Numerical Simulation On High Speed Air Flow In Air-jet Weaying Machines By Using CFD

In modern weaving industry，due to their high productivity, low-noise level and high versatility,more and more air-jet weaving machines are used to weave many kinds of fabrics, includingsome technical textiles. The common pneumatic weft insertion system comprises a main nozzle,several groups of relay nozzles and a profiled reed channel. The weft yarn obtains its initialvelocity from the air flow in the main nozzle. After that, it flies through the reed channel with thehelp of jets from relay nozzles. These nozzles consume much compressed air, so the energyconsumption of air-jet loom is higher. And there is no much guidance to the parameter settingsand arrangement of insertion system. It is important to study these problems for energy savingand improvement on insertion quality.The CFD method was applied to simulate air flow fields in air-jet looms. Firstly, a numericalmodel for the relay nozzle was constructed, and the jet flow fields were obtained with differentinlet pressures. Then, the flow fields in the profiled reed channel were calculated. There weretwo kinds of such models, one simple model without reeds and one complex model with reeds.The results show that the realizable k εturbulence model is suitable to compute jet flowfrom relay nozzle; the channel model with reeds can obtain better prediction of the flow field；490kPa pressure is suitable for weft insertion;65mm distance between relay nozzles is good forhigh speed and steady air flow; air speeds in different zones are rather different in reed channel;the nozzle with single tapered hole is more efficient compared with that with single cylindricalhole.