竖直椭圆管内降膜波动的实验研究

EXPRIMENTAL STUDY OF WAVES ON FALLING FILM INSIDE A VERTICAL ELLIPTIC PIPE

一、前言 降膜流动广泛出现在化工,动力,制冷等工业设备中,它的流动特性对传热传质过程有很大影响。多数情况下,各种降膜表面都会有波动产生,这是导致努谢尔特理论解与实验结果不符的主要原因之一。对倾斜平板上降膜的理论与实验研究目前进行的较多。但对类似椭圆管表面存在周向表面张力梯度,具有横向流动的降膜波特性则研究的较少。本文采用电阻法测量了竖直椭圆管内降膜的波动特性。

The characteristics of wavy falling film flow inside a vertical elliptic pipe were measured with electrical conductivity method. The results show that there are two groups of waves with high and low frequency respectively. Waves always undergo a developing and/or damping processes. The frequency, amplitude, celerity and wavelength of waves are the function of Re number and the travling distance.