Numerical And Experimental Analysis Of Weft Insertion Flow Field And Structural Optimization Of Main Nozzle In An Air-Jet Loom

Main nozzle and auxiliary nozzle are the key parts of the weft insertionmechanism. Jet performance of the nozzles has a significant influence in weavingefficiency and textile quality. The research of main nozzle is focused on the flow fieldsimulation and experiment test, in contrast, there is little structural optimization ofmain nozzle and numerical simulation of weft insertion flow field, which is composedof main and auxiliary nozzle, profiled reed and shedding triangle.The flow field characteristic of type ZAX main nozzle is explained based onnumerical simulation. In order to verify the correctness of numerical simulation, anairflow test platform is established, so that the airflow pressure and velocity of the weftinsertion flow field are measured by means of pitot tube and differential pressuretransmitter. The comparison and analysis between numerical simulation and tested datashow that the method is correct and feasible.Then the computational formula of weft drag force is obtained by theory of onedimensional steady adiabatic pipe flow and equation of gas state. Then weft drag forceunder different types of air supply pressure is computed by numerical integration,which is an important measurement criterion of jet performance of the main nozzle.Afterwards number of rectifier tank, external diameter of needle tip, distance betweenneedle tip and rectifier tank, α face projected length and diameter of acceleration tubeare optimized with combination of numerical simulation and orthogonal test.At the same time the combination of flow field of main nozzle and auxiliarynozzle is researched through numerical simulation. Results indicate that auxiliarynozzle jet has no influence on main nozzle jet and the axis velocity of which isinvariant. Whereas there is an impact at junction position of above two jets, so the axisvelocity is decreased with small fluctuation of local static pressure and jet center will be situated at inner side of profiled reed. As result of supplement from auxiliary nozzlejet, steady weft insertion flow field is produced and airflow velocity attenuationbecome slowly.Based on above research, air supply pressure and installed angle of auxiliarynozzle and distance from main nozzle to the first auxiliary nozzle are optimized.Because the main nozzle is near the first auxiliary nozzle, air supply pressure anddistance between main nozzle and the first auxiliary nozzle has a great influence onflow field, but installed angle of auxiliary nozzle is in opposite. With increase of airsupply pressure, the center velocity of flow field becomes larger, but energyconsumption is also increased.With the method of numerical simulation and experiment test, a series of mainnozzle matched different air supply pressure is obtained and parameters of weftinsertion process are optimized, so that the work of this paper can be benefit for designof main nozzle and decrease of energy consumption.