Laminar-Turbulent Transition in a Free Liquid Film Flow and Its Application to Liquid Atomization

1. 本文从理论和实验两方面研究了液膜沿旋转圆盘流动的层流-湍流过渡。流动具有一种三维边界层的速度分布。随着圆盘旋转对流动影响的增加，流动的不稳定性从粘性型转变为弯曲型。速度剖面的弱三维性导致扰动放大因子的减小，从而抑制了过渡，而强三维性则由于挠曲不稳定性而促进了过渡。实验研究了少量聚合物的加入对径向液膜流动转变的影响。研究发现，极少量聚合物的加入促进了这一转变。

1. The laminar-turbulent transition of a liquid film flow along a rotating disk is investigated both theoretically and experimentally. The flow has velocity profile of a kind of three-dimensional boundary layer. The instability of the flow changes, with an increase of the effect of the disk rotation on the flow, from a viscous- to an inflectional-type. The weak three-dimensionality of velocity profiles causes the decrease of the amplification factor of disturbance, suppressing the transition accordingly, whereas the strong three-dimensionality promotes the transition because of the inflectional instability.2. The influence caused by addition of a small amount of polymers on the transition in a radial liquid film flow were investigated experimentally. It was found that the addition of very small amount of polymer promotes the transition.