Characterization of pressure signals in a bubble column by wavelet transform

The recently developed technique of wavelet transform based on the localize d wavelet functions has been applied for the analysis of nonlinear and nons tationary pressure fluctuation signals in a bubble column, because they are very complex and highly irregular as a consequence of the continual intera ctions among the hubble and liquid phases. The time series of pressure fluc tuation signals have been expressed by means of discrete wavelet transform coefficients, multiresolution decomposition and scalogram, Ey this wavelet transform technique, the fluctuating pressure signals in a bubble column ca n be decomposed into its approximations and details at different resolution s, The energy of the details provides a measure of irregularity of the sign al at various resolutions. Thus, this wavelet transform method enables us t o obtain the frequency content of local complex flow behaviors in a bubble column, which are directly connected with the transport phenomena in it.