Investigation of spherical and concentric mechanism of compound droplets

Abstract

Polymer shells with high sphericity and uniform wall thickness are always needed in the inertial confined fusion (ICF) experiments. Driven by the need to control the shape of water-in-oil (W1/O) compound droplets, the effects of the density matching level, the interfacial tension and the rotation speed of the continuing fluid field on the sphericity and wall thickness uniformity of the resulting polymer shells were investigated and the spherical and concentric mechanisms were also discussed. The centering of W1/O compound droplets, the location and movement of W1/O compound droplets in the external phase (W2) were significantly affected by the density matching level of the key stage and the rotation speed of the continuing fluid field. Therefore, by optimizing the density matching level and rotation speed, the batch yield of polystyrene (PS) shells with high sphericity and uniform wall thickness increased. Moreover, the sphericity also increased by raising the oil/water (O/W2) interfacial tension, which drove a droplet to be spherical. The experimental results show that the spherical driving force is from the interfacial tension affected by the two relative phases, while the concentric driving force, as a resultant force, is not only affected by the three phases, but also by the continuing fluid field. The understanding of spherical and concentric mechanism can provide some guidance for preparing polymer shells with high sphericity and uniform wall thickness.

Effects of surfactant adsorption on the formation of compound droplets in microfluidic devices

“…[5][6][7] There are stringent specications on the size of these shells since they contain deuterium and tritium fuels. [8][9][10] Therefore, it is important to precisely control their corresponding compound droplets, the precursor of polymer shells. 11,12 Compound droplets are successfully prepared by kinds of microuidic devices with different structures including cross-ow, co-ow and ow-focusing, but the formation mechanism is not clear enough, unfavorable to precise controllability of their structure and size.…”

Performance analysis of a K2CO3-based thermochemical energy storage system using a honeycomb structured heat exchanger

“…Therefore, numerical simulation tools to model the thermochemical reactions, understand the reaction kinetics, and optimize the system performance, are very essential. In the recent past, bionics based tools have been realized to be one of the advanced tools, especially in the field of fluid flow and heat transfer applications including chemical reactors [27], biomedical equipment [28,29], and electronic cooling [30][31][32][33][34]. The fin structures made by natural assortment encourage the improvement of the TCES device.…”

Simulation of the Gas Filling and Evacuation Processes in an Inertial Confinement Fusion (ICF) Hohlraum

“…In inertial confinement fusion (ICF), a capsule filled with deuterium-tritium is imploded to ignition and burns under appropriate conditions, which bring clean and sustainable energy [1][2][3][4][5]. In particular, the indirect drive approach of ICF relies on the efficient conversion of laser power to X-rays that heat and symmetrically drive the capsule implosion embedded in a cylindrical hohlraum [6,7]. The cylindrical hohlraum is initially filled through microcapillary fill tubes with low-Z gas to control the implosion symmetry [8,9].…”