A Particle Image Velocimetry (PIV) method based on the image separation andreconstruction with the median filter and triangular Bezier patch was proposed to measure multiplevelocity fields from single-camera images in...A Particle Image Velocimetry (PIV) method based on the image separation andreconstruction with the median filter and triangular Bezier patch was proposed to measure multiplevelocity fields from single-camera images in the present study. The method was examined on syntheticPIV images with the Green-Taylor two-phase vortex flows and the test results showed high accuracyand highly correct tracking percent compared with the exact solution. An experiment of the bubblyjet flow was also conducted as a practical demonstration of the present method. As a result, it isconfirmed from the simulation image examination and the experimental measurement that the proposedmethod shows a good performance in the measurement of bubble and particle phases.展开更多
Bubble-bubble interaction in free rising bubbly flows is experimentally investigated in the present study. The velocity vectors of the bubbles are measured by a stereoscopic bubble-tracking technique and then the rela...Bubble-bubble interaction in free rising bubbly flows is experimentally investigated in the present study. The velocity vectors of the bubbles are measured by a stereoscopic bubble-tracking technique and then the relative velocity vectors of two nearest-neighbor bubbles are calculated with high statistical reliability. With the measurement data at Reynolds number ranging from 5 to 75, the vertical attraction and the horizontal repulsion are confirmed for Re<10 as known by the past study based on Navier-Stokes simulation. The new finding of the present measurement is that the bubbles of Re>30 have repulsive velocity bothin the horizontal and the vertical directions as those rise closely. Moreover, the three-dimensional structure of the bubble-bubble interaction is discussed with the data analysis of the interaction vector fields.展开更多
文摘A Particle Image Velocimetry (PIV) method based on the image separation andreconstruction with the median filter and triangular Bezier patch was proposed to measure multiplevelocity fields from single-camera images in the present study. The method was examined on syntheticPIV images with the Green-Taylor two-phase vortex flows and the test results showed high accuracyand highly correct tracking percent compared with the exact solution. An experiment of the bubblyjet flow was also conducted as a practical demonstration of the present method. As a result, it isconfirmed from the simulation image examination and the experimental measurement that the proposedmethod shows a good performance in the measurement of bubble and particle phases.
基金This work was supported as Grant In Aid Research by the Japanese Ministry ofEducation Science and Culture (GrantNos: CN15560135 and CN15760104)
文摘Bubble-bubble interaction in free rising bubbly flows is experimentally investigated in the present study. The velocity vectors of the bubbles are measured by a stereoscopic bubble-tracking technique and then the relative velocity vectors of two nearest-neighbor bubbles are calculated with high statistical reliability. With the measurement data at Reynolds number ranging from 5 to 75, the vertical attraction and the horizontal repulsion are confirmed for Re<10 as known by the past study based on Navier-Stokes simulation. The new finding of the present measurement is that the bubbles of Re>30 have repulsive velocity bothin the horizontal and the vertical directions as those rise closely. Moreover, the three-dimensional structure of the bubble-bubble interaction is discussed with the data analysis of the interaction vector fields.
