2001 Volume 34 Issue 2 Pages 158-165
The recently developed technique of wavelet transform based on the localized wavelet functions has been applied for the analysis of nonlinear and nonstationary pressure fluctuation signals in a bubble column, because they are very complex and highly irregular as a consequence of the continual interactions among the bubble and liquid phases. The time series of pressure fluctuation signals have been expressed by means of discrete wavelet transform coefficients, multiresolution decomposition and scalogram. By this wavelet transform technique, the fluctuating pressure signals in a bubble column can be decomposed into its approximations and details at different resolutions. The energy of the details provides a measure of irregularity of the signal at various resolutions. Thus, this wavelet transform method enables us to obtain the frequency content of local complex flow behaviors in a bubble column, which are directly connected with the transport phenomena in it.