非牛顿流体中气液两相流流场结构的小波分析

为了揭示流体流动中的隐含结构及湍流运动规律，利用三维激光多普勒测速仪对非牛顿流体中气泡上升过程液相速度场进行了测量，并借助小波方法对瞬时速度时间序列进行分析．局部间歇测度（LIM）峰分布的相似性说明湍流中存在大旋涡和小旋涡的串级结构，而LIM峰分布的不完全一致性说明湍流中存在相干结构．对不同小波尺度下能量分布的比较发现，在中尺度区，由于气泡的连续通过，该尺度范围内的能量占据了总能量的绝大部分，说明气泡的通过对液相的能量传递有很大贡献．另外，黏度增大使得小涡占据的能量减小，由小涡传递和耗散的能量减少，因此含能尺度的能量分布变宽．

Wavelet Analysis of Gas-Liquid Two-Phase Flow Field Structure in Non-Newtonian Fluid

In order to detect the hidden structures and the pattern of turbulence in fluid flow,the liquid velocity field was measured with 3D laser Doppler velocimeter （LDV） during the single bubble seriate rising process in non-Newtonian fluid, and wavelet method was adopted to analyze the time series of instantaneous velocity. The comparability of local intermit- tency measure （LIM） distribution displayed the existence of the cascade structure of big eddy and small eddy,and the incon- sistency of LIM distribution showed the existence of coherent structure. Comparison of the power distribution at various wavelet levels indicated that power at the middle level occupied most part of the total power due to bubble seriate pass,and the pass of bubble made great contribution to the power transfer of liquid. In addition, the increase of viscosity of the solution brought about decrease of the power occupied by small eddy ,and the power of transfer and dissipation through small eddy decreased, therefore the power distribution of energy range was widened.