the wall to be divided into a spray-intensive area and a sparse area,and the heat exchange effect is largely different. When the spray angle *30°,the heat transfer effect of the wall surface is best and the temperature distribution is relatively uniform. The variation rule obtained by the analysis provides a theoretical basis for the setting of the spray parameters and the optimization of the spray effect.
作者
吴正人
甄猛
刘梅
王松岭
刘秋升
WU Zhengren;ZHEN Meng;LIU Mei;WANG Songling;LIU Qiusheng(College of Energy Power and Mechanical Engineering,North China Electric Power University,Baoding 071003;Department of Economics and Management,North China Electric Power University,Baoding 071003)
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2019年第4期172-180,共9页
Journal of Mechanical Engineering
基金
高等学校博士学科点专项科研基金(20110036110009)
河北省自然科学基金(E2016502088)资助项目
关键词
传热
液膜厚度
传热系数
计算流体力学
数值模拟
heat transfer
liquid film thickness
heat transfer coefficient
computational fluid dynamicsCFD
numerical simulation
