【作者】 钟兴福；

【导师】 李海青；

【作者基本信息】 浙江大学 ， 控制科学与工程， 2001， 博士

【摘要】 两相流参数的测量一直是倍受关注的问题。两相流流型辨识，流量和含率的测量对两相流系统的工业应用具有重要的意义。本文在对国内外有关文献资料研究的基础上，提出了将混沌、分形技术应用于两相流参数检测的新思想。主要工作及成果如下： 1 回顾了混沌理论的发展历史，在对混沌动力学方法作了比较全面 的综述之后，提出了基于混沌的两相流参数测量思路，着重研究 了混沌方法是如何应用于两相流参数检测的问题，设计出基于混 沌方法的两相流参数检测方案，为两相流参数测量开辟了一条新 的途径。 2 对大直径圆管中油水两相垂直流动时的流型重新进行了实验描 述和划分，建立了具有实用价值的流型判别标准，实现了用流量 法和持水率法对流型的辨识。通过模拟实验发现垂直管的流型具 有尺度效应，实验证明，不同实验条件下，尤其是在不同管径下 用流量或流速表示的过渡判据不能成比例地放大或缩小到其它 管径中进行流型判别。 3 建立了适用于垂直管两相流系统的两相流动非线性动力学模 型，用数值实验证明了两相流动中存在混沌现象。理论计算出两 相流系统由稳定的流动转变为混沌时的分叉值和两相流动发生 混沌现象时基本参数的范围。制作出具有推广意义的两相流动系 统的理论图版，并在油水两相流动实验中得到了验证。建立的非 线性动力学模型提供了一种研究两相流动特性的新理论工具。 4 提出了基于混沌分析方法的两相流流型辨识方法，实现了用 Poincare截面、分维数等对流型的客观辨识。通过大直径圆管中 的大量实验验证，对油泡流、分散油泡流两种流型的总体辨识成 功率都在78％以上。实验结果同时表明，关联维数对流型变化比 较敏感，可以作为判别流型的指示器。 5 提出了基于Poincare截面、关联维数分析，实现从单变量动态测 量信号中提取流量和含率信息的两相流参数检测的新方法，并通一 过实验验证了这种方法的可行性。更多还原

【Abstract】 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.更多还原