Performance Modeling of Ducted Vertical Axis Turbine Using Computational Fluid Dynamics

Vertical axisturbines (VATs) excel over horizontal axis turbines in their independent flow direction. VATs that operate in an enclosure, e.g., a diffuser shroud, are reported to generate more power than unducted VATs. A diffuser-shrouded, high solidity of 36.67%, three-blade VAT with, OACA 63(3)-018 airfoil section is modeled in 2-D using the, com merciatsoftware ANSYS-FLUENT (R). Incompressible, unsteady, segregated, implicit, and second order in time and space solver is implemented in association with the Spalart-Allmaras turbulent model with a reasonable compute' tional cost, The computations results are assessed against experimentai data for unducted VAT at lowtip Speed ratios between 1 and 2 for further numerical analysis on diffuser models. Different diffuser designs are investigated using suitable nozzle size, area ratio, length-to-diameter ratio and angles between the diffuser inner surfaces The numerical model; shows that fot a specific diffuser design, the ducted. VAT performance coefficient can he augmented by almost 90% over its unducted counterpart.