Spinning Nozzle Research Articles

Effects of structural parameters on air consumption and mechanical energy characteristics of airflow in the vortex spinning nozzle

Reducing energy consumption during textile production processes has currently become one of the key concerns. In order to design the nozzle of the vortex spinning machine with reduced air consumption, numerical simulation of the airflow in the nozzle is performed to investigate the effect of the length and the inlet diameter of the conical chamber in the intermediate section of the vortex tube on the air consumption and the mechanical energy characteristics of the airflow. A spinning experiment conducted to measure the flow rate and yarn tenacity is adopted to verify the numerical simulation results. The simulation results show that the air consumption of the nozzle is insignificantly affected as the length increases from 7.3 mm to 7.7 mm, while a decreasing trend has been found as the length increases from 7.7 mm to 8.1 mm. As the inlet diameter increases from 4.6 mm to 5.0 mm, the air consumption of the nozzle increases monotonically. The mechanical energy of airflow in the nozzle exhibits a minor difference between cases of lengths of 7.3 mm, 7.5 mm, and 7.7 mm, while it decreases significantly in cases of lengths of 7.9 mm and 8.1 mm. The mechanical energy of airflow in the vortex chamber increases as the inlet diameter increases. The experimental results are consistent with the numerical predictions. This work is expected to provide a reference for the design of the vortex spinning nozzle and an approach to reducing the energy consumption in the yarn production process.

Enhancing airflow dynamics in airjet spinning: A machine learning approach to optimize nozzle design

This research delves into using machine learning techniques to enhance the airflow dynamics in Airjet spinning. It focuses on understanding the factors that affect airflow by examining components of a spinning nozzle including the fiber inlet element, injector nozzle and spinning spindle. A prototype Airjet spinning nozzle was developed to evaluate the Intake Airflow and Airflow Rate, which serve as the basis for a simulation model. A total of 501 data points were empirically gathered, and machine learning methods were applied to uncover patterns and make predictions. The study combines conventional measurement techniques with data analysis tools, like linear regression, decision trees, random forest and support vector regression. After developing a applicable machine learning tool, the hyperparameters are optimized with the goal to improve the model’s reliability. Following this optimization process it was found that the CatBoost model outperformed ML models in terms of all performance metrics. Furthermore insights, into how nozzle features impact airflow dynamics were obtained through sHapley Additive exPlanations (SHAP) analysis. The results indicate that specific nozzle design parameters play a significant role in improving airflow dynamics. Integrating machine learning techniques into the design process marks a departure from conventional empirical methods. This scientific method allows for a more rapid and precise Airjet nozzle design process, fostering innovation in textile manufacturing technology.

Numerical simulation and experimental research of fiber motion in vortex spinning

The application of high speed air flow in the textile field represents the frontier development direction in this field. However, the coupling mechanism between air flow and fiber is extremely complicated which greatly limits the development and application of new textile technologies. For this reason, this research study is intended to focus on the common cutting-edge basic scientific problem of the air-flow-fiber coupling mechanism, the vortex spinning technology is taken as a breakthrough point for research. Three-dimensional numerical models of air flow in vortex spinning nozzle and a free-end fiber were established. The hybrid grids including the structured hexahedral grids and the unstructured tetrahedral grids were used to divide the air-flow computational region, the realizable κ- ε model was used to solve the turbulent characteristics of air flow, and the wall function method was used to solve the air flow in the near wall region. The displacement and deformation of a single free-end fiber under the action of the air-flow force was solved by the second-order nonlinear double asymptotic method and interpolation method. The dynamic twist process of a free-end fiber was simulated in three-dimensional space by taking into account the fiber characteristics, such as straightening, bending, and torsion. In addition, a high magnification microscope was used to observe the free-end fiber motion during the spinning process. The results show that the numerical simulation is consistent with the experimental observation, proving that dynamic numerical simulation can solve difficult problems in the unobserved dynamic twisting process, and this deepens the understanding of the spinning mechanism in vortex spinning.

