管流转捩对比态定律的讨论——层、紊流并存流态转捩现象

Discussion on the Frictional Law of Corresponging State of the Transition in Passage ——the Coexistence of Laminar and Turbulent Flows

转捩对管内流动和换热有很大影响，Ｎ．Ｔ．Ｏｂｏｔ曾在总结归纳圆管、矩形管、三角形管和环形管实验结果的基础上提出对比态定律，并断言：对任意截面管道，只要知道临界摩擦因子和临界雷诺数，根据对比态定律，就可以计算其流动和平均换热特性。本文通过对复杂截面通道流动的研究，指出管流转捩的对比态定律只适用于单一流态管流，而不适用于层、紊流并存管流，文中还分析了层、紊流并存现象及其产生的原因，它的起始点和终止点的判定，以及流动和换热特性计算的处理方法。

The transition of the flow in passage has a considerable effect on the flow and heat transfer characteristics.N.T.Obot presented the frictional law of corresponding state based on the deduction of the experimental data for the circular, rectangular, triangular and annular passages. He stated that in accordance with the frictional law of corresponding state, the flow and heat transfer characteristics can be calculated by knowing the critical friction coefficient and the critical Reynolds number. However, this law is not applicable for the flow in complex sectional passage where the laminar and turbulent flows are coexistent. In this study, the phenomenon of the coexistence of the laminar and turbulent flows has been observed and the cause for the coexistence of the laminar and turbulent flows has been analyzed.The positions where the coexistence of the laminar and turbulent flows starts and ends have been evaluated. The methodology of treating the calculation of the flow and heat transfer characteristics for the laminar and turbulent coexistent flow has also been presented.