Effects of Die Geometry on the Flow Field of the Melt-Blowing Process

Krutka, Holly; Shambaugh, and Robert L.; Papavassiliou, Dimitrios V.

doi:10.1021/ie030457s

Cited by 59 publications

(117 citation statements)

References 12 publications

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“…Until now, the air flow fields in melt blowing have been researched mostly by methods of computational fluid dynamics (CFD) numerical simulation and experimental measurement. Shambaugh and his co-workers [3][4][5][6][7] have systematically numerical simulated the air flow fields in different kinds of die melt blowing, including slot die, annular die and swirl die. Their numerical simulations obtained the profiles of the whole air flow fields including the profiles of air velocity and temperature.…”

Section: Introductionmentioning

confidence: 99%

Turbulent air flow field in slot-die melt blowing for manufacturing microfibrous nonwoven materials

et al. 2018

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Melt blowing is an industrial approach for producing microfibrous nonwoven materials utilizing high-speed air to attenuate polymer melt. The melt-blowing air flow field which is widely believed to be turbulence determines the process of fiber formation. In this study, the turbulent air flow field in slot-die melt blowing was experimental measured by hot-wire anemometer. The fluctuations of air velocity and temperature, the mean velocity and mean temperature were measured and analyzed; moreover, the relationship between turbulent air flow field and fiber formation in melt blowing was discussed and predicted. In the last part of this paper, the coupling effect of air temperature and velocity was studied tentatively, results showed that air temperature not only had an enhanced effect on velocity, but contributed to the fluctuation of velocity. This work shows that the fluctuating characteristics of air velocity and temperature have dominant effect on fiber motion and the evenness of fiber diameter.

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Section: Introductionmentioning

confidence: 99%

Turbulent air flow field in slot-die melt blowing for manufacturing microfibrous nonwoven materials

et al. 2018

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“…The z-axis coincides with the axis of spinning. Experimental studies of the other authors [6][7][8] indicate that the impact of a single row of super-thin polymer streams (filaments) on the air jet dynamics can be omitted. Then, we apply distributions of the aerodynamic fields predetermined at the absence of the filaments as the air velocity, temperature and pressure fields at the pneumatic process.…”

Section: Modeling Of the Air Jet Dynamicsmentioning

confidence: 99%

“…The mathematical model of the melt air-drawing, Eqs. (1)- (3), (5), (6), (11), (12), leads to five first-order differential equations for the axial profiles of the filament temperature T (z), velocity V (z), tensile force F (z), degree of crystallinity X(z), and the rheological extra-pressure p rh (z). Runge-Kutta numerical integration procedure has been used to compute the profiles.…”

Section: Modeling Of Pneumatic Melt Drawing Of Polypropylene Super-thmentioning

confidence: 99%

Modeling of pneumatic melt drawing of polypropylene super-thin fibers in the Laval nozzle

Blim¹,

Jarecki²,

Błoński³

2014

Bulletin of the Polish Academy of Sciences: Technical Sciences

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Abstract. Melt spinning of the fibers by supersonic air jet in the Laval nozzle is a novel, efficient and energy saving method of formation of super-thin fibers. In the process, polymer melt is extruded from a row of orifices and fast drawn by the pneumatic forces. In the modelling, air velocity, temperature and pressure distributions are computed from the k-ω aerodynamic model. Computations of the polymer air-drawing dynamics are based on the mathematical model of melt spinning in a single-, thin-filament approximation and Phan-Thien/Tanner non-linear viscoelasticity of the polymer melt. Axial profiles of the polymer velocity, temperature, tensile stress and rheological extra-pressure are computed. Influence of the Laval nozzle geometry, initial air compression, an initial melt temperature, a polymer mass output and the diameter of the melt extrusion die is discussed. The role of the polymer molecular weight, melt viscosity and relaxation time is considered. Example computations show the influence of important processing and material parameters. In the supersonic process, a high negative internal extra-pressure is predicted in the polymer melt under high elongation rates which may lead to cavitation and longitudinal burst splitting of the filament into a high number of sub-filaments. A hypothetical number of sub-filaments at the splitting is estimated from an energetic criterion. The diameter of the sub-filaments may reach the range of nano-fibers. A substantial influence of the Laval nozzle geometry is also predicted.

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“…The air flow is assumed to be turbulent and a realizable k-e model (Collie et al, 2001) with a standard wall function is used. For additional examples of the application of CFD to melt-blowing modeling, see the work of Krutka et al (2002Krutka et al ( , 2003Krutka et al ( , 2004Krutka et al ( , 2008.…”

Section: Non-isothermal Casementioning

confidence: 99%