Simulation On The Flow Field Of A Dual Slot Die In The Melt-blown Process

Among the melt blowing devices, dual slots are widely used. Two strands of air which has high speed and high temperature eject and converge from the air clefts on both side of the slot die and they stretch the polymer melt squeezed from the melt slot. If you know the rule of the air temperature and velocity in the flow field, simulation on how the fiber is formed can be done and the quality of the fibers can be predicted. So that we can optimize the melt blowing process and improve the quality of products and save cost.An air-jet flow field model of the dual slot die in the melt blowing process was established on the basis of the model which is established by Chen Ting in 2005.Reynolds stress model was chosen as the turbulence model. The governing equations of this model were confirmed and they were discretized by Simple Algorithm.The computational domain was ensured and divided into grids. The velocity distribution and temperature distribution of the flow field along the direction of slot axis was got through numerical simulation. It was found that the velocity of x direction and the air temperature increases when the angle between air passage and slot axis grow smaller or the width of air passage becomes wider or the width of the dual slot die gets narrower."Ball-Spring" fiber model was chosen to make the simulation of the fibers' movement condition in the flow field. By analyzing the graphs of velocity vectors we knew that the tilt angle grew larger while the fiber was moving and the distance between the fiber and the spinning line increased while the initial flow rate increased and the tilt angle became smaller if it was nearer to the die.