Centrifugal Spinning Solution Flow Field And Optimal Design Of Nozzle Based On Grey Wolf Algorithm

High-speed centrifugal spinning is a novel method which uses the centrifugal force generated by high-speed rotation of the motor to keep the spinning solution jetting from the nozzle to form nanofibers.Compared with traditional techniques such as electrospinning and melt spinning,high-speed centrifugal spinning shows its advantages.Its structure is simple,which makes it easy to manufacture and operate,and it also can be used to produce a variety of spinning materials.What’s more,its energy consumption of manufacturing and production is low while its production efficiency is high,and it’s friendly to the environment,which has attracted more and more researcher’s attention.At present,researches on high-speed centrifugal spinning mainly involves fiber materials,properties,applications,parameter effects,jet trajectory and simulation experiments,while there are few researches on the optimization of spinning nozzles for the core components of spinning.Based on the introduction of high-speed centrifugal spinning principle and research background,this paper describes the research progress of high-speed centrifugal spinning and spinning nozzles as well as the principle and application of gray Wolf algorithm.Secondly,the flow state of spinning solution in the nozzle is analyzed,and the phenomenon that the existence of secondary-flow causes the deviation of the maximum velocity center of spinning solution is revealed.Then,the force of spinning solution was analyzed,and the flow velocity model of spinning solution in each region was established.Grey Wolf Algorithm was used to solve the model,to obtain the optimal solution of maximum velocity under the condition of minimum velocity deviation.Subsequently,the flow states of the solution in the straight-tube and the bent-tube nozzle were simulated to prove the existence of the secondary flow,and the factors affecting the velocity and velocity deviation were explored,and the solution flow velocity in the nozzle of the bent-tube was determined to concentrate at the center of the outlet section under the optimal parameters.Finally,the optimized bent-tube nozzle and unoptimized straight-tube nozzle were used for high-speed centrifugal spinning experiments.The experimental parameters were changed by using the control variable method,and the specific effects of each parameter on nanofibers were explored through fiber quality,morphology,and diameter distribution.The main research contents of this paper are described as follows:1.The properties and application fields of nanofibers as well as the characteristics and limitations of traditional preparation methods of nanofibers are briefly described.This paper describes the research purpose and significance of centrifugal spinning,expounds the research progress of spinning nozzles in centrifugal spinning and various spinning methods at home and abroad,and introduces the basic principle of GWA and its related applications.2.The principle of centrifugal spinning and the structure of centrifugal spinning nozzle are described.It is revealed that the maximum velocity region of spinning solution is offset by secondary flow generated by equipment rotation in the process of high-speed centrifugal spinning.This phenomenon is verified by the simulation results of the solution flow maximum velocity region in the non-rotating and rotating nozzle.3.Based on the mechanical analysis and kinetic energy theorem,the velocity expressions of spinning solution in the container,the shrink part,the straight tube,and the bent tube were derived.The relationship between the outlet velocity and the solution parameters,the nozzle parameters as well as the process parameters was established.The solution velocity offset model is established.The optimization parameters and the optimization function were determined,and the GWA was used to optimize the flow model of spinning solution with nozzle parameters,and the optimal solution of reaching the maximum outlet velocity under the condition of minimum velocity deviation was obtained.4.The existence of secondary flow is proved by the simulation of the straight-tube nozzle,and the influence of speed,outlet diameter and straight tube length on the velocity deviation is explored.Then,the flow state of the solution in the bent-tube nozzle was simulated under the optimal parameters with the solution velocity concentrated at the center of the bent-tube outlet,and the influence of the rotational speed,bent-tube angle,bent-tube radius and outlet diameter on the velocity and its deviation was explored.5.The optimized bent-tube nozzle and unoptimized straight-tube nozzle were used for high-speed centrifugal spinning experiments.The quality and diameter distribution of the fibers prepared by the two nozzles were compared under the optimal structural parameters.The experimental results showed that the fiber prepared by the bent-tube nozzle not only has better surface quality,but also the fiber diameter distribution is more distributed in the range of 400～1000nm than that of the straight tube.Then,the influence of solution concentration and rotation speed on the fiber is explored.Finally,the optimization of nozzle structure parameters by using GWA is summarized and analyzed,and the deficiencies in nozzle flow field simulation and PEO fiber production experiments are pointed out,and the follow-up research and improvement are put forward.