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。     

纺粘法扁平狭缝牵伸器喷射流场的数值模拟

采用标准K-ε模型描述了纺粘法扁平狭缝流道牵伸器喷射流场的湍流运动,利用有限差分法对该模型求解。通过对6种纺粘法牵伸器喷嘴的喷射流场进行数值模拟,得到了相应的流场矢量图。分析流场矢量图发现,适当减小拉伸段宽度,增加喷射喷口长度,适当选择牵伸器喷口宽度和牵伸器的拉伸段长度,有利于提高气流速度,从而有利于对聚合物熔体进行气流拉伸,使纤维直径变细,提高纺粘法成网的质量。     

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。     

纺粘非织造布技术现状与发展

从产品品质、生产效率、复合技术及工程聚合物应用方面简要论述了目前纺粘非织造布技术现状,着重谈及寻求技术合作在纺粘非织造布技术研发中的重要性,并就国内纺粘非织造技术发展和提高企业竞争力提出粗浅看法。     

丙纶纺粘非织造布抗静电整理的工艺研究

采用壳聚糖和阳离子表面活性剂对丙纶纺粘非织造布进行抗静电后整理,考察了抗静电剂种类、浓度、配比、浸渍时间对织物抗静电性能及服用性能的影响。实验表明:复合抗静电剂在低浓度(0.25%￣0.50%)下使用,就可明显提高丙纶纺粘非织造布的抗静电性。对抗静电整理后织物服用性的测试表明:复合抗静电剂对织物的纵横向断裂强度、透气量、悬垂性基本无影响。     

PP/PE双组分纺粘非织造材料的抗渗整理工艺研究

本文研究了整理液浓度、烘焙温度和烘焙时间时PP/PE双组分纺粘非织造布抗渗性能的影响及作用机理,发现PP/PE双组分纺粘非织造布经抗渗整理后,其抗渗性能明显提高.材料的抗渗性能随整理液浓度的增加、烘焙温度的升高和烘焙时问的增加而增强,但超过某一临界值后,材料的抗渗性能反而下降.另外,由于整理过程中的受热作用,整理后材料变厚,强度有所下降.     

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。     

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     

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     

FJCA20型煤用喷射式浮选机流场分布规律的初步研究

以选矿专业理论为基础,运用流体动力学、相似模拟理论及粒子图像(PIV)测试技术,对比分析了FJC和FJCA20型喷射式浮选机浮选室内流场分布特点,为浮选机的研制和发展提供了理论依据。     

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。     

Study on the flow field of the air jet from dual slot die in the melt blowing process

The possibility of describing the jet from the dual slot die in the melt blowing process with a vortex pair was studied according to the nature of the vortex. A model of the synthesis of two jets was developed. The reliability of the model was confirmed by experimental data cited from literature. The prediction of the fiber diameter using this model coincided with that using the fitted equation with the data advanced by Harpham and Shambaugh. The effects of the equipment parameters, such as the angle between the air flow and the axis of the spinneret, the width of the die head and the width of the slot were also discussed.     

单进口后混式射流粉碎中多相流混合机理及加速特性

为了深入了解后混式高速水射流超细粉碎技术,以4种加速管管径条件下的液、气、固三相混合射流为对象,利用数值计算和粉碎实验相结合的方法,研究了多相混合射流相间的混合机理和加速特性,探讨了颗粒在加速空间中的分布规律。结果表明:水射流紊动掺气和卷吸作用是混合附加相的内在机理;混合射流对颗粒的加速存在分区,越靠近势流区冲击能量越大,优化喷嘴直径与加速管管径配置,迫使颗粒靠近或进入该区域可有效提高粉碎产率。颗粒在加速管内的空间分布为外层、内层高效加速区内含量最高,越靠近势流区颗粒含量越少,气流区内颗粒含量随加速管管径增大而增大。颗粒很难进入理想加速区,大部分仍依靠内、外层高效加速区加速。在保持自由射流流动形态的情况下,粉碎产率随加速管管径增大而下降,小管径对水射流能量和颗粒运动空间均具有更好的约束集中作用。