Studies On Bulk Solid Flow In Conical Hopper And Pneumatic Transport In Bend

The flow of granular materials and gas-solid two-phase flow in bend are studied in this dissertation. The stress, the strain and the strength in complex stress state of granular materials are investigated theoretically based on statics & kinematics of granular materials and continuum theory. The equations in the extreme stress state of granular materials are presented. The physical characteristic, the angle of internal friction, the angle of wall, friction and the angle of repose of granular material are measured and delved. Simultaneously, the flow pattern of granular material in a silo has been measured by using trace method. It is studied that the relationship between the angle of internal friction and shape & size of granular materials, the angle of wall friction and shape & size of granular materials, the angles of repose and shape & size of granular materials, the rate of granular materials flow and the diameter of the export, the rate of granular materials flow and the height of granular materials in a Perpex conical hopper. Subsequently an experimental method measuring relative velocity in conical hopper is set up. This method is used to check Jenike抯 Radial Stress theory and Principle of Co-axiality successfully, the experimental results show Jenike?s Radial Stress theory and Principle of Co-axiality aren抰 fit for all granular materials. Based on the analysis of the disperse system stress theory, it is researched that the influence of the angle of internal friction. The angle of wall. friction and the angles of repose of granular material of granular materials to the experimental results and the theory values of relative velocity of the granular materials in conical hopper and the direction of principal strain rate. The concept of relaxation is introduced when the non-equilibrium feature of gas-solid two-phase flow is investigated. The velocity relaxation and temperature relaxation of a particle and particle cloud in fluid are presented. The forces acting on a particle and particle cloud in flow field are analyzed. The drag coefficients of a particle and particle cloud in flow field are studied. The motions of spheric particle gravitation settling and in any flow field are researched. Using same flow velocity and isosection method performs an experimental study of cement-air two-phase flow in the bend. The results show that in the full separate stage of bend dense particle concentration in the vicinity of the ridge -line and relatively diluter well-distributed concentration in other region. Then ?III ? again in the primary stage of the bend the most part of the particles are violently separated from air flow by the centrifugal force and gathered towards the outside of the bend. The influence of the bend on the shape of particle concentration distribution still exists behind the vertical pipe. Using the fluid mechanics theory, the Gauss filtration governing equations are presented based on the incompressible Navier-Stokes equation in primitive variables, which are discretized using standard third-order accurate Galerkin finite element scheme in space and discretized using finite differencing scheme in time. A three-step finite element method and large eddy simulation are applied to turbulent flow at large Reynolds number with the Bi-CGSTAB numerical method. The numerical simulation is carried out at Reynolds number 400, which proved that the numerical model suggested in this dissertation is ef...