{"title":"Investigation of the critical flow velocity for detachment between various hydrophobic glass beads and bubbles in turbulent flow field","authors":"Mianyan Yang, Zhijun Zhang","doi":"10.1016/j.powtec.2025.120745","DOIUrl":null,"url":null,"abstract":"<div><div>The critical flow velocity required to detach glass beads (soda-lime) of different hydrophobicity from bubbles was investigated. Using a home-made turbulence controlling system to observe the centrifugal motion of glass beads. The results indicated that different flow velocities were achieved by controlling the rotational speed. Different flow velocity indirectly affected the centrifugal acceleration when the centrifugal detachment of glass beads occurred. When the flow velocity exceeded the critical value, the different hydrophobic glass beads and bubble aggregates experienced centrifugal detachment force also reached the critical value. Due to the pinning effect, the more hydrophobic the glass beads attached to the bubbles, the more stable the aggregates formed. It was necessary to increase the flow velocity to enhance the centrifugal detachment force. The three-phase contact line (TPCL) between glass beads and bubbles rapidly slipped and contracted when attachment force was less than detachment force in centrifugal motion. Resulting in a noticeable necking phenomenon that completed the detachment. Meanwhile, the detachment behavior between glass beads and bubbles did not occur at specific locations, but rather randomly. It was depended on the size and strength of the vortex at that location, as well as the stability of attachment between bubbles and various glass beads.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"455 ","pages":"Article 120745"},"PeriodicalIF":4.5000,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Powder Technology","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0032591025001408","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, CHEMICAL","Score":null,"Total":0}
引用次数: 0
Abstract
The critical flow velocity required to detach glass beads (soda-lime) of different hydrophobicity from bubbles was investigated. Using a home-made turbulence controlling system to observe the centrifugal motion of glass beads. The results indicated that different flow velocities were achieved by controlling the rotational speed. Different flow velocity indirectly affected the centrifugal acceleration when the centrifugal detachment of glass beads occurred. When the flow velocity exceeded the critical value, the different hydrophobic glass beads and bubble aggregates experienced centrifugal detachment force also reached the critical value. Due to the pinning effect, the more hydrophobic the glass beads attached to the bubbles, the more stable the aggregates formed. It was necessary to increase the flow velocity to enhance the centrifugal detachment force. The three-phase contact line (TPCL) between glass beads and bubbles rapidly slipped and contracted when attachment force was less than detachment force in centrifugal motion. Resulting in a noticeable necking phenomenon that completed the detachment. Meanwhile, the detachment behavior between glass beads and bubbles did not occur at specific locations, but rather randomly. It was depended on the size and strength of the vortex at that location, as well as the stability of attachment between bubbles and various glass beads.
期刊介绍:
Powder Technology is an International Journal on the Science and Technology of Wet and Dry Particulate Systems. Powder Technology publishes papers on all aspects of the formation of particles and their characterisation and on the study of systems containing particulate solids. No limitation is imposed on the size of the particles, which may range from nanometre scale, as in pigments or aerosols, to that of mined or quarried materials. The following list of topics is not intended to be comprehensive, but rather to indicate typical subjects which fall within the scope of the journal's interests:
Formation and synthesis of particles by precipitation and other methods.
Modification of particles by agglomeration, coating, comminution and attrition.
Characterisation of the size, shape, surface area, pore structure and strength of particles and agglomerates (including the origins and effects of inter particle forces).
Packing, failure, flow and permeability of assemblies of particles.
Particle-particle interactions and suspension rheology.
Handling and processing operations such as slurry flow, fluidization, pneumatic conveying.
Interactions between particles and their environment, including delivery of particulate products to the body.
Applications of particle technology in production of pharmaceuticals, chemicals, foods, pigments, structural, and functional materials and in environmental and energy related matters.
For materials-oriented contributions we are looking for articles revealing the effect of particle/powder characteristics (size, morphology and composition, in that order) on material performance or functionality and, ideally, comparison to any industrial standard.