纺粘非织造窄狭缝牵伸器喷射流场的研究与分析

建立了纺粘窄狭缝牵伸器喷射流场的理论模型,采用有限差分法对该模型求解,采用SIMPLE算法求解速度和压力耦合,用交错网格解决速度和压力的锯齿状分布问题,差分格式为二阶迎风格式,使用交替方向的逐线TDMA方法求得差分方程。数值计算得到了气流速度在x方向上的分量,与实验结果吻合较好。通过对几种纺粘牵伸器喷嘴的喷射流场进行了数值模拟,给出了相应的流场矢量图,显示了该研究在对纺粘设备进行计算机辅助设计方面的应用前景。     

纺粘工艺参数和牵伸器设计几何参数对纤维直径的影响

建立了纺粘聚合物气流牵伸模型，采用计算机数值模拟方法求解牵伸器的喷射流场，分析了纺粘工艺参数和牵伸器设计几何参数对纤维直径的影响，得出了影响规律。     

纺粘牵伸器喷射流场的测试及验证

根据纺粘非织造扁平窄狭缝流道牵伸器的特点和喷射流场的特征,采用粒子图像测速仪对纺粘牵伸器的喷射流场进行了试验测试,同时,列出用喷射流场理论模型所获得的计算数值模拟结果,并对数值模拟结果和试验结果进行比较。     

纺黏非织造牵伸器喷射流场的数值模拟和牵伸器优化设计

根据纺黏非织造牵伸器的特点和喷射流场的特征,采用粒子图像测速仪对纺黏牵伸器的喷射流场进行了试验测试,同时,相应列出用喷射流场的理论模型有关理论和方法所获得的计算数值模拟结果,并对数值模拟结果和试验结果进行比较。最后对5种设计的牵伸器的几何形状及气流速度沿牵伸器长度方向分布情况进行了分析。     

纺粘非织造布牵伸器工艺设计初步探讨

管式气流牵伸器是涤纶纺粘非织造布工程的核心设备,选择合适的牵伸器,不仅能提高产品质量,还能降低生产成本。在拟定纺制单丝纤度为0.75 dtex、纺速为5000 m/min的前提下,选择进气压力为0.4 MPa、喷口缝隙为0.4 mm的工艺条件,进行气流试验和带丝试验,试验结果显示:拉伸效果较好,能耗较低。     

聚合物熔体在纺黏非织造牵伸器中的气流牵伸模型 与数值模拟研究

介绍了有关纺黏非织造过程建模与数值求解的方法。首先在继承前人研究成果的基础上,给出了纺黏非织造过程理论模型;其次,对实际生产中应用的宽狭缝牵伸器的喷射流场进行数值模拟,求出了气流速度在牵伸器中的数值分布。通过对牵伸器喷射流场的数值模拟,得到了气流速度在流场中的数值分布,从而为聚合物熔体的气流牵伸模型求解提供了有利的条件。本研究也显示了在对纺黏非织造布工艺和设备进行计算机辅助设计方面具有较好的应用前景。     

水刺加固喷嘴高速喷射流场的数值模拟及验证

以水刺加固喷嘴高速射流对聚合物纤维进行水力缠结加固成形的过程为研究对象,通过建立水刺加固喷嘴喷射流场理论模型,经过数值模拟研究了4个不同水刺加固喷嘴高压喷射流场的运动特征,并与粒子图像测速仪系统测试的结果进行了对比。结果表明：采用Realizable k-ε湍流模型描述水刺工艺水腔内喷嘴的喷射流场正确,建立的数值模拟计算求解方法有效,与实验测试值十分吻合;适当增大喷嘴喷口的高度,可使流体在喷嘴喷口轴向方向的速度增大;适当增大射流初始段的长度,可使流体的流量和压力增大,提高水刺非织造纤维网缠结效果;随着射流过渡段长度的增大,混合段(即过渡段和充分发展段)出口压力增大,喷射流体的速度增大,纤维网所受到的冲击力增大;适当减小喷嘴过渡段高度,混合段出口处压力增大,可以实现较大范围内喷射流体速度的增大,改善水刺非织造纤维网缠结效果。     

熔喷法气流拉伸机理与喷射流场的研究进展

介绍了熔喷法非织造布的气流拉伸机理和空气喷射流场的研究进展,评价了聚合物熔喷气流拉伸的数学模型和空气喷射流场等对纤维直径的影响。指出今后的研究应探索建立熔喷法的三维拉伸模型和喷嘴气流喷射流场理论。     

