Study On The Air Flow Field Of Circumferential Arranged Oblique Nozzle Grouping

In recent years, the centrifugal spinning, as a new technology to produce micro-nano fibers, gradually attracts the attention of researchers. This new method uses the centrifugal force produced by the high-speed rotating device to make micro-nano fibers from polymer melts or solutions. In order to further reduce the fiber diameter, annular air nozzles are added around the spinnerets, so called air centrifugal spinning. In this way, the polymer is drawn by both the centrifugal force and the air force. Therefore, the air flow field of the air centrifugal spinning has an important influence on the fiber diameter. In this thesis, oblique air nozzles are installed around the spinnerets of the centrifugal spinning equipment, the air flow field of the circumferential arranged oblique air nozzle grouping is modeled and simulated numerically, and the related parameters are designed optimally. This research consists of the following four parts:In the first part, the air flow field of circumferential arranged round oblique nozzle grouping is modeled. After computation meshes are divided and boundary conditions are set, the numerical simulation is done with the Fluent software. Distributions of the air velocity are obtained and analyzed.In the second part, an IFA300 hot wire anemometer is employed to measure the velocity distribution of the air flow field of circumferential arranged round oblique nozzle grouping around rotating spinnerets. In order to facilitate comparing the measured data with the simulation results, velocity distributions of the air flow fields with the rotational speed of 0 r/min, 320 r/min 560 r/min, 800 r/min, 1040 r/min are measured. The measured results are found in good agreement with the simulation results, which proves that the established model is effective.In the third part, the air flow field of circumferential arranged annular oblique nozzle grouping is modeled and simulated numerically. Distributions of air velocity is obtained and analyzed. Then the air flow field of annular oblique nozzle grouping is compared with that of annular horizontal nozzle grouping。 It is assumed that oblique nozzle is superior to the horizontal nozzle in terms of polymer drawing.In the last part, on the base of the air flow field model, the optimal design for the related parameters(nozzle number, rotational speed, initial air velocity and nozzle angle) is carried out. Experimental scheme is established using a quadratic general rotary unitized design method. The regression equation is established based on the simulation results. By using the constraint random direction search method, the optimal parameters are obtained.To sum up, the air flow field model of circumferential arranged oblique nozzle grouping is established and simulated. The related parameters are designed optimally. This research lays a foundation for further researches on the air flow field and polymer drawing model of the air centrifugal spinning.