Applications Of Chaos Dynamics To Two-Phase Flow Measurement

Two-phase flow parameter measurement is an unresolved problem. The identification of two-phase flow patterns, flowrate and phase fl-action measurement are very important for the industrial applications of two-phase flow system. This dissertation applies chaos and fractal technique to the two- phase flow measurement. The main research results and contributions are listed as following: 1 Based on the review of chaos techniques and its applications, a new idea and a new scheme for flow parameter measurements of two-phase flow are proposed. 2 Flow patterns are classified by experimental investigation of oil and water mixture flow in large diameter vertical pipes. Practical criterion of flow pattern identification is developed. The flow pattern can be identified by the measurements of flow rate and water holdup. The experimental results also show that the proposed flow pattern identification criterion can not be applied to other pipes with different diameter because of the scale effect of flow pattern in large diameter vertical pipes. 3 A nonlinear dynamical model of two-phase flow is developed. The nonlinear dynamical behavior (chaos phenomena) of two-phase flow systems is proved by numerical experiments. Based on this model, some bifurcation parameters are obtained, as well as the flow-parameter ranges of two-phase flow when the chaos phenomena take place in two-phase flow systems. Also, a theoretical graph is developed and verified by oil/water two-phase flow experiments. The presented model provides a new theoretical tool for the study of two-phase flow. 4 A new method for flow pattern identification is presented based on the chaos techniques by using Poincare map and fractal dimension etc.. The experimental results show that the total accuracy to distinguish bubble flow and dispersed bubble flow is above 78% and the correlation dimension can be used as flow pattern indicator because of its sensibility to the change of flow pattern. 5 A new method for the on-line measurements of flow rate and water iii fraction from a time series is proposed by using Poincare map and correlation dimension analysis. The feasibility of this method is supported by experiments.