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

1.本文从实验和理论上研究了径向自由液膜流动的层流-湍流转捩。这种流动是通过在水平放置的圆盘上沿着形成一层薄的径向液膜并使其流入大气中而产生的。使用频闪仪观察到的过渡机制。用LDV测量了厚度约为0.2mm的自由液膜中的速度分布。用线性稳定性理论研究了这种转变现象。其结果是，在液膜内的涡量分布的不均匀性引起的过渡。2.本文对旋转圆盘径向液膜流动的层流-湍流转捩进行了实验研究。通过使水从水平放置的旋转盘和圆形喷嘴之间的圆柱形开口沿着盘的上表面沿着排放到大气中来产生流动。对转捩过程的高速观测表明，当周向速度相对于径向速度较小时，圆盘旋转抑制转捩，而当周向速度较大时，圆盘旋转促进转捩。

1. The laminar-turbulent transition in the radial flow of a free liquid film is studied experimentally and theoretically. The flow is generated by making a thin radial liquid film along a horizontally placed circular disk and letting it flow out into the atmosphere. The transition mechanism is observed using a stroboscope. The velocity distributions in a thin free liquid film having a thickness of about 0.2 mm are measured by LDV. The phenomena of the transition is investigated by means of the linear stability theory. As a result, the transition is caused on the nonuniformity of the vorticity distribution inside the liquid film. 2. The laminar-turbulent transition in the radial liquid film flow on a rotating disk is studied experimentally. The flow is generated by letting water discharge from a cylindrical opening between a horizontally placed rotating disk and a circular nozzle into the atmosphere along the upper surface of the disk. The high speed photographes of the process of the transition show that, while the rotation of disk suppresses the transition as long as the circumferencial velocity is relatively small to the radial velocity, it promotes the transition when the circumferencial velocity becomes large.