局部狭窄圆管的形态与流动分离区域的关系

Relations Between the Regions of Flow Separation and the Shape of Local-Restricted Cylinder

采用局部狭窄管内流体流动的Karman-Pohlhausen改进理论,提出了用压强参量的二次方程实根确定狭窄区域流动分离的判别式.选取不同的局部狭窄形状和流动参数,对判别式的计算结果表明,随雷诺数的增加,流动分离和再附着现象首先出现在狭窄管的舒张区,然后在收缩区也会逐渐产生.在舒张区域,随雷诺数的变化,理论计算的初始分离点、分离和再附着点更接近已有的实验结果.

Based on the theoretical improvement of the Karman-Pohlhausen＇s method of fluid flow in the local-restricted cylinder, the criterion of flow separation can be obtained from the discriminant of quadratic equation for pressure parameter. The discriminant is calculated by selecting different local-restricted cylinder geometry and flow situations. The results show that with the increase of Reynolds number, the phenomena of flow separation and reattachment occur first in the diverging part of local-restricted cylinder, subsequently in the converging part. In the diverging part, theoretical values of initial separated point, separation and reattachment points vary with Reynolds number and are more consistent with the past experimental results.