A Parameter Measurement Svstem For Gas-liquid Two-phase Flow In Small Tubes Based On Photodiode Arrays

Small-tube two-phase flow systems are increasingly seen in production process of petro-chemical industries, metallurgy, energy and other industrial sectors, and the parameters of two-phase flow are of great importance to operational procedures, process reliability as well as quality and cost control. Researches on small-tube two-phase flow systems are of great scientific value and application potential, in-depth theoretical analysis and parameter measurement are still required in related fields.In this thesis, a measurement system based on photodiode array is designed for the parameter measurement of small-tube gas-liquid two-phase flow, realizing the identification of flow regime and slug flow average volume fraction measurement of small tube two phase flow. Main works and innovations of this thesis are listed as follows:1. A small tube gas-liquid two phase flow parameter measurement system based on photodiode array is designed and established as described in this thesis, which is capable of acquiring signals of flow characteristics of gas-liquid two phase flow in small tubes with inner diameter of1.94mm,2.73mm and4.02mm.2. Flow characteristics are analyzed with the system established, and typical flow regimes of annular flow, stratified flow, bubbly flow and slug flow are observed and identified in the experiment. Signal characteristics are analyzed with Fourier Transform and Probability Density Function. Flow regime classifiers are designed based on Support Vector Machine, and eigenvalues extracted for regime identification. Experimental results show that the method proposed is effective and the identification accuracy for typical flow regimes is above90%.3. A void fraction measurement technique for slug flow is proposed based on photodiode array signal analysis. By analyzing the characteristics of small tube gas-liquid two phase flow, combined with the use of Support Vector Regression, a model of slug flow is established. Experimental results in small tubes with inner diameter of2.73mm and4.02mm show that the method used is effective and the maximum relative error is below10%.