Abstract
Knowledge of the structure of a flow is significant for the proper conduct of a number of industrial processes. In this case, a description of a two-phase flow regimes is possible by use of the time-series analysis in time, frequency and state-space domain. In this article the Discrete Wavelet Transform (DWT) is applied for analysis of signals obtained for water-air flow using gamma ray absorption. The presented method was illustrated by use data collected in experiments carried out on the laboratory hydraulic installation with a horizontal pipe, equipped with two Am-241 radioactive sources and scintillation probes with NaI(Tl) crystals. Signals obtained from detectors for slug, plug, bubble, and transitional plug – bubble flows were considered in this work. The recorded raw signals were analyzed and wavelet energy was extracted using multiresolution analysis. It was found that energies of wavelet approximation at 1-5 levels are useful to recognize the structure of the flow.
Highlights
Knowledge of a two-phase flow regime is significant for the proper conduct of a number of industrial processes
The data were collected in experiments carried out on a laboratory hydraulic installation with a horizontal plexiglas pipe
Measurement data were collected during b) experiments carried out on a laboratory hydraulic installation with a horizontal plexiglas pipe of 4.5 m length and the inner diameter of 30 mm
Summary
Knowledge of a two-phase flow regime is significant for the proper conduct of a number of industrial processes. Flow regime identification inspires many studies, Recent works describes a use for this purpose machine learning methods as e.g. artificial neural networks [112]. Computational intelligence methods utilize various features of signals in the time, frequency and state-space domain. Features of signals in the frequency domain may be determined using the Fourier Transform, Short-Time Fourier Transform, wavelet transform and other methods [11, 13, 14]. Wavelet transform is applied to signals obtained in two-phase liquid-gas flow measurements using gamma-ray absorption. Signals obtained for four structures of air-water flow as slug, plug, bubble, and transitional plug – bubble one were considered. The recorded raw signals were analyzed and energies of their wavelet decomposition were extracted using multiresolution analysis
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