Study On Finite Element Simulation Of Mixing Process Of Mixed Mortar And Optimization Of Key Mixing Equipment Structural Parameter

Dry-mixed mortar is another kind of new green building material which is usedwidely following the concrete. Dry mortar mixing equipment is one of the most keyequipments in dry mortar production line. At present, although there are manyexperimental and theoretical studies about mixing equipments, theoretical research anddesign calculation methods are still not good enough. Structure optimization design andkey parameters selection of mixing equipment are more dependent on experiments,which will take large amounts of time and money. In recent years, with the developmentof computer technology, the numerical simulation and analysis has become an effectivemethod to resolve complex problems. In this dissertation, study of dry-mixed mortarmixing process was performed by finite element simulation technology. The physicalphenomena and movement law of materials were explored and the characteristics ofmixing process were analysed. On this basis, the key structural parameters of the mixingequipments were optimized and designed, which provide theoretical evidence andtechnical guidance for improving the structure of mixing equipment and developingnew product.At first, the fundamental theories and key technologies of finite element simulationof mixing process were researched. The geometric dimensions of the dry-mixed mortarcomponents were defined. Continuous model was used to describe the physicalcharacteristics of particle movement of dry-mixed mortar according to powder theory.Key technologies which were used in the finite element simulation of mixing processwere put forward, including multiphase flowing continuum model, fluid basic controlequation and RNG k turbulence model.Secondly, the dry mortar mixing equipment DW1200was taken for the researchobject. The physical model of the mixing equipment was simplified reasonably.Three-dimensional solid model were created in UG software. Finite element simulationwas in ANSYS software. The Variation curve about the change of variation coefficientwith the time was got by the dry mortar mixing experiments. The results of finiteelement simulation and experiments were compared and analysed, and the consistency was obtained, which shows that the key technologies developed in this dissertation areright.And then, using the above finite element simulation technologies, mixing processof material in dry mortar mixing equipment DW2000which is often used in actualproject was analyzed. The velocity field, turbulent kinetic energy field, volumedistribution of material and the tracer concentration field were obtained. The studyresults show that the speed of the material movement along the radial increasesgradually and gets the biggest under the effect of the lateral blades. The speed is thesmallest near the shaft and stirring arm. The turbulent kinetic energy mainlyconcentrates nearby areas of the blades and the region between the blades. Turbulentkinetic energy is very small near the wall and stirring shaft. The tracer moves along thetangential and axial direction under the stirring of blades and slowly moves to the rest ofblades and forms convection mixing. Under the effect of the blades, the shear layerforms between each other. Tracer particles slide and collides each other, which aresubject to considerable shear stress and forms hear mixing.At last, key structural parameters which have impacts on mixing process of mixingequipments were discussed and compared. Based on the finite element simulation, thekey structural parameters were optimized and designed, including installation angle ofblades, the numbers of blade and the position of adding material. The study results showthat in terms of the installation angle of blades, the mixing effect of the mixingequipment with installation angle of45degrees is the best. With the increase of the shaftspeed, the mixing time is shorter, but the power consumption is more. The mixingequipment with eight blades needs shorter time, and mixing efficiency is higher. In theadding position, the adding points of tracer are close to the position of blades, and thetracer spread faster and mixing time is shorter.