Orthogonal Optimization Research on Various Nozzles of High-Speed Centrifugal Spinning.

High-speed centrifugal spinning is a burgeoning method of fabricating nanofibers by use of the centrifugal force field. This article studied four different spinning nozzles, which were called stepped nozzle, conical-straight nozzle, conical nozzle, and curved-tube nozzle, to explore the optimal nozzle structures for fabricating nanofibers. According to the principle of centrifugal spinning, the spinning solution flow states within the four nozzles were analyzed, and the solution outlet velocity model was established. Then, the structural parameters of the four kinds of nozzles were optimized with the spinning solution outlet velocity as the test index by combining the orthogonal test and numerical simulation. Based on the orthogonal test results, the influence of nozzle structure parameters on the solution outlet velocity was analyzed, and the best combination of parameters of the centrifugal spinning nozzle structure was obtained. Subsequently, the four kinds of nozzles were used to fabricate nanofibers in the laboratory, under different solution concentration, motor rotation speed, and outlet diameters. Finally, the scanning electron microscope (SEM) was applied to observe the morphology and surface quality of nanofibers. It was found that the surface of nanofibers manufactured by the conical-straight nozzle and curved-tube nozzle was smoother than that by stepped and conical nozzles, and the fiber diameter by the conical-straight nozzle was minimal, followed by curved-tube nozzles, stepped nozzles, and conical nozzles in the diameter distribution of nanofibers.

Combinational biomimetic microfibers for high-efficiency water collection

• Novel spinning method is developed for controllable generation of knotted microfibers. • Microfibers with single or combinational bionic structures are flexibly constructed. • Single biomimetic microfibers show superior water transport and hanging ability. • Combinational biomimetic microfibers reveal enhanced water collection efficiency. Collecting water from fog by microscale fibrous materials is a promising solution to the global water scarcity crisis. However, the previously designed fog harvesting microfibers solely imitate the characteristic structure of the wetted spider silk and have a limited water collection ability. To improve the water collection efficiency, we introduce a dynamic interfacial spinning (DIS) process to fabricate a novel type of fog harvesting microfibers that combine multiple biomimetic structures. Specifically, the DIS process utilizes a tunable vibration of the spinning nozzle at the air–liquid interface to facilitate the facile and controllable generation of the spider-silk-like microfibers consisting of periodic spindle knots and slender joints. Attributed to their distinct surface topography and unique geometric structure, the resultant microfibers have revealed a water transport velocity of 405 times more than that of natural spider silk and a water hanging ability of 4.7 times more than that of the previously reported knotted fibers. With parallel assembly of multiple spinning nozzles, the DIS process produces biomimetic microfibers that combine the water collection feature of the spider silk and the water transport feature of the cactus spine. The resultant microfibers have revealed a water collection efficiency of 1.74 times more than that of previously reported artificial spider silks. Our studies imply that the DIS method opens up an innovative way of constructing biomimetic microfibers for the improved fog harvesting performance.

Modeling the airflow field of vortex spinning

Vortex spinning technology adopts a high-speed swirling airflow to rotate the fibers with open-ends to form yarn with real twists. The airflow behavior within the nozzle has a great effect on the yarn-formation process. In this study, a three-dimensional calculation nozzle model and corresponding three-dimensional airflow region model were established to enable the numerical calculation; airflow behavior—pressure, velocity, and the turbulent airflow field, and the streamline of airflow—was investigated in the presence of fiber bundles within the vortex spinning nozzle. Hybrid hexahedral/tetrahedral control volumes were utilized to mesh the grids in the calculation region. To consider airflow diffusion and convection in the nozzle, the Realizable k- ε turbulence model with wall function was adopted to conduct the calculation. Dynamic and static pressure values were obtained by numerical analysis to predict the action of the inner surface of nozzle and the wall resistance on the high-speed swirling airflow. The numerical simulation of dynamic airflow behavior can generate great insight into the details of airflow behavior and its distribution characteristics, and is helpful for understanding the spinning mechanism and promoting optimization of the spinning process.

