Behavior of Air-liquid Surface Moving Downward in a Straight Pipe

抄録

In this paper an experimental study on the behavior of the air-liquid surface in various vertical and circular pipes is described. The case when a liquid piston is suddenly started from a vertical pipe which is previously filled up with a liquid and pressurized air on the top, is examined. It is known that the measured velocity of the tip of the surface agrees approximately with the simplest one dimensional model, and the shape of the surface is divided into two areas ; one is flat shape for the case of nearly constant velocity, and the other is spherical shape accompanied with an accelerating velocity. And further, the effects of an obstacle on the wall on the air-liquid surface behavior are obserbed, and it is found that sometimes a turbulence appears on the surface and grows up sharply, and the condition for the growth of the disturbance depends on Reynolds number and stability number.