Influence of Laval nozzles on the air flow field in melt blowing apparatus

Tan, Dawud H.; Herman, Peter K.; Janakiraman, Arun; Bates, Frank S.; Kumar, Satish; Macosko, Christopher W.

doi:10.1016/j.ces.2012.06.020

Cited by 57 publications

(51 citation statements)

References 14 publications

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“…2a) [17], illustrating that the air flow field in melt blowing has obvious characteristic of turbulence. Research group of Kumar and Bates [18][19][20][21][22] has done some theoretical and experimental work on the fiber formation, onset of fiber whipping and fiber breakup as well as utilizing an innovative Laval nozzle in melt blowing, their work had a significant contribution to the research on melt blowing, and they also mentioned that, in melt blowing, whipping-like motion of fiber was due to turbulent air [20]. Furthermore, the fiber motion in melt blowing can indirectly reflects the turbulent characteristic of air flow field.…”

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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“…Thus, it oscillates, accompanied by the formation of compression waves in the supersonic region when the inlet pressure is larger than 15 psi. The simulation demonstrates that a Laval nozzle influences the airflow field by increasing the maximum value of the gas jet velocity and by eliminating the compression waves at specific expected values of the pressure inlet [12].…”

Section: Introductionmentioning

confidence: 94%

“…Tan et al proposed that the inclusion of a Laval nozzle would magnify the velocity and eliminate the instability of the airflow field. They also conjectured that the Laval nozzle was best equipped for high velocity and stable flow fields [12]. Li et al found that the flow generated by the Laval nozzle had a higher exit velocity in the vicinity of the nozzle, compared to a straight nozzle.…”

Section: Introductionmentioning

confidence: 99%

Optimal Nozzle Structure for an Abrasive Gas Jet for Rock Breakage

Liu

Zhang

et al. 2018

Geofluids

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Abrasive gas jet technologies are efficient and beneficial and are widely used to drill metal and glass substrates. When the inlet pressure is increased, gas jets could be powerful enough to break rock. They have potential uses in coal-bed methane exploration and drilling because of their one-of-a-kind nonliquid jet drilling, which avoids water invasion and borehole collapse. Improving the efficiency of rock breakage using abrasive gas jets is an essential precondition for future coal-bed methane exploration. The nozzle structure is vital to the flow field and erosion rate. Furthermore, optimizing the nozzle structure for improving the efficiency of rock breakage is essential. By combining aerodynamics and by fixing the condition of the nozzle in the drill bit, we design four types of preliminary nozzles. The erosion rates of the four nozzles are calculated by numerical simulation, enabling us to conclude that a nozzle at Mach 3 can induce maximum erosion when the pressure is 25 MPa. Higher pressures cannot improve erosion rates because the shield effect decreases the impact energy. Smaller pressures cannot accelerate erosion rates because of short expansion waves and low velocities of the gas jets. An optimal nozzle structure is promoted with extended expansion waves and less obvious shield effects. To further optimize the nozzle structure, erosion rates at various conditions are calculated using the single-variable method. The optimal nozzle structure is achieved by comparing the erosion rates of different nozzle structures. The experimental results on rock erosion are in good agreement with the numerical simulations. The optimal nozzle thus creates maximum erosion volume and depth.

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“…9 for index of non-Newtonian behaviour, has been fitted by the recently proposed generalized Newtonian model (Eqs. [1][2][3][4][5]. The model parameters are summarized in Table 2 and comparison between the experimental data and model prediction is provided in Figure 8.…”

Section: Evaluation Of Generalized Newtonian Modelmentioning

confidence: 99%

“…Thus, the polymer processing operation at which the full rheological polymer sample characterization is very complicated or practically impossible by standard rheological tools is difficult to optimize. The melt blown technology for the polymeric nanofibers production is one of them [3][4][5]. In more detail, polymer melt viscosity during the nanofiber production has to decrease considerably (melt index 450-1600 g/10 min).…”

Section: Introductionmentioning

confidence: 99%