Numerical Simulation Study On The Process Of Electrospinning And Experimental Verification

Electrospinning is a new type of free-end spinning built on the electric field. According to Professor Darrell H. Reneker, electrospinning makes use of electric field force to produce nanofiber with diameter about 50nm. In the electrospinning process a high voltage is used to create an electrically charged jet of polymer solution or melt-Electric field is subjected to the end of a capillary tube that contains the polymer fluid held by its surface tension. This induces a charge on the surface of the liquid. Mutual charge repulsion causes a force directly opposite to the surface tension. As the intensity of the electric field is increased, the hemispherical surface of the fluid at the tip of the capillary tube elongates to form a conical shape known as the Taylor cone With increasing field, a critical value is attained when the repulsive electrostatic force overcomes the surface tension and a charged jet of fluid is ejected from the tip of the Taylor cone. The discharged polymer solution jet undergoes a whipping process wherein the solvent evaporates, leaving behind a charged polymer fiber, which lays itself randomly on a grounded collecting metal screen. Currently, electrospinning is a primary method to produce nanofiber. Producing quality nanofiber, the key is to ascertain the mechanism of electrospinning forming. The electrospinning jet is divided into three segment, the stable part and the unstable part,and there is zone between them is a transition zone. Each part has its own Forming mechanism, therefore firstly simulate each part separately and then do the entirety simulation. In this paper, the analysis on the influence of the formation of jet movement will come from the electric field, the flow field and force field. The CFD simulations are based on the analysis of the theory.As a branch of mechanics, fluid mechanics is widely applied in many areas. Polymer jet in the electrospinning belongs to fluid. Involving different aspects of fluid mechanics, the moving law of polymer jet is very complex. At the same time, there are some unknown parameters adding difficulties in analysis. So it is not desirable to use mathematical analysis to study the electrospinning jet. But the computatonal fluid dynamics (CFD) is desirable. Polyflow is CFD software dedicated to simulation of fluid base on finite element method. It contains the newest, perfect algorithm. In this paper. I will simulate the steady component of electrospinning jet in different conditions of electric field strength with Polyflow and make simulation results analysis, discussion and experiments. ANSYS FLUENT software contains the broad physical modeling capabilities needed to model flow, turbulence, heat transfer, and reactions for industrial applications ranging from air flow over an aircraft wing to combustion in a furnace, from bubble columns to oil platforms, from blood flow to semiconductor manufacturing, and from clean room design to wastewater treatment plants. Special models that give the software the ability to model in-cylinder combustion, aeroacoustics, turbomachinery. and multiphase systems have served to broaden its reach. In this paper, polyflow is used for the simulation of the stable part, and fluent for the others. After the simulation, High-speed Photography will take part in the analysis of comparing with the result of simulation.