The Analysis Of Gas Flow And Optimization Of The Structure Of Single Hole Auxiliary Nozzle In Air-Jet Looms

In order to improve the utilization of auxiliary nozzle jet and prevent the quickly spread of the weft insertion jet, this thesis independently designed and produced more efficient nozzle based on the current auxiliary nozzle structure.Then this thesis adopted CFD to construct the weft insertion channel combination model of the reed and auxiliary nozzle and using theoretical, experimental methods and verification to research this task. Through the theory of CFD, the flow field for weft insertion were analysized, the expansion wave of the auxiliary nozzle jet and the auxiliary high-speed jet spraying process solved by CFD were explained; the airflow basic control equation were established; weft insertion channel airflow turbulence model was set.The gas flow distribution of a single auxiliary nozzle was numerically simulated at first. The effects of some factors, such as the size and shape of the sectional area at the exit of auxiliary nozzle, to the gas flow field were analyzed. The results show that the velocity of jet increasing with the pore size rising; when the pore size is 1.1 mm, the jet strength is not enough; when the pore size is 1.5 mm2, the jet concentration strength is bring down; the pore size of nozzle is 1.3mm, jet concentration was better and the gas flow is lower than the 1.5mm pore size; A certain taper angle is also helpful for saving enery,it is beneficial to enhancing the jet pressure and velocity, and the effect of the optimal is 20°; change the circular orifice to D, when D form the nozzle cross section area is 1.54 mm2, weft insertion works best.Beside, in order to examine the rationality of the numerical simulation, this paper put the theoretical research results into practical application. The performance of the optimized auxiliary nozzle was tested through experiment and jet velocity and the curves of weft tension were obtained. Then the numerical simulation was verified by the experiment. Therefore, it proved that it was feasibility and rationality of the numerical simulation on flow field of auxiliary nozzle for weft insertion by Fluent.The gas flow distribution of two auxiliary nozzles was numerically simulated either.and the effect of auxiliary nozzle structure parameters on concurrent flow was analysized.The effects of pore size, hole shape and spaces between two sub-nozzles etc to the gas flow field were analyzed. The results show that the space between two sub-nozzles has the greatest influence to the complex gas flow field. When the pore size is 1.3 mm, the best space is 60mm. If the space increase, we should send up the gas supply pressure to guarantee the efficiency of weft insertion.In conclusion, in this article, through the combined method of theoretical and experimental research, the auxiliary nozzle in the weft insertion motion law and characteristics of the high speed air flow field in the channel are studied, and the improvement of air-jet loom weft insertion system, reduce energy consumption of air weft insertion has certain theoretical significance and practical value.