大曲率弯道中拟塑性流体的湍流数值计算研究

Numerical Study of Turbulent Flows of a Pseudoplastic Fluid in a Strongly Curved Square Duct

本文采用一种耦合流体流变性的修正的低雷诺数k-ε模型,结合前期建立的适用于拟塑性非牛顿流体的高精度算法,数值模拟研究了90°大曲率方截面弯道中拟塑性流体的湍流流动,并与实验数据进行比较。结果表明,主流速度的预测值与实验结果呈现出较为一致的分布趋势,表明了方法与模型的有效性。在弯道及其下游平直恢复段,拟塑性流体湍流的脉动动能最大值均出现在弯道的侧壁附近。而在弯道的下游恢复段,轴向和径向湍流脉动强度在从截面中心到弯管外壁的方向上分布呈现出先减小后增大的趋势。

This paper presents a numerical study of the turbulent flows of a pseudoplastic fluid in a strongly curved square duct.The fluid rheology is introduced to modify the low Reynolds number k —ε model and an in-house code using high-order finite volume method is adopted for numerical computation.The calculated results show that distributions of the longitudinal velocity in cross-sections generally agree well with the experimental data.In the curved and downstream cross-sections of the duct,the peak values of the turbulent kinetic energy are observed close to the side walls.Different from the Newtonian fluids,for the levels of axial and radial turbulent fluctuations for the pseudoplastic fluid in the cross-sections in the downstream of the curved duct,their variation in the radial direction has a tendency of decrease firstly and then increase,from the cross-section centre to the outer wall of the duct.