A two and three-dimensional CFD investigation into performance prediction and wake characterisation of a vertical axis turbine

Abstract

The emergence of tidal energy as a key renewable energy source requires the development of computational design models for accurate prediction of turbine performance and wake effects whilst also being computationally efficient. In this paper, we develop and validate a three-dimensional CFD model for vertical axis turbines, which achieves high accuracy. We also investigate the limitations of two-dimensional models and present a blockage correction for improved prediction. The two-dimensional blockage correction model is potentially attractive for preliminary design studies due to its computational advantage over three-dimensional models.

A CFD investigation of a variable-pitch vertical axis hydrokinetic turbine with incorporated flow acceleration

“…the sum of the bluff body and turbine entrance areas), and ∞ is freestream velocity. More detail on the experimental testing is available in Mannion, et al (2018a). Reproduced with permission from Mannion, et al (2018a).…”

“…1. Turbine position: the present turbine location relative to the static parts of the device was chosen based on experimental studies of flow acceleration around the bluff body (Mannion, et al 2018a) which found that maximum localised flow acceleration occurred at the widest point of the bluff body. To investigate whether this is indeed the optimum position for the turbine, two models are used where the turbine is moved downstream from its present position by 100 mm and 200 mm (parallel to the flume).…”

“…Two significant features of the device are: (1) the central bluff body accelerates the entrance velocities to the turbines and (2) the variable-pitching turbine blades that are designed to maximise hydrodynamically induced torque on the generator shaft. Scaled prototypes of the turbine have been tested in a recirculating flume (Mannion, et al 2018a) and in the field. Reproduced with permission from Mannion, et al (2018a).…”

“…Scaled prototypes of the turbine have been tested in a recirculating flume (Mannion, et al 2018a) and in the field. Reproduced with permission from Mannion, et al (2018a).…”

Numerical Simulation of the Flow around a Straight Blade Darrieus Water Turbine

“…As a main result, the presence of winglets predicted in all considered cases an improvement in turbine efficiency which was estimated in around 20% for a symmetric hybrid fence-raked winglet regarding the straight blade case. Mannion et al [28] implemented 3D CFD simulations of a tidal turbine using ANSYS Fluent v17 and the SST turbulence model in both versions, standard and transitional. Meshes of up to 22 million elements where used reporting satisfactory grid convergence.…”