Design of three-strand compact spinning system and numerical flow-field simulation for different structures of air-suction guides and suction inserts

This study aims to design a compact three-strand spinning approach as inspired by the twist and compact spinning. In the design process, auxiliary parts of twist and pneumatic compact spinning technologies were modified. First, a three-strand funnel and three-groove delivery cylinder were designed to feed three-strand into the drafting zone and control strand space. Then, air-suction guides and suction inserts with different structures of air-inlet slots were designed to create a separate condensing zone for each of the strands. Different structures of the air-suction guide and suction insert were used for modeling the compacting zone and four different systems were introduced. The effectiveness of compacting zones was discussed according to the numerical flow-field simulation studied with SolidWorks Flow Simulation software. Numerical simulation results showed that creating separate condensing zones for three-strand yarns was achieved with all of the new designs. However, the air-guide with longer air-inlet slot channels provided better flow-velocity components and static pressure values. It was also seen that using the same guide with narrowed slots suction insert results in greater flow-velocity components. In the experimental part, the guide with longer air-inlet slots and narrowed slots of suction insert was produced with a 3D printer and used for compact three-strand production. Properties of the compact three-strand yarns were compared with ring three-strand yarns to investigate compacting effects, and it was seen that better yarn properties were obtained with the compact three-strand spinning.

Flow Field Simulation and Efficiency Calculation of Muzzle Brake Based on ANSYS Fluent

The development of advanced artillery needs to be combined with simulation means, so, traditional calculation method and the flow field simulation method was employed to calculate the efficiency of a largecaliber muzzle brake we designed, and the results achieved by these two methods were 47.8% and 49.3%, respectively. Further, the overpressure value 1 m away from the muzzle was obtained through flow field simulation, and the far-field overpressure value was calculated using blast wave attenuation equations. The result suggests that the blast wave from the designed muzzle brake has little harmful impact. This paper provides an intuitive calculation method of muzzle brake efficiency, also, it provides theoretical support for research of high efficiency muzzle brake and personnel protection onboard.