Research development related to Diffuser Augmented Wind Turbine (DAWT) is very important, in order to
optimize renewable energy sourced from wind energy. The purpose of the research conducted to determine the effect of
adding flange to increase the performance of DAWT and to find out the optimal angle of the flange. The other aims of
the research are discovering the fluid flow phenomenon that occurs in the curved diffuser augmented wind turbine which
is equipped with flange. The method used in numerical simulations was Computational Fluid Dynamics (CFD) method.
There were three procedures in this numerical research, namely pre-processing stage, solving stage and continued with
the post-processing stage. The studies demonstrate that the addition of flange to the curved diffuser has positive impact
on improving DAWT performance, because it can produce very significant wind speed increment compared to the curved
diffuser without flange. Curved diffuser flange 0° has the best performance. It can increase wind velocity up to 103.76%
in the midline axis of diffuser area with maximum wind velocity is 10.19 m/s. Based on visualization results, there is a very large vortex in the downstream area of curved diffuser flange 0° so it can enhanced the suction effect to generate the wind speed quality inside diffuser.
Keywords: CFD, diffuser, flange, wind turbine