Research On The Analysis And Optimization Of The Airflow Field Of The Main Nozzle In An Air-Jet Loom Based On CFD

In this paper, simulation of the insertion flow field of the main nozzle with ZAX type in an air-jet loom is carried out based on Fluent. It is observed that there exists obvious backflow phenomenon and strong turbulence area under high air supply pressure in this main nozzle. Therefore, a new main nozzle composed of two nozzle needles connected in series is designed, and the insertion flow field of the new main nozzle is also simulated by use of Fluent. In order to verify the simulation of the two nozzles described above, two kinds of nozzles are made by 3D rapid prototype technology.When the simulation of the insertion airflow field of the two nozzles is compared with each other, it is observed that:1) When the air supply pressure is more than 0.3 MPa, there exists backflow phenomenon in the upstream area both in the commonly-used main nozzle and the new main nozzle. However, when the air is distributed reasonably, the turbulence strength can be effectively controlled under different air supply pressures, and the backflow phenomenon generated under high air supply pressures can be eliminated. Therefore, when the air is distributed reasonably, a preferred airflow performance can be obtained.2) In this new main nozzle, because the internal flow passage of the needle in upstream area works as an acceleration area, and it plays an important role in the internal airflow performance. Thus, the air supply pressure of the inlet in the upstream area compared with that of the other inlet is much higher, the internal airflow plays much better when the air supply pressure of inlet in the upstream area is less than 0.4 MPa. However, the strong turbulence area generated by high air supply pressure may also influence the airflow performance at the downstream area.3) Though there exists the backflow phenomenon at the upstream area, a better airflow performance may also be obtained when the backflow is too weak to influence the airflow performance.4) The length of the core area of the external airflow field of the new main nozzle is longer than that of the commonly-used nozzle. Thus, it is good for the actual production.5) When comparing the air drag force of the internal and weft insertion flow field of the two main nozzles with each other, it is observed that air drag force of the new main nozzle can be improved with a preferred air distribution, and the air drag force of the internal flow field is in a high proportion of the air drag force of the weft insertion flow field.6) As air supply pressure increases, air consumption of the new main nozzle can be effectively controlled when compared with that of the commonly-used nozzle.After experiment, it is observed that the velocity of the centerline of the external airflow of the two nozzles is in good agreement with that of the simulation. Therefore, the simulation is validated perfectly.