چكيده به لاتين
In this research, numerical simulation of vertical axis wind turbines in the combination of two wind turbines with different geometry has been performed to evaluate their performance. For this purpose, at first and with using of Fluent software and simulation of a two-dimensional geometry, the best turbulence model will be selected from the two models K-w SST and TRANSITION SST to be used for other simulations. Next, based on a helical wind turbine geometry (Darrieus), the numerical simulation method and the turbulence model will be validated for the three-dimensional geometry. For innovation, three Savonius-Darrieus geometries with different arrangements will be used for the savonius blades. In these three geometries, the helical blade section will not change from the validation section geometry, and only the savonius geometry will be added to the set located at the center of the wind turbine. According to this, in geometry number three, the blades of savonius will be located in the center of the blades of Darrieus. Then in geometry number four, the blades of savonius are in the center of the blades of Darrieus, but their radius will be half that of geometry number three. In geometry number five, the blades of savonius will be placed above the blades of Darrieus. The results showed that the pressure coefficient changes in different TSR s, do not have the same slope and also do not change uniformly and similarly with TSR. Also at high TSRs, the relative velocity is greater than relative velocity at low TSRs, which makes the boundary layer thinner than boundary layer at smaller TSRs. When the boundary layer grows as the height of the blade surface roughness, it causes a sudden increase in viscous force on the blades. Due to the viscous force, the power and the power coefficient will decrease. The results also show that in low TSRs, the smaller radius of the savonius blades cause the higher power
