Four Key Breakthroughs In China'S High Efficiency Textile Industry Have Added A Cornerstone For Breakthroughs.

Compared with other first prize projects, Donghua University Spin The Institute's "fiber / high-speed airstream two phase fluid dynamics and its application basic research" belongs to the basic science field of textile science and technology. The most advanced textile universities in China, Professor Yu Chongwen and his team pay more attention to basic science and lay the foundation for the textile industry.

The application of airflow in textile field is very extensive, which runs through the process of fiber forming textiles. The application of high speed airflow has laid a foundation for the emergence and development of new textile technology and technology. With the help of high speed airflow, we can realize the process of conveying, drafting, separating and twisting textile fibers, which has an immeasurable prospect in improving processing efficiency and shortening process flow. Although not many words, Professor Yu Chongwen has clearly outlined the importance of this basic research.

How does a basic research stand out in hundreds of projects? In the strong academic atmosphere of the textile School of Donghua University, members of the project group of "fiber / high speed airstream two phase fluid dynamics and applied basic research" have interpreted the fundamental cornerstone of basic research in the development of the industry by using easy to understand words and vivid slides.

　 Four key breakthroughs

Independently develop new nozzle

Moderator: after 16 years of intensive research, your research team has made great progress in this research. What are the implications for achieving efficient textiles?

Yu Chongwen: this project has carried out a comprehensive and comprehensive original basic research on the dynamics of two phase flow in the high-speed airflow field. It has revealed the flexible fiber / high-speed airstream two phase hydrodynamic characteristics. It not only has important academic value, but also has obtained the processing characteristics of jet spinning (Wo Liu) spinning, airflow nozzle reducing yarn hairiness and melt blowing through the engineering application of theoretical research results in textile field. It provides a theoretical reference for the development of textile technology and equipment involved in fiber / high-speed airflow two-phase flow and coupling.

The results of the project are in line with the requirements of the national implementation of the basic theory and cutting-edge technology research in the key areas such as basic research, strengthening spinning, weaving and processing, and providing the theoretical guidance and source power for the industry's independent innovation.

Moderator: what is the result of this theoretical research applied to the practice of textile engineering?

Ceng Yongchun: in the process of applying this research to practice, the project team designed and developed the free end air-jet spinning nozzles with independent intellectual property rights and gradually improved the system parameters of the process parameters. By the Shanghai Textile Machinery Research Institute of Pacific Electric and mechanical group, the key components of the domestic air jet spinning machine, the nozzle, were developed, providing the core technology for the localization of advanced equipment. The key components of the melted nonwovens were designed with the cooperation of Shandong Yantai Huada Technology Co., Ltd., and the numerical simulation method was used to guide the experimental research. Based on this, a medium and large scale melt blown non-woven production line was developed and has been put on the market.

Moderator: from a technical point of view, textile fiber to achieve high-speed air flow need to carry out what technical research?

Yu Chongwen: first of all, we have constructed the "Pearl rod" chain fiber model and the fiber model based on the finite element method, which can reasonably reflect the fiber's large aspect ratio, flexibility and elasticity. The fiber model can describe not only the location and orientation of fibers, but also the deformation of fibers such as bending, torsion and stretching.

Second, right. Do spinning The characteristics of high-speed gas flow field in nozzle (including jet spinning, jet vortex spinning and airflow reducing nozzle) have been deeply and systematically studied. Numerical simulation and experimental testing techniques have been used to study theoretically and experimentally the characteristics of high-speed airflow field, including the development and evolution of swirling jet, reflux and vortex breakage in time and space, and the effect of important parameters on the swirling flow characteristics.

Thirdly, the Lagrange and Euler method is used to construct the unidirectional and bidirectional coupling dynamic model of fiber / airstream two-phase flow, and the numerical simulation of the movement of the fiber in the swirling airflow field of the spinning nozzle is realized. The high-speed camera technology is used to carry out experimental research, and the motion and deformation characteristics of the fiber dimension and its interaction with the high-speed airflow field are obtained.

