| Air-jet loom is a high-tech product equipped with optics, mechatronics, and pneumatics. With its expansion of adaptability for fabric varieties and the improvement of breadth, weft insertion rate, running efficiency, automation and intelligent level, air-jet loom has become the most important weaving equipment which has the increasing demand and the, wide marketing prospects in the weaving industry.On the air-jet loom, the weft is carried through the shed by the jetted air which is of flowing-bunching characteristics. At present, owing to lack of the systematic theoretical analysis and experiment, it's hard to come to the ideal application for the operating efficiency, reliability, and energy consumption etc. Therefore, we should continue to research the weft insertion field deeply on the air-jet loom.This thesis has analyzed the working principle of air-jet inserting and the basic fluid dynamics theory involved in weft-insertion flow field. Based on principles of fluid dynamics, the numerical models about the weft flow fields of the primary nozzle and secondary nozzles in air-jet loom were established, and the flow field characteristics of airflow jetting in the primary and secondary nozzles were analyzed and simulated with FLUENT 6.3. The simulation results were analyzed.The simulation for main nozzle shows that the ideal air in equivalent temperature came to a steady flow when entered into cone-shaped section, and the flow velocity reached the maximum at laryngeal part of the inner channel, while the flow pressure reached the minimum. The results visually demonstrated the flow field of the inner channel of main-nozzle, and it could provide reference for optimizing parameter on main-nozzle of air-jet loom.Meanwhile, the simulation for auxiliary nozzle revealed that the gas velocity increased with the auxiliary nozzle pipe inner-sectional area decreases; and the ejecting capacity of four orifice-form auxiliary nozzle supplied with the same air-pressure took turns: 7 circular orifices > rectangular orifice > circular twin-orifice > single circular orifice. At the same time, the results of simulation could provide reference for optimizing parameter on assistant nozzle of air-jet loom.A test-bed for weft-insertion flow field of air-jet loom is developed, and a experiment plan as "Characteristics of airflow under the action of auxiliary nozzle" is designed. Based on the test on the time-displacement curves of flying weft—T (S), it derived the relationship between auxiliary nozzle's air-jet effects and its angle, distance of auxiliary nozzle or air pressure. Then techniques parameter could be obtained such as optimal weft insertion time and the least air consumption.The experiment revealed that the more measuring points near the channel side, the lower flow rate would be on the same channel's transect, because the airflow diffused to opening side of the flow channel. If the measuring points near the channel's inner side and the high position, its flow rate was highest, so it indicates that airflow leaned to the inner side. In addition, if a jet-angle is given, the greater the gas pressure would lead to greater flow rate; the smaller distance between auxiliary nozzles would lead to the higher average airflow rate. In a word, air flow speed was associated with jet-angle, distance between auxiliary nozzle and air pressure. Therefore, the jet-angle, distance between auxiliary nozzle and air pressure should be taken into account when we choose technical parameter.Through this combination of numerical simulation and experiment, we hoped it could provide some new ideas and practical means for study air-jet loom weft insertion flow, and would be helpful for improving air-jet looms' weft insertion quality.
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