Compact-siro spun with lattice apron combines compact spinning and siro spinning, and is widely put into practice. In this paper, compact-siro spun models with the parallel shaped slots, oblique parallel shaped slots and V-shaped slots were simulated. Based on the airflow data in the condensing zone, the geometrical model of single fiber is built, and then the trajectory of single fiber can be got. The morphological changes and movement process of fiber strands in the flow field of condensing zone were verified by the comparison experiments of yarn morphology, hairiness, tensile and evenness properties. The results showed that the V-shaped slot achieved the optimal agglomeration effect and yarn performance. The theory analysis gives foundation and explanation for the experiment, and also provides a theoretical basis for optimizing the properties of compact-siro yarn in production practice.
During the air flow twisting process of jet vortex spinning, the moving characteristics of flexible free-end fiber are complex. In this paper, the finite element model of the fiber is established based on elastic thin rod element. According to the air pressure and velocity distribution in the airflow twisting chamber of jet vortex spinning, this paper analyzes the undetermined coefficients of the finite element kinetic differential equation of the free-end fiber following the principle of mechanical equilibrium, energy conservation, mass conservation and momentum conservation. Based on numerical simulation, this paper gets the trajectory of the free-end fiber. Finally, the theoretical result of the free-end fiber trajectory by finite element simulating is tested by an experimental method. This paper has proposed a new method to study the movement of the fiber and learn about the process and principle of jet vortex spinning.
The flooding process is one of the main concerns of damaged ship stability. This paper combines the volume of fluid (VOF) method incorporated in the Navier-Stokes (NS) solver with dynamic mesh techniques to simulate the flooding of a damaged ship. The VOF method is used to capture the fluid interface, while the dynamic mesh techniques are applied to update the mesh as a result of transient ship motions. The time-domain flooding processes of a damaged barge and a rectangular cabin model are carried out based on the abovementioned method, and the computational results appear compatible with the experimental data. During the flooding process, the motion of the flooding flow at different stages is observed and compared with that observed in real conditions. The time-domain research of the flooding process is the starting point for subsequent establishment of damaged ship’s roll movement and capsizing the mechanism of dead ship condition in wave.