高粘牛顿流体输送的表观滑移流动研究

On Drag Reduction from Apparent Wall Slip in Highly Viscous Newtonian Fluid Pipe Flow

在高粘度流体输送过程中,用低粘度的流体局部置换高粘度的流体,可以降低附壁边界层的粘性从而实现管道内流体流动减阻。对管道内两种粘度流体环状流动进行了理论和计算研究,推导了滑移层厚度及流体粘度与流动流量、减阻、滑移速度等的关系式,结果表明,随着滑移层变厚,其流速的增量会减小;当滑移层较薄时,流量增否取决于两层流体粘度之比;只有控制滑移层厚度不超过一定范围输送效率才会最大;滑移速度与压差成线性关系。

In the pipeline transport of highly viscous fluid, replacing viscous fluid with Newtonian fluid with lower viscosity around the pipe wall could reduce the shear stress in the wall boundary and lower fluid flow drag to save energy. Theoretical considerations and numerical evaluations are made in the paper with two viscosity pipe flows. Relations among thickness of low viscous layer (apparent wall slip layer),flow rate, drag reduction ratio, and apparent slip velocity are deduced. It is showed that drag reduction depends on the ratio of high and lower viscosity while low viscous layer close to a film,and flow drag could be negative or positive while the thickness of low viscous layer grows,and when the ratio of thickness of low viscous layer to pipe radius exceed a certain number,drag would be increased.