Abstract
Almost every modelling approach of bubbly flows includes assumptions concerning the bubble shape. Such assumptions are usually made based on single bubble experiments in quiescent flows, which is far away from the flow field observed in large-scale multiphase facilities. Considering low Morton-numbers and the highly deformable interface at medium and large Eötvös-numbers, the evaluation of the bubble shape in such systems under real flow conditions is highly desirable. In this study, we experimentally evaluate the bubble shape (in terms of aspect ratio), at low Morton-numbers, in different bubble column setups and a pipe flow setup under different operating conditions. The bubble shape in the bubble column experiments were obtained with cameras at Politecnico di Milano and Helmholtz-Zentrum Dresden Rossendorf (HZDR) whereas the shapes in the pipe flows were measured by the ultrafast electron beam X-ray tomography system (ROFEX) at HZDR. In the bubble column experiments almost the same shape is observed; conversely, the shape in the pipe flows distinctly depends on the flow conditions. In conclusion, in bubble columns the assumption of a constant shape regardless of the flow conditions is valid whereas in pipe flows the turbulence and shear rates can be strong enough to deform distinctly the bubbles.
Highlights
Related content- Theory of the stability of multielectron bubbles in liquid helium Wei Guo, Dafei Jin and Humphrey J Maris
Flows are observed in different industrial applications and in multi-phase reactors
The bubble shape in the bubble column experiments were obtained with cameras at Politecnico di Milano and Helmholtz-Zentrum Dresden Rossendorf (HZDR) whereas the shapes in the pipe flows were measured by the ultrafast electron beam X-ray tomography system (ROFEX) at HZDR
Summary
- Theory of the stability of multielectron bubbles in liquid helium Wei Guo, Dafei Jin and Humphrey J Maris. - Bubbly free and impinging jets under forced flow conditions: experimental study by means of PIV/PFBI Mikhail Yu Nichik, Konstantin S Pervunin and Dmitriy M. This content was downloaded from IP address 151.22.36.230 on 24/09/2018 at 09:38. 35th UIT Heat Transfer Conference (UIT2017) IOP Conf.
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