聚合物纺粘气流拉伸与射流性能的研究进展

叙述了纺粘法非织造布气流拉伸机理和水刺法中纤网射流性能等研究的进展;分析和评价了聚合物纺粘气流托伸的数学模型、水刺喷嘴对射流特性以及水刺纤网射流加固对水刺布质量等的影响,这也是纺粘法非织造布技术今后的研究方向。     

纺黏非织造牵伸器喷射流场理论模型的建立

讨论了纺黏非织造牵伸器喷射流场理论模型的建立,包括4种湍流模型的选择,模型的控制方程和边界条件、控制方程的通用形式等。     

Computational fluid dynamics simulation and theoretical study the air jet flow field of a wide slot positive pressure drawing assembly in the spunbonding nonwoven process

The polymer air‐drawing model of polyethylene terephthalate spunbonding nonwovens and the air jet flow field model in wide slot positive pressure spunbonding process have been established. The influence of the density and the specific heat capacity of polymer melt at constant pressure changing with polymer temperature on the fiber diameter have been studied, which is solved by introducing the numerical computation results of the air jet flow field of attenuator. It is simulated by means of the finite difference method. The predicted fiber diameter agrees with the experimental data. The effects of the processing parameters on the fiber diameter with the help of the image analysis method have been investigated. A higher inlet pressure, smaller slot width, and smaller jet angle will all cause higher z‐axis position of air velocity and air pressure, which are beneficial to the air drawing of the polymer melt and thus to reducing the fiber diameter. The experimental results show that the agreement between the results and experimental data is better, which verifies the reliability of these models. The results present great prospects for this research in the field of computer assisted design of spunbonding process, technology, and equipment. POLYM. ENG. SCI., 55:231–242, 2015. © 2014 Society of Plastics Engineers     

Numerical modeling,simulation, and experimental validation of predicting fiber diameter in wide‐slot positive‐pressure spunbonding process

An air‐drawing model of polypropylene (PP) polymer and an air jet flow field model in wide‐slot positive‐pressure spunbonding process are established. The influences of the density and the specific heat capacity of polymer melt at constant pressure changing with polymer temperature on the fiber diameter have been studied. The predicted fiber diameter agrees with the experimental data as well. The effects of the processing parameters on the fiber diameter have been investigated. The air jet flow field model is solved by means of the finite difference method. The numerical simulation computation results of distribution of the fiber diameter match quite well with the experimental data. The air‐drawing model of polymers is solved with the help of the distributions of the air velocity. It can be concluded that the higher air velocity and air temperature can yield the finer fibers diameter. The higher inlet pressure, longer drawing segment length, smaller air knife edge, longer exit length, smaller slot width, and smaller jet angle can all cause higher air velocity and air pressure along z‐axis position, which are beneficial to the air drawing of the polymer melt and thus to reduce the fiber diameter. The experimental results show that the agreement between the predicted results and the experimental measured data is very better, which verifies the reliability of these models. Also, they reveal great prospects for this work in the field of computer‐assisted design (CAD) of spunbonding process. POLYM. ENG. SCI., 58:1371–1380, 2018. © 2017 Society of Plastics Engineers     

Computer‐aided mathematical modeling and numerical simulation and theoretical analysis of the polypropylene polymer air drawing in spunbonding nonwoven process

In this article, as a nonlinear mathematical problem, the air‐drawing model and the air jet flow field model of the polymer during spunbonding process are also presented, because the continuous filament fiber not always occurs in the spunbonding process, therefore, there exists the filament fiber breakage, the broken fibers occur in the flow field of spunbonding process is a two‐phase flow problem, we suggested a new model called the sphere–spring model that can best described the broken fibers movement features. At the same time, the air‐drawing model of the polypropylene polymer in a spunbonding process is presented and solved by introducing the numerical computation results of the air jet flow field of aerodynamic device. The model's predictions of the filament fiber diameters, crystallinities, and birefringences are coincided well with the experimental data. The effects of the processing parameters on the filament fiber diameter are discussed. A lower polymer throughput rate, lower quench air temperature, higher polymer melt initial temperature, higher air initial temperature, higher air initial speed, medium smaller venturi gap, higher air suction speed, higher quench air pressure, higher air suction speed, higher extrusion temperature, higher quench air pressure, higher cooling air temperature, and so on can all produce finer filament fiber. The results show great prospects for this research in the field of computer‐assisted design of spunbonding technology. POLYM. ENG. SCI., 54:481–492, 2014. © 2013 Society of Plastics Engineers     

Influence of processing parameters on fibers diameter and web evenness of polypropylene spunbonding nonwoven fabrics in wide slot positive pressure drafting assembly of spunbonding process

