幂律流体同心环空内层流脉动流的数值分析

建立幂律流体环空内层流脉动流的数学模型,采用SIMPLE算法进行数值求解,得到幂律流体环空脉动层流的流动特性。结果表明:幂律流体环空脉动流的流动特性与稳态流动时差异较大;环空脉动流在距入口非常短的一段距离内就可达到充分发展,且不同时刻的入口段长度随时间而变化;低脉动频率下速度分布曲线类似于稳态时的抛物形分布,高频率下壁面附近的速度分布曲线发生扭曲,振荡速度的最大值出现在壁面附近;内、外壁面的摩擦系数和轴向压力梯度均近似满足正弦变化规律,脉动频率、振幅和流体流性指数的增加均会使壁面摩擦系数和轴向压力梯度及其变化幅度增大。

Numerical analysis of laminar pulsating flow for power-law fluid in concentric annulus

A mathematical model for laminar pulsating flow of power-law fluid in annulus was set up and solved by SIMPLE method.The results show that the flow behavior of pulsating flow is quite different from that of steady flow.Fully developed lamilar flow can be achieved in a small distance from the annulus entrance,and the hydrodynamic entrance length varies with time.The transient pulsating velocity curve at low pulsating frequency is similar to parabolic distribution of steady flow.The influence of pulsation is distinct at high frequency and the maximum oscillating velocity component appears near the wall.The wall friction coefficient and the axial pressure gradient vary with time approximately in sinusoidal manner.The friction coefficient at inner and outer wall and the axial pressure gradient and their variation range all increase with the increase of pulsating frequency,amplitude and the flow index of fluid.