Study On The Air Flow Field Of The Air Supply Duct In The Spunbonding Process

In spunbonding process,the polymer stream is rapidly cooled by the cooling air when it is extruded from the spinneret. So the cooling effect has a great influence on the appearance quality, fiber fineness and uniformity of spunbonded nonwoven fabrics. The air supply duct is the necessary air channel before touching the polymer melt. The air flow field in the air supply duct determines how the cooling air exchanges energy with the polymer melt and thus influences the cooling effect. Adjusting the structure of the air supply duct to change the air flow field and thus improving the cooling effect is an important approach to improving the quality of nonwoven fabrics. Adding a blast fence is a beneficial attempt to change the air flow field of the air supply duct.In this thesis, the air flow field of the air supplying duct in the spunbonding process is modeled and simulated numerically. And the related parameters of the blast fences are designed optimally.This thesis consists of the following three parts.In the first part, the mathematical model of the air flow field of air supplying duct in spunbonding process is etablished. The air flow field model consists of the continuity equation, momentum equation, turbulence equation and boundary conditions. The RNG k-ε model is the preferred turbulence model. The equations of the air flow field model are discretized using the finite volume method.In the second part, the air flow field model of the air supply duct in the spunbonding process is simulated numerically. The Pitot tube is utilized to measure the velocity distribution of the air flow field of the air supply duct. The simulation results are compared with the measured results and they shows good agreement with each other, which confirms the effectiveness of the air flow field model.In the third part, based on the air flow field model of air supplying duct in spunbonding process, the optimization design for the baffle parameters of air supplying duct is carried out using the method of quadratic orthogonal rotational combination design with three factors. The baffle parameters include the baffle length, baffle incline and radius of the arc baffle. The optimal parameters are obtained.To sum up, in this thesis, the air flow field model of the air supplying duct in the spunbonding process is established. Then the air flow field model is simulated numerically and verified experimentally. On the base of the air flow field model, the baffle parameters of air supplying duct are designed optimally, which lays a foundation for further researches on the air flow field of the air supplying duct and improvement of the air supply duct.