Study On Void Fraction Measurement Method Of Slug Flow In Mini-pipe Gas-liquid Two-phase Flow Based On High-speed Photography

Gas-liquid two-phase flow exists widely in petroleum, chemical and other industrial production processes. During past few years, with the rapid development of small-scale industrial equipment, parameter measurement of mini-pipe two-phase flow becomes a popular field in current two-phase flow research. But the study on parameter detection methods of mini-pipe two phase flow is still at the initial stage, and is still not mature and lack of perfect theory basis and accurate mechanism model. So, researches on parameter measurement of mini-pipe two-phase flow are of important scientific significance and engineering application value.In this dissertation, based on high-speed photography, void fraction measurement methods of slug flow in mini-pipe two-phase flow are studied. Main works and innovations are listed as follows:1. A virtual binocular vision gas-liquid two-phase flow measurement system is designed and established based on high-speed photography. The system can simultaneously capture two mutually perpendicular angles’images of gas-liquid two-phase flow in mini-pipe.2. Base on image sequences, a void fraction measurement method for slug flow in horizontal mini-pipe gas-liquid two-phase flow is proposed, using support vector regression-particle swarm optimization (SVR-PSO). Firstly, the captured slug flow gray image sequences are converted into slug flow binary image sequences using digital image progressing technique. Then, effective time series are composed and values are extracted. Lastly, a void fraction regression model is established according to SVR-PSO. Experiments are carried out in a horizontal pipe with inner diameter of4.02mm and2.73mm respectively. The results show that the method is effective and feasible. The maximum relative errors of void fraction of slug flow are less than8%.3. Based on virtual binocular vision technique, a void fraction measurement model for slug flow in mini-pipe gas-liquid two-phase flow is established preliminarily, which can obtain the void fraction using two images captured from virtual binocular vision gas-liquid two-phase flow measurement system. A preliminary experimental verification is carried out in upward vertical pipe with inner diameter of2.73mm. Void fraction of slug flow is calculated. Experimental results show that the model is effective and feasible. The maximum relative errors of void fraction of slug flow are less than8%.