| Title |
Effect of Winglet on Wind Turbine Performance
and Wake Characteristics |
| Type |
PhD |
| Supervisors |
Prof.Dr.Samir Sobhy Ayad
Prof.Dr.Osama Ezzat Abdellatif
Prof.Dr.Tarek Abdelamalak Mekhail
Dr. Ibrahim Mahmoud Shahin |
| Year |
2020 |
| Abstract |
Winglet (WL) has recently been used to improve the performance of horizontal axis wind
turbine (HAWT). The WL geometry is a key parameter for diverging blade tip vortices away
from turbine blades and reducing their induced drag. The present study focuses on the effect of
winglet height (H) and toe angle (α
w
) on the turbine performance and turbine wake
characteristics. Both computational and experimental investigations are carried out.
The performance of a three-bladed rotor of 1m diameter with SD8000 aerofoil is
numerically investigated using ANSYS 17.2 CFD on a polyhedral mesh. The model is hence
validated by comparing results for power coefficient (C
pw
) with experimental values available
in the literature. The pressure coefficient (C
p
) results around blade aerofoil are compared to
those of the literature. Four upwind WLs with different values of H are considered while
keeping α
w
constant at 0
o
. The winglet of H=0.8%R is proved to be the best height for
performance enhancement. It increases C
pw
by 2.4% at tip speed ratio =7.
The toe angle effect is studied for upwind and downwind WLs while keeping H=0.8%R.
The results show that C
pw
increases as α
w
increases up to α
w
=+20
o
ii Abstract
at all values of . C
pw
increases by 6% at =7. Downwind WL always reduces C
pw
. The present results are well
explained by the resulting vectors map near the blade tip. Using WL with the optimum H and
α
w
, causes 6% increase in C
pw
as compared to rotor blades without WL.
The effects of four selected WLs namely H=8%R, H=0.8%R (α
w
=0), α
w
=30
o
(H=0.8%R) on the wake up to X/R=5.4 downstream of the turbine are studied numerically
at λ=7. The optimum WL (H=0.8%R and α
w
=+20
o
) increases the velocity deficit in the mixing
region as a result of thrust increase. It produces higher Reynolds’s shear stress and wider
mixing region by comparison to the other WLs. The results prove that optimum winglet plays
crucial role in wake re-energizing process.
Experiments are performed using free-jet wind tunnel and three-dimensional printed
model with the same CFD model dimensions. Four samples of WLs are manufactured for the
experimental study. The WL of α
w
=+20
o
shows experimentally the same percent of power
enhancement (6% at λ=7) that is previously predicted by the present CFD. |
| Keywords |
Wind Turbine, Winglet, Wakes, CFD, Toe angle |
| University |
Benha University |
| Country |
Egypt |
| Full Paper |
download paper
|
