On the actual power coefficient by theoretical developing of the diffuser flange of wind-lens turbine

The wind-lens technology attracts extensive attention due to its promising performance. A numerical study was carried out to investigate the effects of diffuser flange inclination angle (φ) and the diffuser flange depth inside the exit of the diffuser (hi/Drotor) on the wind-lens turbine system performance. Besides, the effect of wind speed is taken into consideration. φ is changed through the range of −15° to 15° with a step of 5° in both forward and backward directions. Also, hi/Drotor is changed through the range of 0-0.06 with a step of 0.02 and wind speed of (8 and 10 m/s). A CFD model was developed and solved by using ANSYS FLUENT 16.2. Such model was validated by using previous published experimental results with good agreement and maximum deviation of 2.4%. It was found that the percentage increase of Cp at different values of φ was increased by augmenting of λ. Thus, it is emphasized that the maximum percentage increase of Cp of 28% was obtained at λ of 5.6 and φ of 10°. Moreover, a theoretical correction of Cp was performed to achieve that the actual power coefficient Cpact never exceeds Betz limit.