Abstract:

In order to understand the intrinsic mechanism of heterogeneity, non-linearity and chaotic behavior of fluid system in Kenics static mixer (KSM), the signals of tube-pressure fluctuation dynamics with different flow rates were collected with a high speed collector.Tube-pressure signals at different flow rates denoised by using the wavelet transform modulus maxima method were firstly decomposed to 1－7 scale detail signals and scale approximation and then evaluated by using multi-scale and R/S analysis method based on Daubechies second order wavelet.By analyzing the profiles of different scale signals, different fractal structures at different scales were found, and the similar trend of fractal structures with increasing flow rate was established.Besides, there were some non-periodic components in the system, and the similar energy exchange between particles caused the diffusion of turbulence, which was characteristic of an open system.The vortex with different scales would cause the chaos.The energy profiles of different scale signals indicated that pressure fluctuations mainly reflected the macro-scale interaction between vortex and liquid phase.

Key words:

静态混合器, 壁压波动, R/S分析, 多尺度, 多分形

摘要：

为了探讨静态混合器内非线性、非均匀性和混沌特性机理，利用高速数据采集系统对SK型静态混合器管壁处脉动压力进行测量。结合小波变换模极大值理论，对采集的不同进口流量下壁压波动时间序列用Daubechies二阶小波提取1～7尺度下的特征信号，并分别对提取的信号进行R/S分析。通过对压力波动信号不同尺度下的细节信号与概貌信号研究，发现在不同尺度下其表现出不同的分形结构，且随着进口流量的增大，分形结构的变化趋势基本一致。此外，该系统不仅存在确定性非周期成分，而且不同尺度的旋涡之间的能量交换导致混沌的产生。各尺度信号的能量分布表明，压力波动信号主要体现了宏观尺度的旋涡级串的相互作用。

关键词:

静态混合器, 壁压波动, R/S分析, 多尺度, 多分形