Author(s): Jacob Riglin; W. Chris Schleicher; Alparslan Oztekin
Keywords: Hydraulics of renewable energy systems; RANS models; rotating and swirling flows; three-dimensional models; turbulence modelling; turbulent wakes
Abstract: Computational fluid dynamics simulations were conducted for two diffuser designs that were added to a pre-existing horizontal axis hydro-kinetic turbine design. The two diffuser designs investigated in the present study had the area ratio values of 1.36 and 2.01. Each design used a short axial length to satisfy system portability constraints. The turbine-diffuser systems steady-state performance characteristics were assessed numerically. A structured, hexahedral mesh was employed to discretize the equations governing the fluid motion. Turbulent flow structures were captured through the implementation of the k-ω Shear Stress Transport (SST) model. A 39.5% and 55.8% increase in output mechanical power was observed versus the un-augmented turbine performance. As the area ratio increases from 1.36 to 2.01, the total thrust experienced by the unit nearly doubles.