Implementation of the volume-of-fluid (VOF) color function C advection algorithm on general moving grids. The algorithm is based on the piecewise linear interface construction (PLIC) method suitable for using general grids. The construction of the regions containing the fluid passing through cell-faces in a single time-step takes into account the relative velocity in the moving cell corners. The accuracy of the presented advection algorithm is comparable with similar fixed grids algorithms, while the applicability on r-adaptive grids enables a considerable reduction in the number of grid cells.
COBISS.SI-ID: 11610395
The paper presents a procedure for hydraulic design and analysis of the blade geometry of a high specific speed runner of the Saxo-type double-regulated vertical axial turbine. The meridional through-flow in the passage from the conical guide vane apparatus to the draft-tube elbow is designed by a novel streamline curvature method (SCM). To validate the design method and predictions and to investigate the design duty point and a number of off-design operating regimes, an extensive CFD simulation inside the entire turbine water-passage is performed. The flow patterns downstream the guide vane apparatus and the runner exit flow are analyzed. The focus of the analysis is on distribution of the angular momentum alongside the turbine, as well as on its impact on the flow around the runner blades. The SCM design procedure presented in the paper proves to be a robust and accurate tool for the runner blade row design.
COBISS.SI-ID: 11820315
Objective: In this study, different modifications of bottom spray fluid-bed coater with draft tube inserted were characterized and evaluated. Materials and methods: After coating the neutral pellets with polymeric solution comprising coloring agent pellet batches were characterized for coating variation, yield and degree of agglomeration. Results: Funnel-shaped distribution plate was found to improve process yield and decrease the degree of agglomeration at selected values of process parameters, whereas coating uniformity was worse in all cases when compared to conventional Wurster chamber. Results of the coating chamber with the swirl airflow generator indicate more uniform deposition of the coating material and in some cases an improved process yield and decreased formation of agglomerates when compared to conventional Wurster chamber. In series of experiments using Wurster chamber, having tangentially oriented air intake slots, which enabled introduction of air above the distribution plate, coating layer was more uniformly deposited on the pellet cores and formation of agglomerates was lower compared to the results obtained in a conventional Wurster coating chamber. Conclusion: Modifications of Wurster coating process by introducing swirling air motion within the draft tube or by introduction of air above the distribution plate have at selected values of process parameters resulted in reduced per-particle coating variation, degree of agglomeration and improved process yield.
COBISS.SI-ID: 3105137