An improved Lagrangian approach for simulating fiber whipping in slot-die melt blowing

Abstract

Melt blowing is a one-step approach for manufacturing microfibrous nonwovens. In slot-die melt blowing, a pair of air jets with high velocity and temperature is applied on the polymer and attenuates the polymer in to fibers. The fiber motion which was called vibration or whipping plays a crucial role in expressing the drag mechanism. In this study, an improved Lagrangian numerical approach was utilized to simulate the fiber whipping in melt blowing. The fiber whipping simulated in this study was significantly improved compared to other previous works. Meanwhile, the fiber diameter, fiber velocity and fiber temperature below the spinneret were simulated. The numerical simulation indicated that the most attenuation of fiber diameter occurred within 0.07 m below the spinneret; the fiber velocity increased gradually while the air velocity decreased rapidly along the spinning line, and the fiber velocity exceeded the air velocity where below a critical z-position; In addition, the fiber temperature decreased tardier than the decreasing of air temperature. This study illustrated that it was important to optimal design the air flow field which was supposed to fully utilize the air velocity and temperature together. In addition, the energy saving of melt blowing deserved to be taken into consideration.