Study On Weft Insertion System Of Air-jet Loom Based On Fluid-structure Coupling

The compressed air is used by weft insertion system of air-jet loom to inhale the weft yarn into the main nozzle.Then,the weft yarn is speeded up out of the guide tube.With the drag force of the main and auxiliary nozzles' compressed airflows,the weft yarn enters into the profiled dents groove steadily and quickly.Finally,the weft yarn completes the weft insertion movement through the shed.The paper studies the weft insertion system of air-jet loom.The method of numerical simulation and experimental research is adopted to study airflow field and fluid-structure coupling of the airflow and yarn with gaps.And the relationship of profiled dents' structure and the yarn movement,profiled dents' gap and the yarn movement are established.The paper reveals the flowing discipline of fluid-structure coupling,which will provide the theoretical basis on optimizing the weft insertion system including the problem of weft break,large gas consumption and so on.These tasks on the weft insertion system can be obtained as follows:(1)The numerical simulation of airflow field in profiled dents.The modeling method of irregular airflow channel is studied.Then airflow field characteristics are simulated,which include airflow velocity,mass flow rate,turbulence intensity and so on.The relationships of the angle ? of profiled dents and airflow characteristics,the gap of profiled dents and airflow characteristics are established.(2)The fluid-structure coupling of the airflow and yarn.The numerical simulation method of fluid-structure coupling is studied.The constitutive equation of the yarn and the equation of coupling of the fluid and yarn are established.Then yarn's movement characteristics are obtained in the profiled dents.The relationship of the gap of profiled dents and yarn's movement stability,the yarn's material and movement stability are established.(3)The experimental research of fluid-structure coupling in profiled dents groove.PIV technology is used to measure airflow field.The fluid velocity of different cross sections in profiled dents groove is obtained through the tracer particles.The high-speed camera is used to shoot the movement of yarn.And the yarn displacement and velocity are obtained.Comparisons of the experimental airflow field and yarn movement with the simulation results are obtained.Then the results validate that the simulation calculation is credible.And it provides a guideline for error analysis,result reasonability and the optimization of weft insertion system.