The air drawing model of polymer polypropylene (PP) spunbonding nonwovens has been established. The influences of the density and the specific heat capacity of polymer melt at constant pressure changing with polymer temperature on the fiber diameter have been studied. The air drawing model of polymer in spunbonding is confirmed by the experimental results obtained with our university's equipment. The effects of the processing parameters on fibers web evenness of PP spunbonding nonwoven fabrics in wide slot positive pressure drafting assembly of spunbonding process have also been investigated. The predictions of the filament fiber diameters, crystallinities, and birefringences are coincided well with the experimental data. It is found that a medium polymer melt temperature, monomer suction wind speed, drawing pressure, cross air blow speed, and air control distance have a significant influence on the web evenness and quality, which are beneficial to produce more uniformity fibers web. The experimental results show that the agreement between the results and experimental data is very better, which verifies the reliability of these models. At the same time, the results also reveal the great potential of this research for the computer‐assisted design (CAD) of spunbonding technology. POLYM. ENG. SCI., 58:1268–1277, 2018. © 2017 Society of Plastics Engineers     

Experimental study and numerical simulation the air jet flow field of a dual slot sharp blunt die in the melt blowing nonwoven process

In this work, the physical model of a polymer in a melt blowing process is established and solved by introducing the numerical computation results of the air jet flow field of the dual slot sharp inset die. The influence of the melt blowing processing parameters and the die design parameters on the fiber diameter is also studied. A lower polymer throughput rate, higher polymer melt initial temperature, higher air initial temperature, higher air initial velocity, smaller angle between slot and axis of the spinneret, smaller width of the die head, and larger width of the slot can all produce finer fibers. At the same time, the air jet flow field model of the dual slot sharp inset die of polypropylene polymer nonwovens fabrics in melt blowing process was also established. The air jet flow field model was solved by using the finite difference method. The computational simulation results of the distributions of the z‐components of air temperature and air velocity along the spinline during melt blowing process are in accordance with the experimental data. The air drawing model of melt blowing process was simulated by means of the numerical simulation results of the air jet flow field. The predicted fiber diameter agree with the experimental data. The effects of the air initial velocity and air initial temperature on the fiber diameter were studied and discussed. The results demonstrate that a higher air initial velocity and a higher air initial temperature are beneficial to the air drawing of the polymer melt and thus to reduced fiber diameter. The results show the great potential of this research for computer assisted design in melt blowing nonwoven process and technology. POLYM. ENG. SCI., 57:417–423, 2017. © 2016 Society of Plastics Engineers     

A numerical computation and experimental study of air drawing model of polymers in spunbonding nonwoven process

The air drawing model of polyethylene terephthalate polymer and the model of the air jet flow field in spunbonding process are established. The air jet flow field model is simulated with the help of the finite difference method. The numerical simulation computation results of distributions of the air velocity and air temperature are in agreement with the experimental data. The air drawing model of polymer is solved with the aid of the distributions of the air velocity measured by a particle image velocimetry. The predicted fiber diameters tally with the experimental data well. It can be concluded that the higher initial air temperature can generate finer filament fiber diameter, and the higher initial air velocity can yield the finer fiber diameter as well. The experimental results show that the agreement between the predicted results and the experimental data is very good, which confirms the reliability and the accuracy of these mathematical models. Also, they reveal great prospects for this work in the field of computer assisted design of spunbonding process. POLYM. ENG. SCI., 2013. ©2012 Society of Plastics Engineers     

A physical–mathematical model for the prediction of fiber diameter of the polyethylene terephthalate (PET) spunbonding nonwoven fabrics

A mathematical model of air drawing of a polyethylene terephthalate (PET) polymer in a spunbonding nonwoven process was established and solved by introducing the numerical computational results of the air jet flow field of the attenuator. The predicted fiber diameters, crystallinities, and birefringences agreed well with the experimental data. The air jet flow field model was solved and simulated by means of the finite difference method. The numerical simulation computation results of distributions of the air velocity matched quite well with the experimental data. The air drawing model of the polymer was solved with the help of the distributions of the air velocity measured by a particle image velocimetry. The effects of the processing parameters on the fiber diameters, measured with the aid of an image analysis method, are further discussed. A lower polymer throughput rate, higher polymer melt initial temperature, higher air initial temperature, higher air initial speed, lower venturi gap, higher air suction speed, and higher quench pressure can all produce finer filament fibers. The results demonstrated the great prospects for this research in the field of computer‐assisted design (CAD) in the spunbonding technology field. POLYM. ENG. SCI., 58:1213–1223, 2018. © 2017 Society of Plastics Engineers