Image Measurement And Analysis Of Bubble Motion Characteristic In Flow Field Of Spillway Bucket

Gas-liquid two phase flow is the most complicated two phase flow,for it has transformable interface and compressible air phase.There are lots of research works which have developed earliest.However,limited by experimental means and its difficulty,the development had been slow then.Recently,image measuring technique has become a hot research topic in the field of measurement for its advantages such as high mass resolving power, high sensitivity,rapid and non-contact gauging.With the application to the spillway tunnel of the Yalongjiang hydroelectric project which has high water head,several problems of the aerated water flows are investigated.Image measurement of high speed two-phase flow field was realized.The main contents of the studies and achievements are as followed:(1)According to the Jinping First Stage spillway tunnel shape design of Yalong river hydropower development,the physical model of tunnel bucket of scale of 1:100 was designed and manufactured;(2)According to Machine Tool Design Code,the camera guide rail which was needed by image measurement was designed and manufactured.The camera stand was mainly composed of leading track unit of rolling motion in line-movement,horizontal lead screw,vertical leading track unit of rolling motion in line-movement and vertical lead screw,and it can control accurate position of the camera.The precision of measurement reaches to 1mm.(3)LED array for surface light source which was used for lighting was designed and manufactured and suitable power equipment was matched.(4)Micro-bubble generator was designed and manufactured,it can generate bubbles,and the diameters of bubbles were 0.1-0.9mm;(5)After reading AVI video file format by MATLAB,using digital image processing method to process the image of two-phase flow and extracting the bubble,then the number of bubbles,bubble size and shape center coordinate in local flow field were computed and obtained.The PTV algorithm was applied and got some parameters such as velocity and moving trace.(6)Through the calculation,the discrete size distribution of bubble,law of changes of the velocity along cross-section,changing law of velocity components along the way,porosity and movement trace and range of bubble was gained.;...