气液两相流中压力波动信号的混沌分析

对气液两相垂直向上并流中压力波动信号的混沌分析表明：外界噪声的干扰不可避免地会进入压力波动信号，从相空间内的吸引子图可明显地观察到噪声的存在，实验中采取多种手段，尽可能地把噪声的干扰降到最低极限，为提取反映系统特征的有效信息作前期准备。将预处理过的数据进行混沌分析得到，气液两相流的压力波动信号特征由两部分组成，低频部分（大气泡的运动或大尺度气液波动）和高频部分（如液体脉动、界面湍动等）。并且对应于不同操作条件下的流动体系，相关分维和Ｋｏｌｍ ｏｇｏｒｏｖ 熵均有较大变化，由此可区分流型。研究表明，对压力波动信号的混沌分析有助于深入理解系统的动力学特征。

CHAOTIC ANALYSIS OF PRESSURE FLUCTUATION SIGNAL IN THE GAS-LIQUID COCURRENT FLOW

Before further analysis, to extract information from the pressure fluctuation signals, the effect of noise should be minimized in this study experimentally. We reduced the noise as possible as it can be done through physical and digit filter. It was shown that there is a distinctive feature of the pressure signal by analyzing the chaotic characteristics of the pressure fluctuation signal from gas liquid co current up flow column. The feature was composed of two different parts: a low frequency part resulting from the motion of the large bubbles and a high frequency part resulting from all other processes (coalescence, collapse, breakup and strong pulsate) that take place in the column. At a same flow regime correlation dimensions change litter with liquid velocities growing. The correlation dimension and the Kolmogorov entropy as a function of velocity indicates a sharp transition from one regime to another. Therefore chaos analysis of pressure fluctuation signals could be believed to be a potential technique for on line identification of flow regimes.