Finally, the theoretical research results are applied to engineering. According to the numerical simulation results of the interaction between fiber and high speed airflow and the laws of fiber movement and deformation, the motion rules of the new textile technology based on high speed airflow, such as air-jet spinning, air-jet vortex spinning and airflow reducing hairiness, are analyzed, the technological principle is revealed, the technological parameters are optimized, the structural parameters of the nozzle are designed, the yarn quality is predicted, and a reasonable selection of fiber performance parameters is provided. A nozzle device with independent property rights is designed and developed.

　　 From laboratory to workshop

Advantage of basic science

Moderator: as a basic textile science project, where are its main technological innovations embodied?

Ceng Yongchun: it is mainly embodied in five aspects: first, a fiber model based on flexibility is constructed. The "Pearl bar" chain and the fiber model based on the finite element method incorporate the soft elastic physical characteristics of the fiber into a reasonable description of the location, orientation and deformation of the fiber in high-speed airflow.

The two is to reveal the characteristics of coupling and movement and deformation of fibers in high-speed airflow. We use Lagrange Euler method to construct the coupling dynamics model of fiber / airflow. For the first time in the world, we have realized the numerical simulation of the movement of fibers in the nozzle of jet spinning, jet vortex spinning and airflow attenuation.

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The three is the numerical simulation and experimental test of the flow characteristics of the high speed airflow in the spinning nozzles. In the first place, the technology of computational fluid dynamics (CFD) and laser Doppler velocimetry (LDV) were used to simulate the characteristics of high-speed airflow field, including the distribution of velocity and pressure, the development of swirling jet, reflux and vortex breakage, which provided an effective method for studying the characteristics of airflow in the nozzle.

The four is the application of fiber / high-speed airflow two phase fluid dynamics theory in high speed rotor spinning. The mechanism of twisting and air-jet nozzles to reduce yarn hairiness is revealed, and a spinning nozzle with independent intellectual property is designed. The system optimization and precise prediction of yarn quality are realized.

Five, the fiber / high-speed airstream two-phase fluid dynamics model is extended to microfiber spinning and stretching technology. Based on the theoretical results of fiber / high-speed airstream two-phase fluid dynamics, the stretching process of polymer fibers in high velocity airflow field was simulated, and the three-dimensional trajectories of fiber movement were obtained. The diameter, stress and whipping amplitude of fibers were predicted, which provided an effective research tool for microfiber forming mechanism.

Moderator: what are the benefits of "fiber / high-speed airflow two phase hydrodynamics" to the practical application of an enterprise?

Yu Chongwen: in 2003, on the development of the domestic air-jet spinning machine, the project team worked with the Shanghai Pacific Electromechanical group to calculate and analyze the nozzle flow field and fiber movement theoretically, and designed the nozzle of the key component of the jet spinning. The air-jet yarn produced by the nozzle is of excellent quality. The Shanghai Pacific Electromechanical group has developed the jet spinning machine with independent intellectual property rights by using the nozzle, and has been well received at the Shanghai International Textile Machinery Exhibition.

In 2007, the project team worked with the Hunan Huasheng Group Zhuzhou cedar hemp industry company to develop high-grade ramie fabric. The airliner developed by the project team to reduce ramie hairiness was used to reduce the hairiness of ramie and its blended yarns. The length of wool could be reduced by more than 50%. It not only improved the weaving efficiency of ramie yarn, but also effectively improved the prickle sensation of ramie fabric, and played an important role in developing high and thin ramie fabrics and knitted products, resulting in significant economic and social benefits.

In 2009, we worked with Shandong Yantai Huada Technology Co., Ltd. to design the key components of melt blown nonwovens equipment. The numerical simulation method was used to guide the experimental research, and the velocity and temperature distribution of the high velocity and high temperature airflow field were obtained. It was used to guide the experimental research, reduced the blindness of the experimental research, and greatly saved the time and material cost of the experiment. Non-woven fabrics The production line has been put on the market.