Effects of gurney flap on the performance of diffuser augmented wind turbines

In this paper, a numerical investigation on the effect of gurney flap (GF) on the performance of a diffuser augmented wind turbine (DAWT) is presented. The flow-field around the DAWT is obtained by solving the Reynolds-averaged-Navier-Stokes (RANS) equations. The turbine is modelled as an uniformly loaded actuator disc (AD) that imposes a resistance to the passage of the flow. Comparison of the numerical results with experimental measurements in similar conditions shows that the numerical approach used satisfactorily reproduces the mean flow field. GF heights equal to 2% and 4% of the diffuser chord length were investigated. Results show that separation induced by GF creates a low pressure region at the diffuser exit, that increases the mass flow through the diffuser and the power coefficient of the DAWT.