Numerical Simulation Of Pneumatic Conveying Movement Behavior Based On Molding Sand In Lost Foam Casting

Pneumatic conveying is one kind of delivery method that carries the solid particles in the pipe from one place to another by use of gas as the medium. As there is no return stroke in the pneumatic conveying, the solid particles in the pipe completely isolated from the external environment, so it will not pollute the environment. And the equipment is relatively simple, is an environmental-friendly delivery method. Therefore, more and more attention by all walks of life was paid on the pneumatic conveying industries pay more attention, which has a broad application prospect.In this paper, the flow characteristics of the large particle size, high density of molding sand granule in vertical riser pipe and horizontal pipe was simulated through numerical simulation method. In t he process of FLUENT simulation, the gas phase used the k-ε standard equation model. The molding sand was taken as quasi-fluid, and the euler-euler two fluid mathematical physical models which based on the particle dynamics for pneumatic conveying was buil t up.Based on FLUENT software platform, using the established euler-euler two fluid mathematical physical model which based on the particle dynamics, according to the known conveyor requirements and process parameters, and combined with the other conveyor in practical application conditions, for different operating mode, simulation of vertical riser pipe and horizontal conveying pipe of pneumatic conveying under these conditions respectively. Through the simulation, the velocity distribution, concentration distribution and pressure drop of the gas-solid two phase was obtained. The simulation results of the vertical riser pipe reveal that, gas-solid two-phase exists acceleration phase and constant rate period in the vertical riser pipe when the air speed stays constant; gas-solid two-phase exists acceleration phase and constant rate period in the vertical riser pipe even when the air convey in different speeds. And with the increase of the air conveyor speed, the residence time of solid particles in vertical riser pipe is smaller; the speed of solids conveyor is higher. Then the static pressure and static pressure drop in the vertical riser pipe increase with the increase of granule density.The simulation results of the horizontal conveying pipe reveal that: as the same with the vertical riser pipe, the pneumatic conveying process in the horizontal conveying pipe also can be divided into acceleration stage and constant period; when the air conveying speed and solid particles density remain the same, the concentration of solid particles present high in the center of the pipe, low in the pipe wall in the horizontal direction; and present “I” type distribution in the vertical direction. When the transport capacity stay constant, there always exist a saltation velocity with the change of air conveying speed; when the air conveying speed stay the same, the saltation velocity and pressure drop increased with the increase of the transport capacity. Compared the pneumatic conveying process in the vertical riser pipe with the horizontal conveying pipe, found that the pressure and saltation velocity in the horizontal pipe is smaller than vertical pipe. When the other parameters all stay constant, the pressure drop decreased with the increase of the solid particles density; the saltation velocity decreases first and then increases with the increase of the solid particles density, means that corresponding to the lowest energy consumption exist an optimal density.Through the research of the flow characteristic of gas-solid two phase in different pipe, accurate control the flow in the interior of the pipe, can decrease the effects that various factors during the transport process in the pipe, enhance the transport efficiency and factory operating has a certain guiding significance.