Fluid analysis of gas-liquid two-phase flow based on semiconductor laser measurement and s transform

In this paper, we collect the flowing signal of the gas/liquid two-phase flow using the semiconductor laser measurement technique. S transform is then used to analyze the collected signal on both time and frequency domains. S transform is introduced and a method to indicate the flow pattern change based on the S transform power spectrum is also proposed. We apply S transform on 5 flow patterns of laser measurement signal under over 100 circumstances. The results show that S transform power spectrum is closely related to flow patterns. Peak value will appear in the case of bubble flows with apparent randomness in the distribution on the time axis. Peaks appear between 10 and 100Hz. Slug flow has the lowest peak value of the power spectrum and shows obvious periodicity. The power is focused at about the 50Hz of the mid frequency band. When the flow is evolved into churn flow, the peak of the power spectrum for S transform increases again, but the maximum value is slightly lower than that of the bubble flow and with periodicity on the time axis and wider frequency bandwidth.