Research On Three-dimensional Measurement And Behavior Of Bubble In Gas-liquid Two-phase Flow

With the development of science technology, gas-liquid two-phase flow has beenwidely applied in many fields such as petroleum engineering, environmentalprotection, and nuclear reaction. The effect of gas-liquid two-phase flow on theengineering application depends largely on the bubble motion modality and theinteraction between the discrete phase and the continuous phase. Therefore, in orderto investigate the flow characteristic of gas-liquid two-phase further, gain theknowledge of the movement mechanism of gas-liquid two-phase flow and theinteraction between bubbles, and guide the manufacture as well as practicalapplications. The research on three dimensional measurement and bubble behavior ingas-liquid two-phase flow is of great importance.In this paper, virtual binocular stereo vision measuring system is built on thebasic of studying the theory of binocular stereo vision. The calibration technique ofthe three-dimensional measurement and an overlapping bubbles partition method ingas-liquid two-phase flow are discussed deeply. The three-dimensional featureparameters are obtained by matching technique. Besides, the bubble behavior in theflow field is analyzed preliminarily. The details are as follows:The principle of virtual stereo vision measurement system and mathematicalmodel are studied deeply, the calibration method of the system is further deliberated.The accuracy of the three-dimensional reconstruction is optimal when the calibrationreference substance is placed in the water tank, the left virtual camera, right virtualcamera and sensor are calibrated. The absolute error of the space distancemeasurement is excels0.13mm and the relative error is excels0.49%.As to the overlapping bubbles in the three-dimensional measurement of bubble,the specific properties of overlapping bubbles images which are captured by the threedimensional measurement system are taken into account, an overlapping bubblespartition method is developed based on chain code difference, combining concavityarc length with middle axial constraint. Absolute chain code difference is used todetect the candidate separation points, combining concavity arc length with middleaxial constraint, the overlapping bubbles are recognized eventually.The research status of bubble volume and gas volume fraction in gas-liquid two-phase flow is analyzed deeply. According to the specific structure information ofvirtual stereo vision measurement system, the spatial position relationship of twovirtual image planes is obtained. The least square error ellipse fitting method isutilized to match the edges of bubbles in two virtual image planes, and theinformation of the bubble in the two two-dimensional image planes is obtained, thethree-dimensional reconstruction of bubble is achieved.The three-dimensional feature parameters of bubble are acquired by virtualbinocular stereo vision measurements system, and the factors which affect the bubblebehavior are analyzed preliminarily. The flow mechanism of gas-liquid two-phaseflow will be discussed at the basic of the analysis of the interaction between bubbles.