熔喷过程中纤维直径再次变大的模拟与验证

为直观表达熔喷过程中气流对纤维的拉伸作用,对熔喷过程中的纤维运动进行了数值模拟。首先将熔喷过程中的纤维看作是由麦克斯韦(Maxwell)元件连接的珠子;之后将已知的纤维速度、纤维温度数据加载到纤维模型上,通过拉格朗日法数值模拟预测纤维在熔喷过程中的运动速度、纤维直径等信息。模拟结果表明,纤维在远离喷丝孔的过程中,由于气流速度、气流温度逐渐衰减,致使纤维受到气流力的作用逐渐减弱,若气流力小于纤维自身的黏弹力,纤维会在黏弹力的作用下回缩,在宏观上表现为纤维直径的再次增大。最后在一定实验条件下,利用线下方法测量了熔喷纤维的直径,实验结果也验证了熔喷过程中纤维直径会有再次变大的现象。

Simulation and verification of fiber diameter re-increasing in melt blowing process

In order to directly express the attenuation effect of the air on the fiber in the melt blowing process,the fiber motion in the melt blowing was numerically simulated.Firstly,the fiber in the melt blowing was regarded as beads which connected by Maxwell elements.Then,given air velocity and air temperature were applied to the fiber model.The information such as fiber velocity and fiber diameter in the melt blowing was predicted by this simulation via Lagrange method.The simulation results showed that in the process that the fiber is far away from the spinneret,the air flow force applied on the fiber gradually weakened as the air velocity and air temperature gradually decreased.The fiber retracts under viscoelastic force when the air flow force was less than the viscoelastic force of the fiber,which macroscopically shows the fiber diameter re-increasing.Finally,the fiber diameters were off-line measured under certain experimental conditions,and the result also indicates the fiber diameter reincreasing phenomenon in melt blowing process.