| Due to the advantages of high efficiency,wide range and strong variety adaptability,air-jet loom is the most promising shuttleless loom.The air-jet weft insertion system is mainly composed of main nozzle,multiple groups of auxiliary nozzles and special-shaped reed.Using multiple nozzles to relay weft insertion will consume a lot of air,and the weft yarn will be deformed by the friction of the synthetic flow field of multiple nozzle jets.It can be seen that the synthetic flow field characteristics of the main and auxiliary nozzle jet directly affect the weft insertion speed,energy consumption and the final quality of the fabric of the air-jet loom.Therefore,taking the air-jet weft insertion system as the object,this subject aims to study the characteristics of weft insertion synthetic flow field and the dynamic behavior of air weft yarn two-phase coupling by using theoretical analysis,numerical simulation and experimental methods,and reveal the sensitive factors affecting the synthetic air flow characteristics and weft yarn motion law in the special-shaped reed.The following research progress has been made:（1）Based on computational fluid dynamics（CFD）and experimental method,the synthetic flow field of three different auxiliary nozzle jets with single circular hole,regular triangular hole and star hole into the special-shaped reed is numerically simulated by using Reynolds time average equation.A comprehensive experimental system of weft insertion synthetic flow field is designed to verify the correctness of the numerical results,and the inlet air supply pressure,outlet shape The results show that when the auxiliary nozzle is a star hole,the average velocity of the synthetic gas flow along the central axis is the highest.（2）Based on the elastic theory,the constitutive equation of flexible yarn is constructed,and the dynamic model of air flow weft single-phase coupling is established.The motion stability of yarn in the special-shaped reed groove is obtained by numerical simulation.The effects of the outlet shape and size of auxiliary nozzle and air supply pressure on the end wave motion of flexible weft yarn are discussed.The results show that when the auxiliary nozzle is a star hole,the motion stability of weft yarn is the best.（3）Numerical simulation of air flow weft two-phase coupling in special-shaped reed slot and weft motion experiment of high-speed photography,the control equation of air flow weft two-phase coupling is established by Lagrange Euler method,and the motion stability of yarn in special-shaped reed slot is obtained.The correctness of the simulation results is verified by the images captured by high-speed photography system.The results show that when the auxiliary nozzle is a star hole,the weft insertion stability is the best.The subject makes an in-depth study on the dynamic process of air-jet weft insertion,and discusses in detail the effects of the air supply pressure,geometry and size of the auxiliary nozzle on the synthetic flow field distribution and weft motion stability in the special-shaped reed.The results show that the auxiliary nozzle is a star hole,the distance between the auxiliary nozzles is 70 mm,and the air supply pressure is 0.4MPa.When the size is large,the weft insertion speed is high and the weft motion stability is the best.The research results of this subject can provide theoretical guidance for optimizing the design of auxiliary nozzle to solve the problems of weft break and large gas consumption,shorten the research cycle,and have important economic value.The research results of this subject provide theoretical guidance for optimizing the design of auxiliary nozzle,solving the problems of weft break and large gas consumption,and shorten the research cycle,which has important economic value. |
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