The use of diffusers around the horizontal-axis wind turbines has been widely studied since the diffuser improves the power coefficient of the turbine and it is often called DAWTs （diffuser augmented wind turbines）....The use of diffusers around the horizontal-axis wind turbines has been widely studied since the diffuser improves the power coefficient of the turbine and it is often called DAWTs （diffuser augmented wind turbines）.Turbines using diffuser are called DWATs （Diffuser Augmented Turbines）,and have efficiency bigger than the Betz limit （maximum energy flow extracted = 59.26%）. Thus, this study presents a mathematical model describing the behavior of the velocity profile internally to a diffuser according to the characteristics of flow and geometry of a conical diffuser. The results are compared with experimental data and show good agreement.展开更多
Wind-lens turbines(WLTs)exhibit the prospect of a higher output power and more suitability for urban areas in comparison to bare wind turbines.The wind-lens typically comprises a diffuser shroud coupled with a flange ...Wind-lens turbines(WLTs)exhibit the prospect of a higher output power and more suitability for urban areas in comparison to bare wind turbines.The wind-lens typically comprises a diffuser shroud coupled with a flange appended to the exit periphery of the shroud.Wind-lenses can boost the velocity of the incoming wind through the turbine rotor owing to the creation of a lowpressure zone downstream the flanged diffuser.In this paper,the aerodynamic performance of the wind-lens is computationally assessed using high-fidelity transient CFD simulations for shrouds with different profiles,aiming to assess the effect of change of some design parameters such as length,area ratio and flange height of the diffuser shroud on the power augmentation.The power coefficient(Cp)is calculated by solving the URANS equations with the aid of the SST k–ωmodel.Furthermore,comparisons with experimental data for validation are accomplished to prove that the proposed methodology could be able to precisely predict the aerodynamic behavior of the windlens turbine.The results affirm that wind-lens with cycloidal profile yield an augmentation of about 58%increase in power coefficient compared to bare wind turbine of the same rotor swept-area.It is also emphasized that diffusers(cycloid type)of small length could achieve a twice increase in power coefficient while maintaining large flange heights.展开更多
文摘The use of diffusers around the horizontal-axis wind turbines has been widely studied since the diffuser improves the power coefficient of the turbine and it is often called DAWTs （diffuser augmented wind turbines）.Turbines using diffuser are called DWATs （Diffuser Augmented Turbines）,and have efficiency bigger than the Betz limit （maximum energy flow extracted = 59.26%）. Thus, this study presents a mathematical model describing the behavior of the velocity profile internally to a diffuser according to the characteristics of flow and geometry of a conical diffuser. The results are compared with experimental data and show good agreement.
文摘Wind-lens turbines(WLTs)exhibit the prospect of a higher output power and more suitability for urban areas in comparison to bare wind turbines.The wind-lens typically comprises a diffuser shroud coupled with a flange appended to the exit periphery of the shroud.Wind-lenses can boost the velocity of the incoming wind through the turbine rotor owing to the creation of a lowpressure zone downstream the flanged diffuser.In this paper,the aerodynamic performance of the wind-lens is computationally assessed using high-fidelity transient CFD simulations for shrouds with different profiles,aiming to assess the effect of change of some design parameters such as length,area ratio and flange height of the diffuser shroud on the power augmentation.The power coefficient(Cp)is calculated by solving the URANS equations with the aid of the SST k–ωmodel.Furthermore,comparisons with experimental data for validation are accomplished to prove that the proposed methodology could be able to precisely predict the aerodynamic behavior of the windlens turbine.The results affirm that wind-lens with cycloidal profile yield an augmentation of about 58%increase in power coefficient compared to bare wind turbine of the same rotor swept-area.It is also emphasized that diffusers(cycloid type)of small length could achieve a twice increase in power coefficient while maintaining large flange heights.
