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The effect of high-frequency oscillations on the disturbance waves in annular flow
International Journal of Multiphase Flow ( IF 3.8 ) Pub Date : 2021-07-15 , DOI: 10.1016/j.ijmultiphaseflow.2021.103754
Andrey V. Cherdantsev 1 , Sergey V. Isaenkov 1 , Mikhail V. Cherdantsev 1 , Dmitry M. Markovich 1
Affiliation  

In this paper, an analysis of susceptibility of wave structure in annular flow to small high-frequency oscillations is carried out. Downward adiabatic air-water flow at atmospheric pressure is studied in a vertical 11.7 mm pipe. The range of superficial gas velocities is 0 – 70 m/s and the range of wetting densities is 1.6 – 4.6 cm2/s. Spatiotemporal records of liquid film thickness are obtained with the Brightness-Based Laser-Induced Fluorescence technique. The region of interrogation is one longitudinal section of the pipe with a length of 470 mm, starting from the inlet. The oscillations are imposed by a solenoid-driven membrane causing periodic pulsations of liquid flow rate. The oscillation frequency range is 0 – 100 Hz. The amplitude of pulsations decreases with the oscillation frequency. The effect of oscillations is first tested on liquid films falling in absence of gas flow. In this case, the excited waves are of the same frequency as the imposed oscillations, and the stages of wave development are shifted closer to the inlet. In the case of liquid films under strong gas shear, the oscillations induce low-amplitude waves, which interfere with high-frequency initial waves, produced by the shear instability. Without excitation, groups of successive initial waves coalesce to produce the disturbance waves, which vary in speed and coalesce with each other. Within a certain range of excitation frequency, each period of low-amplitude wave produces one disturbance wave, so that coalescence nearly disappears and the waves become regular. Various criteria of susceptibility are proposed; the best ones are based on spectral analysis. The susceptibility range of excitation frequencies encompasses the ‘natural’ passing frequency of disturbance waves far downstream. The width of this range is of the order of 20 Hz but decreases at high frequencies when the amplitude of the pulsations decreases. Under excitation, the disturbance waves accelerate and grow in amplitude very fast, reaching saturated values near the inlet. The saturated values are not very different from the ‘natural’ ones. An increase in the excitation frequency within the range of susceptibility leads to a small decrease in the speed and amplitude of the disturbance waves. The entrained fraction shows only a minor increase due to the excitation.



中文翻译:

高频振荡对环流扰动波的影响

在本文中,进行了环形流中波浪结构对小高频振荡的敏感性分析。在一个 11.7 毫米的垂直管道中研究了在大气压下向下绝热的空气 - 水流。表观气体速度范围为 0 – 70 m/s,润湿密度范围为 1.6 – 4.6 cm 2/秒。使用基于亮度的激光诱导荧光技术获得液膜厚度的时空记录。询问区域是管道的一个纵向截面,长度为 470 mm,从入口开始。振荡由螺线管驱动的膜施加,引起液体流速的周期性脉动。振荡频率范围为 0 – 100 Hz。脉动的幅度随着振荡频率的增加而减小。首先在没有气流的情况下下落的液膜上测试振荡的影响。在这种情况下,激发波与施加的振荡具有相同的频率,并且波发展的阶段更靠近入口。在强气体剪切作用下的液膜情况下,振荡引起低振幅波,其干扰由剪切不稳定产生的高频初始波。在没有激励的情况下,多组连续的初始波合并产生扰动波,扰动波的速度不同并相互合并。在一定的激励频率范围内,每一周期的低幅波产生一个扰动波,使聚结几乎消失,波变得规则。提出了各种敏感性标准;最好的是基于光谱分析。激励频率的敏感范围包括远下游扰动波的“自然”通过频率。该范围的宽度约为 20 Hz,但当脉动幅度减小时,它会在高频处减小。在激励下,扰动波加速,振幅增长非常快,在入口附近达到饱和值。饱和值与“自然”值没有太大区别。磁化率范围内激励频率的增加导致扰动波的速度和幅度的小幅下降。由于激发,夹带的分数仅显示出很小的增加。

更新日期:2021-07-22
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