Computational simulation of turbulent single-phase and multi-phase flows

Computer simulation of single phase and multi-phase flows has become an increasingly useful tool for both basic research and industrial designs. This thesis uses KIVA-3 to examine three problems that have direct industrial applications. Each of these three problems addresses either a phenomenon that has not been quantified before, or improves previously existing methodology to further the understanding. In the first problem, erosion in a pipebend caused by particle impingement in a pneumatic transport system is studied. This is the first numerical investigation done by using Computational Fluid Dynamics (CFD) to quantify the erosion rate in a pneumatic transport system. In this study the effects of pipe bend curvature, particle size and inflow velocity have been investigated. The most frequently impacted location on the pipebend for different radius of curvature are determined computationally. The second problem studied is about the particle distribution in a pipe branch with variable area ratio. The distribution of total mass flow rate into branches is investigated under different particle size and area ratio of pipe branches by using CFD. Such studies have only been done experimentally with a limited range of parameters. The results show that as the particle size decreases the deviation of mass flux distribution in the branches from the area ratio increases rapidly. The third case studied is the flow pattern inside a centrifugal compressor. A full three-dimensional Navier-Stokes numerical simulation has been performed for the first time on the vaneless diffuser and volute of a centrifugal compressor. The Martin-Hou equations are applied for the vapor refrigerant computation. A possible improvement in design is evaluated. In addition to contributing to better quantification of these practical problems, this thesis also discusses the difficulties that still exist in carrying out Computational Fluid Dynamics studies.