Experimental and computational analysis of the aerodynamics of melt blowing dies

An experimental and computational study of melt blowing jets and processes was done. Computational studies were done on three types of melt blowing jets: conventional annular, tapered annular and swirling. Conventional annular melt blowing jets were simulated and compared with experimental data. Tapered annular jets were simulated and compared with conventional annular and slot jets. Swirling adhesive nozzles were simulated and compared with experimental data. Experimental work consisted of measurements of both slot dies and swirling adhesive nozzles. Pitot tube measurements were made on the air flow in the jets of both slot dies and swirling adhesive nozzles. The temperature field of a heated slot die jet was also measured. Online diameter measurements were made of the fibers produced by a pilot-scale melt blowing die using a new Ensemble Laser Diffraction (ELD) technique. Light absorbance of fiber mats produced by a slot die was measured. The vibration amplitude of fibers during the melt blowing process was measured photographically. It was found that the jets studied act largely as variations of classical circular and rectangular jets. For all the jets studied, it was found that the far field decay coefficient was higher for melt blowing jets than for the classical jet geometries. Accurate computational techniques were developed for both annular and swirl nozzle geometries.