Abstract:

In order to study the effect of swirl nozzle spinning method on yarns of different linear density, vortex nozzle internal airflow characteristics, air pressure and velocity distribution of yarns with different linear densites under the effect of vortex were simulated by means of computational fluid sojtware, and spinning experiment was designed to validate the simulation result. The results show airflows move clockwise toward the yarn channel inlet and outlet direction, respectively, after yarns enter into the yarn channel, and the yarn surface hairiness number are mainly decreased by air wrapped force and the relative revolving action because of the self-twisting of the yarn. The pressure near the pipe wall is higher than yarn channel axis pressure because of the airflow rotating feature, therefore pressure distribution on the surface of yarns of different linear densites yarns and wrapped force are different. Yarn linear density is smaller, the pressure distribution of yarn surface is more intensive, and velocity along x, y and z axis have relatively large fluctuations. The pressure and velocity distribution on the surface of 20 tex yarn are better than that of 10 tex, 30 tex and 40 tex yarns. The experimental results show that the hairiness reduction ratio of 20 tex yarn made from 40 % of hemp and 60% of cotton reaches 87.6% under 0.2 MPa pressure, which is consistent with the results of numerical simulation.

Key words: swirl nozzle, vortex spinning, hairiness, liner density