Conference Publication Details
Mandatory Fields
Mulligan, S., Bonfils, T., O’Neil, C., Gonzalez, B., Carty, A., Clifford, E., Nash, S.
Civil Engineering Research Ireland (CERI) 2018
Multiphase numerical modelling of tangential inlet vortex drop shaft structures.
Optional Fields
Vortex dropshafts; energy dissipation, combined sewer overflows, numerical modelling
Vortex drop shaft structures are a popular means of dropping large amounts of water, safely and efficiently, through considerable elevation differences. As a result, these types of hydraulic structures have seen application in deep tunnel conveyance and storage systems. The structure operates by converting linear water flows into rotation through a vortex generator with a tangential inlet causing the downstream flow to ‘cling’to the walls of the shaft thus enhancing frictional energy dissipation. Due to the complex flow patterns existing within the structure, many elements of the system are still not fully understood thus instigating the need for costly physical modelling programs. In this study, three-dimensional multiphase numerical modelling is applied to the classic tangential inlet vortex drop shaft with a supercritical approach flow. The validation study was performed using ANSYS CFX and FLUENT which both use Eulerian-Eulerian approaches to resolve the multiphase transport equations. The numerical model is compared with free-surface and velocity information gathered from a 1/10 scaled physical model of the flow system for validation. The study found that the solution was largely dependent on the mesh density and inflation layers along the walls of the dropshaft and was less dependent on the choice of turbulence model. Solution errors in the range of 5 to 10% were observed. The paper outlines methods which may help fast track future numerical model investigations on vortex drop shaft structures.
Grant Details
Publication Themes
Environment, Marine and Energy