Effect of nozzle inlet parameters on the dry granulation atomization process of Si3N4 ceramic bearing balls

In this paper, the atomization characteristics of Si3N4 ceramic dry granulation affect the performance of Si3N4 ceramic bearing balls. In order to improve the dry granulation characteristics and the comprehensive performance of Si3N4 ceramic bearing balls, the atomization mechanism of the spinning nozzle used for Si3N4 dry granulation was studied in detail. The interaction between air and binder in the pressure-swirl nozzle is analyzed based on VOF method, the modified realizable [Formula: see text] turbulence model is used to simulate the flow field inside and outside the pressure-swirl nozzle, the effects of nozzle inlet parameters including the number of tangential inlets and the deflection angle of tangential inlets on the binder volume fraction, velocity distribution and pressure distribution are analyzed. The results show that when the number of tangential inlets increases from 1 to 4, the swirl strength of gas–liquid two-phase in the nozzle increases, the mean diameter of air core increases from 1.51[Formula: see text]mm to 2.01[Formula: see text]mm, and the spray cone angle increases from 18.5[Formula: see text] to 26.4[Formula: see text]. Besides, when the deflection angle of tangential inlet increases from 0[Formula: see text] to 15[Formula: see text], the swirl strength of gas–liquid two-phase in the nozzle with the deflection angle of tangential inlet of 10[Formula: see text] is the largest, and the mean diameter of air core and spray cone angle is 3.04[Formula: see text]mm and 30.7[Formula: see text], respectively. Based on the atomization experiment platform of the electric control fuel system, the mean diameter of air core and spray cone angle are measured, the micromorphology of Si3N4 particles is observed, which verifies the correctness of numerical simulation. When the Si3N4 particles are prepared by dry granulation, taking the atomization performance of nozzle into consideration, the pressure-swirl nozzle with 4 tangential inlets and 10[Formula: see text] deflection angle should be selected.

Research on rotary nozzle structure and flow field of the spinneret for centrifugal spinning

AbstractHigh‐speed centrifugal spinning is a novel method of fabricating nanofibers by use of centrifugal force field. The neoteric designs and proper structural parameters of spinning nozzle will change the outlet velocity and velocity distribution uniformity of spinning solution, which could affect the quality of nanofibers. Four different spinning nozzles that can be used for high‐speed centrifugal spinning are proposed. The flow of spinning solution in the different rotary nozzles is simulated based on the theoretical analysis. It can be found that the curved‐tube nozzle is better for high‐speed centrifugal spinning comparing with the velocity distribution of spinning solution in the four different spinning nozzles. The influence degree of the structure parameters of the curved‐tube nozzle on the solution outlet‐velocity is explored by orthogonal test method. The result shows that the curved‐tube nozzle with an inlet diameter of 10 mm, conical transition pipe length of 3 mm, nozzle outlet diameter of 0.8 mm, curvature radius of 4 mm, and central angle of curved tube of 30°, can effectively enhance the outlet velocity of spinning solution. Finally, it is proved by centrifugal spinning experiment that the curved‐tube nozzle after optimization can improve the morphology and quality of nanofibers.

Solution Blow Spinning of High-Performance Submicron Polyvinylidene Fluoride Fibres: Computational Fluid Mechanics Modelling and Experimental Results.

Computational fluid dynamics (CFD) was used to investigate characteristics of high-speed air as it is expelled from a solution blow spinning (SBS) nozzle using a k-ε turbulence model. Air velocity, pressure, temperature, turbulent kinetic energy and density contours were generated and analysed in order to achieve an optimal attenuation force for fibre production. A bespoke convergent nozzle was used to produce polyvinylidene fluoride (PVDF) fibres at air pressures between 1 and 5 bar. The nozzle comprised of four parts: a polymer solution syringe holder, an air inlet, an air chamber, and a cap that covers the air chamber. A custom-built SBS setup was used to produce PVDF submicron fibres which were consequently analysed using scanning electron microscope (SEM) for their morphological features. Both theoretical and experimental observations showed that a higher air pressure (4 bar) is more suitable to achieve thin fibres of PVDF. However, fibre diameter increased at 5 bar and intertwined ropes of fibres were also observed.

