Study On Parameter Measurement Method For Mini-pipe Gas-liquid Two-phase Flow Based On High-speed Camera System

In recent years, due to the rapid development of small scale two-phase flow systems that appear in chemical reactors, exchangers, cooling processes and many other systems, more and more researchers are devoting to the study on the characteristics, mechanism and other aspects of small scale two-phase flow systems. However, parameter measurement method for mini-pipe gas-liquid two-phase flow is still limited. High-speed photography is an effective method for mini-pipe gas-liquid two-phase flow parameter measurement. Therefore, in this thesis, flow regime identification and voidage measurement in mini-pipes are studied based on high-speed photography. Main works and innovations are listed as follows:1. A mini-pipe gas-liquid two-phase flow parameter measurement system is designed based on high-speed photography. The system mainly composes three parts: fluid control subsystem, high-speed image capture subsystem and voidage calibration subsystem. Gas-liquid two-phase flow experiments are carried out in the pipes with inner diameter of 4.0mm,2.8mm and 1.8mm.2. A method for the identification of gas-liquid two-phase flow regime in mini-pipes is presented based on textural feature series. Image textural feature series are extracted instead of textures of one single static image. Then the standard deviation and the mean value of the textural feature series are computed as the inputs of support vector machine to identify the gas-liquid two-phase flow regime. The identification accuracies of five typical flow regimes are all above 95%. Experimental results indicate that the method presented can significantly improve the identification accuracies compared with the method based on one single static image in mini-pipes.3. Voidage measurement models for different flow regimes in mini-pipes are established based on high-speed photography. A preliminary experimental verification was carried out in a horizontal pipe with inner diameter of 2.8mm. The measurement relative errors of the five typical flow regimes are all below 10%. Experimental results indicate that the models established are feasible for gas-liquid two-phase flow voidage measurement in mini-pipes.