Multiresolution analysis of pressure fluctuation in horizontal swirling flow pneumatic conveying using wavelets

Wavelet multiresolution analysis and wavelet multiresolution cross-correlation analysis were applied to experimental pressure—time signals in order to analyze the characteristics of swirling flow pneumatic conveying in both Fourier and physical spaces. From random-like pressure fluctuations, the fluctuating pressure components due to dispersed suspension flow and dune flow can be extracted over a time-scale plane based on wavelet multiresolution analysis. It was found that the dominant scale of the heterogeneous suspension flow over the dunes increases along the flow direction and reaches 0.017 s in the fully developed region of the dune flow. Wavelet multiresolution cross-correlation analysis revealed that dunes with the same moving velocity of 1 m/s pass through test pipeline and no correlation existed at smaller scales that represent heterogeneous suspension flow over the dunes.