The Theory Of Fractional Calculus And Its Application In Two Phase Flow

Gas liquid two phase flow widely exists in all kinds of scientific application research field and industrial production process. The flow patterns and their dynamic characteristics of two phase flow seriously affect the heat and mass transfer rate,momentum loss and pressure gradient of the two phase flow. In general, the flow pattern is determined by the characteristics of the differential pressure fluctuation signal, but the acquisition of pressure fluctuation signal can be influenced by many factors, such as pipe vibration. Therefore, the collected signal is filtered and processed in the study of two phase flow regime.The theory of fractional wavelet transform which based on fractional fourier transform is used to make denoising analysis on the signal of gas-liquid two-phase flow.The multi-resolution analysis theory of traditional wavelet transform is generalized to the fractional fourier domain by FRWT. By using the flexibility of the fractional order, the denoising for the signal of gas liquid two phase flow is realized more effectively.In the aspect of flow pattern recognition, making a fusion of Hilbert-huang transform theory and fractional Hilbert transform method, the IMF component is obtained at different scales by using the EMD decomposition method in HHT theory to process the signal.Then making multi order FHT analysis on the IMF component of different flow patterns, in order to complete flow pattern recognition of gas liquid two phase flow.Dynamic characteristics of different flow regimes of gas liquid two phase flow are studied by the method of combining fractional order relative entropy and symbolic dynamics. Entropy has been widely used in the research of two phase flow, but the fractional order entropy is almost not involved in the flow pattern analysis. The traditional relative entropy is not ideal to reflect the dynamic behavior of flow regime.This paper studies on fractional flow symbolic relative entropy and its evolution mechanism by the change law of symbolic relative entropy of multiple orders, provides a new idea for further understanding of the dynamic characteristics of flow pattern.