Optical measurement system for two-phase flow in horizontal small tube based on photodiode arrays

Based on photodiode array, an optical measurement system is established for gas-liquid two-phase flow in small tubes. A method is proposed for characterization and flow regime identification of gas-liquid two-phase flow. In the experiment, different flow regimes are observed in a horizontal glass tube with inner diameter of 4.02mm and outer diameter of 6.12mm, and voltage signals are obtained from the 8-element photodiode array through sensing circuits. Probability density function (PDF) and Fourier transform are used for the analysis on signal characteristics of flow regimes. To identify flow regimes, eigenvalues of the statistics are calculated, then the principal component analysis (PCA) is implemented to reduce the dimensionality of data sets, finally support vector machine (SVM) is applied for identification. Experimental results show that the optical system based on photodiode array is effective in the measurement of gas-liquid two-phase flow parameters in small tubes. The proposed method proves effective in characterization and flow regime identification of gas-liquid two-phase flow, and the experimental results are satisfactory.