脉动作用下波壁管内非牛顿流体流动特性的研究

在热量和质量传递过程中，流体的流动状态对整个传递过程有着重要的影响，为此，通过实验方法对以聚丙烯酰胺（PAM）溶液为代表的非牛顿流体在波壁管内的流动特性进行压力差和可视化研究。研究发现，PAM溶液存在一个最佳减阻浓度，在该浓度下与牛顿流体相比PAM溶液的转捩点明显提前。此外在脉动流场下，在一个脉动周期内，波壁管内流体存在明显的稳定流动和不稳定流动两种结构；相同净雷诺数条件下，脉动流场下波壁管内流体的流动混合情况比定常流动状态下强烈很多，意味着脉动流场具有更加优越的质量传递特性。

Characteristics or flow of non-Newtonian fluid in a wavy-walled tube for pulsatile flow

The flow state has important impact on the heat and mass transfer. Hence pressure differences and flow visualization experiment were carried out in a wavy-walled tube with polyacrylamide solution, which is a kind of typical non-Newtonian fluid, for pulsatile flow field. Compared with water, the moderate concentration of polymer solution can reduce the frictional resistance and natural transition Reynolds number. Stable and unstable states of flow patterns are found in wavy-walled tube during one oscillation cycle. Based on the experimental results, the fluid mixing under the conditions of pulsating flow is better than under the conditions of steady flow at the same net Reynolds number, which means that mass transfer have been enhanced significantly under the conditions of pulsating flow.