Prelimiary Study On The Air Flow Field Of The Air Centrifugal Spinning

A new process, namely, centrifugal spinning has been developed to producesubmicron fibers. This new method uses the centrifugal force produced by the high-speedrotation of a spinneret to make submicron fibers from polymer melt or solution. So, thevelocity distribution of the air flow field has an important effect on the fiber diameter.Improvement of the spinneret will influence the velocity distribution of the air flow field.In this thesis, an annular nozzle is installed around the spinneret, that is, add an air force tothe centrifugal force. The centrifugal force and air force draw the polymer together tofurther decrease the fiber diameter. The air flow field of the air centrifugal spinning isestablished and simulated numerically, which lays a foundation for modeling the polymerdrawing. This thesis can be divided into four parts:In Part one, the air flow fields of round nozzles and annular nozzles around rotatingspinnerets are modeled. Computation meshes are divided and boundary conditions are set.The models consist of the continuity equation, momentum equation, turbulent equation andboundary conditions.In Part two, the air flow fields of round nozzles and annular nozzles around rotatingspinnerets are simulated numerically. Distributions of air velocity, pressure andtemperature have been obtained, respectively. Then the simulation results are analyzed.In Part three, an IFA300hot wire anemometer is employed to measure the velocitydistribution of the air flow field of round nozzles around rotating spinnerets. The simulatedresults are compared with the measured results. Results show that the simulated resultshave a good agreement with the measured results, which proves that the established modelis effective.In the last part, effects of the rotating speed on the velocity distribution of the airflow field of round nozzles are simulated and measured. It is found that the velocitydistribution curves of different rotating speeds almost overlap within the distance about50 mm away from the nozzle, which indicates that the rotating speed has insignificant effecton the velocity distribution within this distance. The simulated results of different speedstally with the measured results, which proves that the correctness of the established model.To sum up, the air flow field model of the air centrifugal spinning is established,simulated and verified, which lays a foundation for establishment and solving of thepolymer drawing model of the air centrifugal spinning.Second, this paper simulates the air flow field theoretical model of dual die in centrifugalspinning process with an auxiliary nozzle. In the end, the distribution of air velocity,pressure and temperature have been obtained respectively, then analyze elaborated to theresult.