Numerical Simulation On Multi-phase Flow In Concrete Mixing & Transporting Vehicle

As a main construction material, the mixing quality of concrete behaves especially important. As the result of regulation put up by the nation"No mixing locally", then we must use commercial concrete in the project, so the transportation of concrete becomes an industry. If the concrete transportation should undergo a long distance or a long time period that it goes beyond the time limit, and at the same time, you transport the concrete with a common transportation machine but not concrete mixing transportation device, the quality of concrete will become a problem, such as the layered isolation, even become concreting, and it makes an effect on the quality of concrete. In this case, in order to adapt to the transportation of commercial concrete, concrete mixing transporting vehicle has been developed rapidly these years. To the design, optimization, usage and engineering construction, numerical simulation on multi-phase flow in concrete mixing & transporting vehicle has an important realistic sense.The mixing canister is the most important part in concrete mixing transporting vehicle used to load and transport the mixed concrete. In this paper, the development of concrete mixing transporting vehicle and the study of multi-phase flow is presented, and also the definition of concrete and concrete mixing transporting vehicle, especially the structure and working principles, the study methods of multi-phase flow and which method is adopted in this paper.The flow in canister belongs to thick-density multi-phase flow, and the flow pattern is extremely complex. Recurred to the large three dimension modeling software CATIA and the commercial CFD software, the flow characteristics of mixing canister, the mixing device of concrete mixing transporting vehicle is discussed in the paper. Here is some work done in the paper.(1) Mixture Model and VOF Model of Euler-Euler method are chosen here to simulate and calculate respectively, and after comparing several kinds of numerical simulation methods, FVM is adopted.(2) In order to simplify the process of modeling and meshing, some hypothesis are made right to the structure, working status and flow field of the canister, and also some subordinate elements are ignored.(3) Meshing model of the flow field is built with meshing built tool in CFD, in this basis, the solvers, turbulent models, strategies for coupling the velocity and pressure and space discretization formats provided in CFD software are compared and analyzed. Then separated solver is adopted; to turbulent models, RNG k ?εmodeling is chosen; to schemes for coupling the velocity and pressure, PISO is chosen; first upwind method is used to accomplish the space dicretization.(4) Boundary condition is defined, including the canister wall and mixing vane in the simulated area are defined rotational, MRF is applied to simulate the flow flied, and the initial values are defined, too.(5) Mixture Model is adopted to simulate phase separation, and VOF is used to simulate the free surface of the mixer and the pressure and velocity, at the same time, some proposals on design are put forward.There are some simplification and supposal made in the paper, which make the differences between the real flow instance and the simulative instance in mixing canister in concrete mixing transporting vehicle, so the results after simulation about the interior flow can only seize the probable instance, however, they make great sense to the next step to study thoroughly and to instruct the design of mixing canister.