Identification of two-phase flow patterns in minichannel based on RQA and PCA analysis

In the paper it has been shown that the analysis of dynamics of void fraction changes in time can be used for identification of two-phase flow patterns. The two-phase flow (air-water) in horizontal square minichannel (3 × 3 mm) has been analysed. The laser-phototransistor sensor signal was used for qualitative assessment of void fraction in minichannel. For data analysis there has been used the recurrence quantification analysis and the principal component analysis. The method of selection of coefficients resulted of recurrence quantification analysis has been proposed. Those coefficients describe the different aspects of two-phase flow patterns, but they are not independent variables describing the dynamics of two-phase flow. To obtain the set of independent variables characterising the dynamics of two-phase flow patterns the principal component method has been used. The proposed method allows us for the identification of following two-phase flow patterns: flow of micro-bubbles, flow of micro- and mini-bubbles, flow of micro- and mini-bubbles with confined bubbles, slug flow, stratified flow. The obtained results confirm that this type of analysis can be considered as an alternative way of identification of two-phase flow patterns in the minichannel.