| In this thesis, the development on the design and simulation of air jet in the attenuator of the spunbonding system has been briefly reviewed, and then the air jet in Nordson's MicroFil? Spunbond System with a slot attenuator was simulated and tested, and the structure of the attenuator was optimized as well. The details are as follows:Firstly, the formulas of the flow velocity, pressure, energy, momentum, impacting force of the plane air jet were built, taking into account the factors of the main flow Mv, nozzle flow and efficiency indexη, the velocity correction factor Kv. Thus a more perfect formula of the air jet converged by two parts of air jet was established and the the velocity of the air jet in the actual spunbonding process was calculated.Secondly, the realizable k-εmodel was selected to simulate the above swirling air jet converged from two tapered channels, separating and coupling calculator were used to calculate the two-dimensional and three-dimensional models, and the QUICK format was chosed to discrete the simulation model and the controlling equation. Combined with the boundary conditions, numerical simulation was achieved.Thirdly, the air pressure-velocity conversion rate, the initial velocity distribution, the radial pressure distribution, turbulence intensity and distribution of turbulent dissipation rate were simulated at different working conditions and different structural parameters of the slot attenuator, and the optimized structure of the slot attenuator was gained as well.Finally, the simulated pressure and velocity of the air jet were introduced into the drawing model of polymer fibers to test the simulation results. It showed that the fineness and crystallinity of the actual fibers and the corresponding simulated values are very similar, which means that the simulation results are correct.
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