Numerical Study on the Solution Blowing Annular Jet and Its Correlation with Fiber Morphology

Abstract

In this work, we investigated the turbulent airflow field of a solution-blowing annular jet using the computational fluid dynamic approach, captured the fiber flapping motion with a high-speed camera, and then correlated the fiber morphology with the physical quantities of the airflow field and fiber motion. The characteristics of the average flow fields of various nozzle configurations under different air pressures were calculated and compared. The simulations demonstrated that higher air pressure results in higher velocity and turbulent fluctuations. The experiments showed that polymer jet attenuation is due to the effects of stretching, bending instability, flapping motion, and solvent evaporation. The fiber diameters were found to decrease and become more uniform as the air pressure increased. However, the fiber morphology became worse, with the emergence of some fiber strands under even higher air pressures.

A Review of the Fundamental Principles and Applications of Solution Blow Spinning

“…(B, C) High-speed photograph comparing the length of the straight region (in red box) of the polymer jet produced by SBS at gas pressures of 1.121 atm (B) and 1.363 atm (C). Adapted with permission from ref 46. Copyright 2014 American Chemical Society.…”

Solution Blow Spinning of Polyvinylidene Fluoride Based Fibers for Energy Harvesting Applications: A Review

“…Therefore, an optimum feed rate is essential to achieve the fibers with minimum diameter. Computational methods have been employed to numerically investigate the influence of air characteristics on the fiber morphology in SBS [100,104]. Experimental studies that investigate airflow parameters for SBS are sparse.…”

“…The flow presents with a recirculation zone of reversed flow directly behind the nozzle where the fiber is attenuated. Lou et al [100] provided velocity plots along the centerline of the nozzle where flow reversal is observed. The flow velocity rapidly increases aft of the recirculation zone to a maximum value and then decreases monotonically.…”

“…Fiber diameter decreased and became more uniform with increasing air pressure. However, the fibers became defective when pressure was further increased [100]. When air is passed through the air inlet and moves toward the nozzle tip, it must be ensured that there is no choking [101].…”

“…To investigate the turbulent behavior of the flow, the k-ε turbulence model is one of the most commonly used models in CFD to simulate mean flow characteristics. This method results in rapid convergence [100] and is effective for solving problems involving reverse flow [105]. It is a semi-empirical model based on model transport equations for the turbulence kinetic energy (k) and its dissipation rate (ε).…”