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.
Three-dimensional (3D) ceramic fiber assemblies have good application prospects for thermal protection. Solution Blow Spinning (SBS) is a simple way to produce 3D fiber assemblies by using air turbulence to construct and stack fluffy fiber layers simultaneously. However, existing research lacks the study of evolutionary laws and exploration of the related mechanisms of transforming 2D fiber assemblies into 3D. In this study, we propose a self-supportive assembly strategy that can controllably produce 3D fiber macrostructures under the impact of high-speed airflow. We revealed the assembly mechanism of 3D fiber assemblies in air turbulent flow fields using in-situ observation with a high-speed camera and finite element analysis. Finally, ceramic fiber aerogels with lamellar structure, ultra-low density (9.5 mg cm −1 ) and extremely low thermal conductivity (0.0254 W m −1 K −1 ) were obtained by calcination. The lamellar structure gives them the ability to show high compressibility up to 90 % strain and high compression fatigue resistance of 1000 cycles at 50 % strain. In addition, the aerogels have the same tensile fracture strain (23.5 %) at 1300°C as at room temperature. This work is of great significance for the development, large-scale production, and application of high-performance 3D fiber aerogels.
危险品化学品经营许可证（带存储）