Study On Parameter Optimization Of The Circumferentially Arranged Air Nozzle Group

In recent years,the preparation and properties of nanofibers have become the research objects of many researchers.The centrifugal spinning method has attracted much attention because of its simple equipment,no high pressure,no pollution and high output.The principle of centrifugal spinning is that polymer solution or melt is extruded from spinneret hole and stretched into fiber under the action of centrifugal force in the high-speed rotating device.It is a kind of preparation method for microfibers and nanofibers with industrial application prospect.Based on the theory of melt blowing,our research group has put forward the air assisted centrifugal spinning method.In addition to the centrifugal force,air force was added to the polymer filaments to further draw the fibers.In this paper,the theoretical modeling and numerical simulation of the air flow field of the circumferential arranged air nozzle group for the air assisted centrifugal spinning are carried out,and the simulation results are verified by experiments.The orthogonal regression and genetic algorithm-support vector machine method are used to optimize the parameters of the nozzle group.This paper mainly includes the following contents:(1)The air flow field model of the circumferential arranged circular nozzle group is established,and the numerical simulation of air flow field is carried out.The influence of the rotating speed on air velocity distribution is explored.It is found that the increase of the rotating speed has a great impact on air velocity distribution.An IFA300 hot wire anemometer is used to measure the velocity of air flow field of the circumferential arranged circular nozzle group.The simulation results are in good agreement with the measurement results,which proves that it is feasible to use the computational fluid dynamics method to study the air flow field of the air assisted centrifugal spinning.(2)The air flow field model of the circumferential arranged annular nozzle group is established,and the air flow field is simulated.The simulation results show that the nozzle angle and nozzle ring width are important factors affecting the air velocity distribution except the rotating speed.The inlet velocity,rotating speed,nozzle angle and nozzle ring width of the nozzle group are optimized by the quadratic orthogonal regression design,and the relevant optimal parameters are obtained.The inlet speed is 118 m/s,the rotation speed is 1140 r/min,the nozzle ring width is 0.8 mm,and the nozzle angle is 69°.(3)Based on the air flow field model of the circumferential arranged annular nozzle group,the air velocity of the circumferential arranged annular nozzle group is predicted by using the genetic algorithm-support vector machine method.Compared with the prediction results of the ridge regression method,the superiority of genetic algorithm-support vector machine method is proved.Genetic algorithm-support vector machine is used to optimize the inlet velocity,rotating speed,nozzle angle and nozzle ring width of the nozzle group,the inlet speed is 115 m/s,the rotation speed is 440 r/min,the nozzle ring width is 1 mm,and the nozzle angle is 62°.The air flow field with the optimal parameters is improved compared with the air flow field optimized by the orthogonal regression,the average velocity is higher and the dissipation rate of velocity is lower.To sum up,in this paper the air flow field model of the circumferential arranged nozzle group is established.The air flow field is simulated and measured.The parameters of the circumferential arranged nozzle group for the air assisted centrifugal spinning are optimized using the genetic algorithm-support vector machine method,which lays the foundation for the parameter optimization of the air assisted centrifugal spinning method.