Numerical investigation into the effect of geometric shape of slot on air flow field in melt-blown for polymer fiber

In order to obtain smaller diameter melt-blown fiber, we improved the air slot of the melt-blown die in this research and designed the new melt-blown die with the gradually shrinking air slot and arc nose head. Using the numerical simulation method, we analyzed that the new die and the common die affect the velocity field, temperature field, air pressure field, and turbulence strength on the center line. The diameter distribution of the fiber obtained from the die was analyzed by using the one-dimensional tensile model of the melt-blown fiber. The results show that as compared to the common slot shape die, the new die improves the mean velocity along the center line in the fiber main stretch area by 56% and the peak velocity by 38.5%, increases the peak value of the air pressure in the air flow field, reduces the negative velocity in the return flow area, decreases the peak value of the turbulence intensity, and delays the air flow wave nearby the end face of the die, thereby make the fiber motion more smooth. At the same time, the new melt-blown die with the gradually shrinking air slot and arc nose head can make the fibers in the melt-blown process finer and lead to more lower energy consumption for producing the fibers of the same diameter.