Light field bubble tracking velocimetry based on the global bubble position iteration and polar coordinate system similarity algorithm
The light field particle tracking velocimetry(PTV)can track the trajectories of the bubbles in the gas-liquid two-phase flow via a single camera.This method provide a solution for the measurement of bubble parameters in space-constraint applications.However,under the conditions of high bubble concentration and large bubble displacement,the matching accuracy of PTV bubbles in the light field is low,resulting in significant velocity measurement errors.In order to solve this problem,this paper proposed a bubble matching method based on global position iteration and polar coordinate system similar technology(GPPI-PCSS).The GPPI-PCSS method iteratively updated the positions of all bubbles in a single frame image through the three-dimensional displacement field obtained by the PCSS matching method.As a result,the bubble positions in the two frames gradually coincide and the accurate bubble matching results could be obtained.The performance of the GPPI-PCSS method was evaluated by experimental study of the bubble motion behavior in the bubbling bed through light field PTV.Results showed that the average bubble matching accuracy of the GPPI-PCSS method was 92.65%in the range of 0.5-7ms sampling interval and 0.15-0.35L/min air flow,which was higher than 81.38%of the traditional PCSS method and 84.12%of the relaxation method,respectively.In addition,the maximum motion velocity of bubbles measured by GPPI-PCSS method ranged from 38.34-49.87cm/s,which was consistent with the theoretical calculation value.These results indicate that the proposed GPPI-PCSS method could be used in light-field PTV technology to obtain accurate bubble velocity measurement results under the conditions of high bubble concentration and large bubble displacement.
light field imagingparticle tracking velocimetry(PTV)bubble matchingpolar coordinate system similar algorithmglobal location iteration