【摘要】 从理想的单气泡运动物理模型和离散正交小波与统计相结合的信号处理技术研究了泡状流压力波动的机理与多尺度时频规律,得到以下结论:泡状流的压力波动主要来源于气泡的运动和诱导湍流及液相湍流,其中在低流速下前者产生的压力波动幅度大于后两者;存在一个临界频率,低于该频率压力信号均方根随频率的增加而增加,高于该频率压力信号均方根随频率的增加而减小;发生流型转变时压力信号的时频特征发生明显改变,最大均方根出现在更低的频率区。更多还原

【Abstract】 The mechanism of pressure fluctuation in bubbly flow was investigated on basis of thephysical model of ideal single moving bubble. And the multi-scale time-frequency characteristics ofthe fluctuation were analyzed with both the discrete wavelet and the statistics theory. The resultswere induced as followed. The pressure fluctuation in bubbly flow is resulted from the moving bubble,the derivational turbulence by bubble, and the liquid turbulence. The fluctuation amplitude resultedfrom moving bubble can be greater than that resulted from other two reasons under the condition oflow liquid velocity. The distribution of RMS pressure has a distinguished difference across a criticalfrequency, where the RMS pressure increases with frequency in the frequency region lower than thecritical frequency while decreases in the region greater than the critical one. The time-frequencycharacteristic of pressure signal has a distinct change at the flow pattern transition, which the maximumRMS pressure will transfer to a lower frequency.更多还原