High Efficiency Fabrication of Chitosan Composite Nanofibers with Uniform Morphology via Centrifugal Spinning.

While electrospinning has been widely employed to spin nanofibers, its low production rate has limited its potential for industrial applications. Comparing with electrospinning, centrifugal spinning technology is a prospective method to fabricate nanofibers with high productivity. In the current study, key parameters of the centrifugal spinning system, including concentration, rotational speed, nozzle diameter and nozzle length, were studied to control fiber diameter. An empirical model was established to determine the final diameters of nanofibers via controlling various parameters of the centrifugal spinning process. The empirical model was validated via fabrication of carboxylated chitosan (CCS) and polyethylene oxide (PEO) composite nanofibers. DSC and TGA illustrated that the thermal properties of CCS/PEO nanofibers were stable, while FTIR-ATR indicated that the chemical structures of CCS and PEO were unchanged during composite fabrication. The empirical model could provide an insight into the fabrication of nanofibers with desired uniform diameters as potential biomedical materials. This study demonstrated that centrifugal spinning could be an alternative method for the fabrication of uniform nanofibers with high yield.

Controllable generation of nanofibers through a magnetic-field-assisted electrospinning design

Electrospinning technology is taken as the most versatile process to generate continuous nanofibers. However, effects should be taken to achieve better understanding and precisely control the actual mechanics in the formation of nanofibers through better system design. In this article, the diameter and the deposition area of the as-prepared nanofibers can be controlled by added helix tube which can provide external electric-magnetic field. The spinning process can be controlled employing a magnetic flux (B) analytical model which is based on the magnetic field calculation modelof the solution and the electrostatic charge repulsion in the jet. This method includes the thermo-mechanical properties based on as-prepared electrospun nanofiber films and the capability of tribology-mechanical and mathematical physics. A novel investigation of the whole output increase at per unit spinning area is presented in this article to describe the whipping instability which is an important feature of the Taylor Cone phenomenon. The present design and process for electrospinning are based on a solution differential calculus, which a single stainless steel spinning nozzle can generate multi-squirt flow. With the purpose of providing useful jet initial behaviour design for the further technology applications, we attempt to set up a differential calculus method with evenly distributed circumferential electric field, yet giving more design guidance to produce controllable nanofibers through magnetic-field-assisted electrospinning technology.

Numerical investigation on the flow field of a modified vortex spinning system for producing core-spun yarns

A modified vortex spinning technology, which produces core-spun yarns by means of a tangentially injected swirling airflow, is of great prospect in view of its production rate and yarn structure. In this paper, a numerical study based on computational fluid dynamics is presented to investigate the characteristics of the flow field of this system. In the simulation, the effect of the rotating front rollers on the flow field is taken into consideration. Flow characteristics inside the spinning nozzle, flow field of the front rollers, and streamline patterns have been revealed. The results show that a high-speed swirling flow is generated in the near-wall region in the nozzle chamber due to the ejection of air-jets from the tangential injectors. An asymmetric sub-pressure zone is formed in the core region of the nozzle chamber where the interactions of the high-speed swirling flow and three streams of secondary flows generate three vortices. Airflows in the vicinity of the front rollers generally converge toward the nozzle entrance from all directions except those in the boundary layer of the front roller surfaces, which is helpful for the delivery of fibers into the nozzle. A vortex is formed above the top roller and another beneath the bottom roller. The results of the streamline patterns show that the flow characteristics of the modified vortex spinning can facilitate the formation process of the core-spun yarn, which presents a qualitative explanation to the dynamic behavior of the fibers that was experimentally obtained.

