CFD simulations for investigating the wake states of a new class of tidal turbine.

The interest of tidal energy exploitation is increasing in recent years promoting the need for development of efficient tidal turbines. This paper investigates the wake states of energy extraction by a new tidal turbine design, the Momentum Reversal Lift (MRL), developed by Aquascientific Ltd with a different method of tidal turbine modelling (body force) using an open source computational fluid dynamics (CFD) code, OpenFOAM. The body force CFD model results showed better turbulent patterns downstream of the turbine showing its quality compared to porous disc method which has been used for tidal turbine modelling. The simulations on a single MRL device showed that the wake recovers into 94% of the free stream at 20D downstream of the turbine. The performance of a downstream turbine simulated with 20D spacing was reduced by almost 7.17% due to the energy shadowing created by the upstream wake. Thus, it is necessary to have at least 20D turbine spacing to maintain more than 92% of the performance of an isolated turbine.