مهندسی مکانیک شریف (Nov 2020)
DARRIEUS WIND TURBINE PERFORMANCE ENHANCEMENT USING VARIOUS FLOW CONTROL TECHNIQUES AND COMPARISON
Abstract
In this paper performance of vertical-axial wind turbine has been studied based on 5 different flow control techniques. The active methods selected here are suction and blowing and the passive methods are composed of using riblet, cavity and porous media, which the latter one is a new method. The benchmark turbine selected here is Darrieus type and the performance parameter is considered as power coefficient of the turbine. The geometry, location and depth of the actuators are assumed to be approximately equal in different methods aiming the better comparison. Two-dimensional CFD and flow simulation was carried out in Star-ccm+ software. The governing equations are unsteady Navier-Stokes equations and turbulence model is selected k-\u{03b5}. The numerical result of the original wind turbine has been validated against experimental data. Then for each control method, numerical solution has been performed and being evaluated. The results show that the power coefficient or efficiency could be improved as much as the control method would reduce the wake region. The results also show that the blowing and suction control methods with about 6\% improvement for TSR 1.7 and 2.64 have the better performance among all other methods. Using porous media as a new control method, improves power by about 1\% in TSR 1.7. Considering the advantages in noise reduction, this new technique may be further investigated. In this paper also parametric study of each control methods have been performed. The change in power coefficient depends on both TSR and actuator intensity. Based on the numerical simulations it is recommended that a hybrid layout consisting active and passive flow control method applied over turbine blades.
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