RAPID VISUALIZATION OF THE MASS DISTRIBUTION PROFILE OF ELECTROSPUN LAYERS

Nanofibrous materials are currently widely used in many different areas. One of the technologies commonly used for their production is electrospinning. The mass distribution in a produced nanofibrous layer is a crucial factor especially for filtration applications and active ingredients or drug release applications. Image analysis is an efficient non-destructive method of a mass distribution determination, which has already been used in the evaluation of textiles and melt-blown webs, but so far only a few publications have dealt with its use in the field of electrospun materials. To facilitate the process of image analysis of deposited nanofibers, we developed a new collector electrode, which makes it possible to determine the optical mass distribution profile of the produced layer. A series of experiments proved that the developed collector allows an easy evaluation of the appearance of nanofibrous layers as well as the effects of many associated factors such as emitter configuration on the resulting sample. The results showed how the properties of nanofibrous layers (such as deposition zone dimensions, location of these zones, mass distribution profiles produced by different spinning nozzles) can change during the electrospinning process. The advantages of the method described in the present article are that it allows a contactless and non-destructive determination of mass distribution, detection of macroscopic defects, and investigation of causes behind layer thickness inhomogeneities. All in all, the presented method is a useful research and development tool for the field of electrospinning.

A core-spun yarn containing a metal wire manufactured by a modified vortex spinning system

A core-spun yarn containing an ultrafine copper wire for wearable electronics-oriented applications has been manufactured using a modified vortex spinning system for the first time. The copper wire is fed into the spinning nozzle through a groove on the surface of the top front roller and an orifice through the fiber guiding member in sequence. Scanning electron micrographs confirm that the copper wire locates in the core region and is tightly wrapped by the helical staple fibers of the outer layer in the core-spun yarn, owing to the special yarn formation mechanism of the vortex spinning system. The vortex core-spun yarn containing a copper wire has a strength higher by 86.6% and a breaking extension lower by 70.2% compared to the copper wire, while its strain sensitivity in the workable strain range is not affected by either the yarn manufacturing process or the existence of staple fibers. The vortex core-spun yarn containing a metal wire could be a promising candidate for the conductive tracks of wearable electronics due to its improved structure, durability, and comfort.

The effect of polarity in the electrospinning process on PCL/chitosan nanofibres' structure, properties and efficiency of surface modification

The aim of this research was to study the effect of charge polarity applied to the spinning nozzle on the structure and properties of polycaprolactone/chitosan (PCL/CHT) blends, in particular the efficiency of further surface modification by chondroitin sulphate (CS). The observed differences in the morphology and properties of fibres formed at different polarities were interpreted in terms of molecular interactions occurring in the system. FTIR results indicate stronger PCL-chitosan interactions at negative polarity, resulting in lower PCL crystallinity and crystal size distribution determined by DSC, as well as lower wettability. The charge polarity influences PCL/CHT fibre morphology and tailors some of their properties, e.g. wettability, mechanical properties and the efficiency of surface modification. Better efficiency of CS attachment was observed at negative polarity using atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) is most probably related to higher chitosan content at the fibres' surface being attracted by the negative external potential.

Numerical simulation of swirling airflow dynamics in vortex spinning

In this paper, a computational fluid dynamics model has been established and a three-dimensional numerical simulation of the flow characteristics of airflow in a vortex spinning nozzle has been carried out. A realizable k-ɛ model is used to simulate the turbulence of airflow in the nozzle. Unstructured tetrahedral grids which have good adaptability to complex boundaries are used in this paper to mesh the computational region. The computational model of the airflow field is solved and the characteristics of airflow in a vortex spinning nozzle are obtained. The results show that the flow principle of the airflow is determined by the pressure distribution of the airflow. The airflow field in the nozzle can be divided into external and internal areas, according to the flow characteristics and functions of airflow. The trajectory of swirling airflow from the jet orifices has a regular rotational motion within the twisting chamber, but the trajectory of swirling airflow from nozzle inlet is complex and backflow occurs; finally, these two strands of airflow are fused together as a regular rotational motion.

