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本文用Mach-Zehnder干涉仪对置于空气中水平方形柱体的大空间自然对流换热进行了系统的实验研究.得到了柱体底面与水平线成各种倾角下的温度场;整理了不同倾角下平均Nu数随Ra数变化的关系式;分析了底面倾角对整体换热影响的机理,得出了倾角等于45°时换热最强的结论;分析了不同倾角下局部Nu数沿壁面变化的原因,尖角对换热的影响.并对自然对流流动分离进行了探讨,认为方形柱体在各种倾角下,Ra数超过一定值时,均会产生流动分离,分离的可能性随Ra数的增高而加大.
In this paper, we use the Mach-Zehnder interferometer to systematically study the natural convection heat transfer in a large space of horizontal square cylinder in the air, and get the temperature field under various inclinations of the bottom and the horizontal of the cylinder. The relationship between the average Nu number and the Ra number is analyzed. The mechanism of the effect of bottom dip on the overall heat transfer is analyzed. The conclusion that the heat transfer is the strongest when the dip angle is equal to 45 ° is obtained. , The influence of sharp corners on heat transfer was discussed, and the separation of natural convection flow was discussed. It is concluded that the flow separation occurs when the Ra number exceeds a certain value under various inclinations, and the possibility of separation is similar to that of Ra Increase the number and increase.