单孔排气气泡特征识别与参数提取方法OA北大核心CSTPCD

Gas-liquid two-phase flow is prevalent in various industries.The measurement and statistical analysis of bubbles characteristics are useful for the investigation of the bubbles motion and generation.Therefore,it can provide the fundamental data for physical mechanism and process control research.In this paper,bubble images were captured by a high-speed camera system at different liquid flow rates and aeration volumes in the circulating water tank.Given that bubble coalescence and breakup during motion could lead to overlapping and sticking issues in the images,these phenomena would cause significant measurement errors in bubble characterization parameters.To address these issues,this paper improved the marker extraction method of the watershed algorithm.The method obtained foreground markers by utilizing the extreme points of the distance transformed image for suppression and fusion,thereby improving the accuracy of the bubbles segmentation.Least squares ellipse fitting was conducted on the segmented bubbles to reconstruct the bubbles profile and obtain their parameters.Experimental results showed that the proposed method have obvious improvement on segmenting the adherent bubbles and extracting the bubble features.Compared to the methods of erosion operation and threshold segmentation for extracting markers,the proposed method increased the accuracy by 22.7%and 13.6%,respectively.Moreover,statistical analysis of the obtained data showed that the number of bubbles increases slightly with increased ventilation volume,while the average bubble size increased significantly.It was found that the ventilation volume mainly affects the size of the bubbles.On the other hand,the bubbles motion was affected by the liquid flow rate.It was noted that the increased liquid flow rate would generate more bubbles with small size due to bubbles breakup.