A novel fuzzy-logic based method for determination of individual bubble velocity and size from dual-plane ultrafast X-ray tomography data of two-phase flow. (November 2017)

• Record Type: Journal Article
• Authors: Banowski, Manuel; Patmonoaji, Anindityo; Lucas, Dirk; Hampel, Uwe
• Is Part Of: International journal of multiphase flow. Volume 96(2017)
• Page Start: 144
• Page End: 160
• Publication Date: 2017-11
• Subjects: Ultrafast X-ray tomography -- Image processing -- Bubbly flow -- Bubble velocity, Bubble size; Multiphase flow -- Periodicals; Écoulement polyphasique -- Périodiques; Multiphase flow; Periodicals; 620.1064
• DOI: 10.1016/j.ijmultiphaseflow.2017.07.012
• Languages: English
• ISSNs: 0301-9322

Abstract

Highlights: A novel fuzzy-logic based algorithm for estimating bubble velocities is presented. The new algorithm tries to identify twin-bubbles basing on volume, lateral displacement and temporal displacement in both scanning planes of dual-plane ultrafast X-ray tomography data. The algorithm is applicable for bubble flows as well as slug flows. The results are individual three-dimensional bubble velocities. The results give well insights on effects of bubble forces. Abstract: Ultrafast X-ray tomography enables non-invasive imaging of gas-liquid flows with high spatial and temporal resolution. While it is relatively straightforward to extract e.g. gas fraction profiles from cross-sectional tomographic images, the extraction of bubble and gas-liquid interface information requires advanced image processing techniques. Thereby it is an important necessity to transform the temporal scale in the scanned sequences into a corresponding length scale for obtaining correct volumetric information. For bubbly flows this means that the velocity of the dispersed phase, e.g. the gas bubbles, has to be determined from dual-plane scans. A common and widely applied method to obtain gas phase velocities is cross-correlating the image sequences of the two scanning planes. This gives an averaged velocity for each position in the cross-section. In the present work, a new method is introduced, which determines the velocity of individual gas bubbles. This new method is termed as "bubble twinning method", because it tries to identify twin-bubbles in both scanning planes. The developed algorithm compares essential bubble parameters, that is, volume, position and residence time in the slice, by applying a fuzzy-logic based membership function approach. The algorithm was tested for bubbly flow as well as slug flow conditions. Results are compared with established theoretical predictions as well as the cross-correlation method.