Numerical simulation of the yarn formation process in Rieter air jet spinning

This paper presents a three-dimensional numerical simulation of the airflow field inside Rieter air jet spinning nozzle. The velocity and pressure distribution were analyzed to describe the principle of yarn formation. The analysis of velocity components and static pressure revealed how the air vortices are created inside the nozzle. A theoretical study along with experimental verification was performed to investigate the influence of nozzle pressure on air jet yarn tenacity and the results were in good agreement. The results show that increasing nozzle pressure resulted initially in improving yarn tenacity but at high pressure tenacity deteriorates.

Fine Filament Formation Behavior of Polymethylpentene and Polypropylene near Spinneret in Melt Blowing Process

Abstract Formation behavior of fine fibers of polymethylpentene (PMP) and polypropylene (PP) in the melt blowing process was investigated through the observation of the spin-line near the spinning nozzle using a high speed camera. Reduction of the polymer throughput rate and increase of the air flow rate were necessary to achieve fine diameter fibers, however these conditions generally cause the instability in the spinning process. Observation of the spin-line at the melt blowing die revealed the periodic accumulation of polymer flow near the spinning nozzle followed by the quick pulling down of the accumulated polymer by the air flow. This behavior caused the periodic fluctuation of fiber diameter as well as the intermittent breakage of the spin-line under extreme conditions. Because of high extrusion viscosity, PMP showed more stable spinning behavior than PP. Frequency of diameter fluctuation became higher with the increases of air flow rate and throughput rate, and the maximum frequency of about 60 Hz was observed for PP spinning with the throughput rate of 0.18 g/min. Diameter distribution of the fibers in the prepared web was also analyzed to compare with the spinning behavior. Fiber diameter distributions were narrow and symmetric under stable spinning conditions, whereas skewed diameter profiles with a maximum at low value and a long tail to the larger diameter region were observed under unstable conditions. Intermittent spin-line breakage caused flaws of “shot” and/or “fly”, and the skewed fiber diameter distribution with the presence of a small amount of fiber of extremely large diameter was confirmed.

Morphological variations of micro-nanofibrous sorbents prepared by electrospinning and their effects on the sorption of crude oil

Crude oil spills have both a high environmental and economic impact, ensuring that its removal is an international concern. To aid in its removal, sorbents make of pure and recycled polystyrene (PS) polymers in the form of microfibers have been utilized in this regards. With an electrospinning (ES) technique used to make the fibrous sorbents. These sorbents have both a high surface area and a high degree of hydrophobicity. The effects of varying the electrospinning parameters, on the affinity of the fibrous sorbents prepared thereafter toward oil spills in artificial polluted seawater media was investigated. Such parameters include the polymer type, solvent type, applied voltage, feeding rate, spinning distance, degree of relative humidity and the internal diameter of the spinning nozzles. Results showed a strong correlation between fiber characteristics and their affinity toward the sorption of oil spills. A step-by-step optimization of the electrospinning parameters was shown to enhance the performance of the fibrous sorbents toward the treatment of crude oil spills.

Effects of structural parameters on the tangentially injected swirling flow in concentric tubes with different lengths as a model of the vortex spinning nozzle

The tangentially injected swirling tube flow has broad applications in various engineering fields. In the textile industry, the vortex spinning technology, which produces short-staple yarns by means of a tangentially injected swirling airflow, is of great prospect in view of its spinning speed and yarn structure. In this paper, the vortex spinning nozzle is abstracted into a model of concentric tubes of different lengths with tangential injectors. A computational fluid dynamics model is presented to study the effects of some structural parameters on the swirling flow generated in this tube system. The particle image velocimetry (PIV) technique is adopted to measure the flow field. Due to the difficulty in duplicating the Mach number, Reynolds numbers are matched between the tube model and prototype in the PIV experiment. Despite the discrepancy between the velocity values provided by the numerical simulation and experiment due to the compressibility effects not being reproduced in the PIV measurement, a comparative analysis concludes that qualitatively matched results on the flow pattern and effects of the structural parameters are obtained by the numerical simulation and PIV measurement.