气液两相流多尺度相干结构及其间歇性

小波分析用于流体力学的研究已有一定的进展,采用恒温热膜测速技术,以高于对应的最小湍流时间尺度分辨率,精细的测量了鼓泡塔内不同空间位置的瞬时气液两相流动速度信号。基于子波系数的瞬时局部平坦因子,提出用子波分析检测湍流多尺度相干结构的条件采样方法,以单气泡结构的相位平均波形为基础,对鼓泡塔内气液两相湍流场进行了研究。结果表明:鼓泡塔中气泡结构是两相湍流产生奇异性和间歇性的诱因,喷嘴出口区域的一定喷射锥角范围内,才有气泡结构,并受到对应的平坦因子及间歇性的影响。

Multi-scale coherent structures and intermittency in-gas-liquid two-phase turbulent flow

This paper is concerned with the fine measurement of the instantaneous velocity time sequence of gas-liquid two-phase turbulent flow at different spatial locations in a reflux reactor by the constant-temperature hot-film anemometer.The paper describes development of a conditional sampling technique using instantaneous intensity factor and flatness factor of wavelet coefficients to discriminate the multi-scale coherent structures in gas-liquid two-phase turbulent flow and introduces the use of the method based on the phase-averaged waveforms of the structure of the single bubble to the study about gas-liquid two-phase turbulent flow in the bubble column.The results show that the bubble structure in the bubble column results in occurrence of singularity and intermittency in the gas-liquid two-phase turbulent flow.Only within the certain spray cone angle are some bubble structures found,and affected by the corresponding flat factor and intermittency.