气液两相流压力波动特性

压力波动是两相流动的固有特性，研究波动规律对实现两相流动的智能监测有重要意义。本文采用统计学原理和确定性混沌学中的分形理论，对垂直上升空气水两相流的壁面静压力波动过程进行了研究，分析了表观液速对统计特征和分形特征的影响规律，首次发现环状流内高气速时压力波动的分维数大于1．5。

Pressure fluctuation for air-water two-phase flow

The phenomenon of pressure fluctuation is a natural feature of air-water two-phase flow. The measured fluctuation contains a great deal of information about the flowing mixture which can be used to diagnose process and meter problems from the analysis. In the present paper, the measured fluctuation of the static pressure in air-water two-phase flow in the upward section of a U-typetube is analyzed by means of statistical and freactal theories. The effect of liquid velocity on the fractal feature is investigated. Some highlights are obtained as follows. The power spectrum density (PSD) of the fluctuation has close relationship with flow regime, and the PSD exhibits a broad band of frequency and has a power-law falloff by visual inspection, which indicates that the pressure fluctuations may have chaotic behavior. The variations of root mean square vs. air velocity can show the change of flow regime in the case of low liquid velocity. The fractal dimension, correlation dimension and Kolmogorov entropy have close relationship with flow regime. It is found for the first time that the fractal dimension will be greater than 1.5 when the flow is annular with high gas velocity.