In this work the effects of various shroud types and flange thicknesses on the performance of a micro wind turbine are studied. For the first time the micro wind turbine has been simulated inside the shroud, simultaneously. Two 3D models, one of an airfoil-revolved shroud and the other of a nozzle-diffuser shroud inspired by the geometry of the airfoil-based shroud, have been simulated in order to compare the results. Moreover, for the first time in the literature the thickness of the flange has been changed to study its effect on the Turbine efficiency. It is evident from the results that the micro wind turbine experiences the highest increase in output power when equipped with a nozzle-diffuser shroud featuring a thick flange. The power coefficient in this instance is 0.313, indicating a 125% increase compared to the bared wind turbine and a 32% increase compared to the flangeless nozzle-diffuser case.
AbbottIVon DoenhoffAE (1959) Theory of Wing Sections. New York: Dover Publications.
2.
AbeKOhyaY (2004) An investigation of flow fields around flanged diffusers using CFD. Journal of Wind Engineering and Industrial Aerodynamics92(3–4): 315–330. DOI: 10.1016/j.jweia.2003.12.003.
3.
AbeKNishidaMSakuraiA, et al. (2005) Experimental and numerical investigations of flow fields behind a small wind turbine with a flanged diffuser. Journal of Wind Engineering and Industrial Aerodynamics93(12): 951–970. DOI: 10.1016/j.jweia.2005.09.003.
4.
AvalloneFRagniDCasalinoD (2020) On the effect of the tip-clearance ratio on the aeroacoustics of a diffuser-augmented wind turbine. Renewable Energy152: 1317–1327. DOI: 10.1016/j.renene.2020.01.064.
5.
BontempoRDi MarzoEMMannaM (2023) Diffuser augmented wind turbines: a critical analysis of the design practice based on the ducting of an existing open rotor. Journal of Wind Engineering and Industrial Aerodynamics238: 105428. DOI: 10.26233/heallink.tuc.99236.
6.
El-ZahabyAMKabeelAEElsayedSS, et al. (2017) CFD analysis of flow fields for shrouded wind turbine’s diffuser model with different flange angles. Alexandria Engineering Journal56(1): 171–179. DOI: 10.1016/j.aej.2016.08.036.
7.
ForemanKGilbertBOmanR (1978) Diffuser augmentation of wind turbines. Solar Energy20(4): 305–311. DOI: 10.1016/0038-092X(78)90122-6.
8.
GhafoorianFMirmotahariSREidizadehM, et al. (2024) A systematic investigation on the hybrid Darrieus-Savonius vertical axis wind turbine aerodynamic performance and self-starting capability improvement by installing a curtain. Next Energy6: 100203. DOI: 10.1016/j.nxener.2024.100203.
9.
GilbertBLOmanRAForemanKM (2012) Fluid dynamics of diffuser-augmented wind turbines. Journal of Energy2(6): 368–374. DOI: 10.2514/3.47988.
10.
HansenMOLSorensenNNFlayR (2000) Effect of placing a diffuser around a wind turbine. Wind Energy3(4): 207–213. DOI: 10.1002/we.37.
11.
IgraO (1977a) Compact shrouds for wind turbines. Energy Conversion16(4): 149–157. DOI: 10.1016/0013-7480(77)90022-5.
12.
IgraO (1977b) The shrouded aerogenerator. Energy2(4): 429–439. DOI: 10.1016/0360-5442(77)90006-8.
13.
IgraO (1981) Research and development for shrouded wind turbines. Energy Conversion and Management21(1): 13–48. DOI: 10.1016/0196-8904(81)90005-4.
14.
KardousMChakerRAlouiF, et al. (2013) On the dependence of an empty flanged diffuser performance on flange height: numerical simulations and PIV visualizations. Renewable Energy56: 123–128. DOI: 10.1016/j.renene.2012.09.061.
15.
KhamlajTARumpfkeilMP (2018) Analysis and optimization of ducted wind turbines. Energy162: 1234–1252. DOI: 10.1016/j.energy.2018.08.106.
16.
KhojastehHNorollahiYTahaniM, et al. (2020) Optimization of power and levelized cost for shrouded small wind turbine. Inventions5(4): 1–13. DOI: 10.3390/inventions5040059.
LipianMDobrevIKarczewskiM, et al. (2019) Small wind turbine augmentation: experimental investigations of shrouded- and twin-rotor wind turbine systems. Energy186: 115855. DOI: 10.1016/j.energy.2019.115855.
19.
LipianMDobrevIMassouhF, et al. (2020) Small wind turbine augmentation: numerical investigations of shrouded- and twin-rotor wind turbines. Energy201: 117588. DOI: 10.1016/j.energy.2020.117588.
20.
MaftouniNBarghiY (2023) An innovative design of INVELOX wind turbine: a numerical study on the effects of implementing long flange and Venturi holes. Transactions of the Canadian Society for Mechanical Engineering47(1): 162–174. DOI: 10.1139/tcsme-2022-0025.
21.
MaftouniNTaghaddosiM (2022) A CFD study of a flanged shrouded wind turbine: effects of different flange surface types on output power. Scientia Iranica29(1): 101–108. DOI: 10.24200/SCI.2021.57513.5278.
22.
MatsushimaTTakagiSHMuroyamaS (2006) Characteristics of a highly efficient propeller type small wind turbine with a diffuser. Renewable Energy31(9): 1343–1354. DOI: 10.1016/j.renene.2005.07.008.
23.
MirmotahariSRGhafoorianFMehrpooyaM, et al. (2025) A comprehensive investigation on Darrieus vertical axis wind turbine performance and self-starting capability improvement by implementing a novel semi-directional airfoil guide vane and rotor solidity. Physics of Fluids36: 065151. DOI: 10.1063/5.0208848.
24.
OhyaYKarasudaniT (2010) A shrouded wind turbine generating high output power with wind-lens technology. Energies3(4): 634–649. DOI: 10.3390/en3040634.
25.
OhyaYKarasudaniTSakuraiA, et al. (2008) Development of a shrouded wind turbine with a flanged diffuser. Journal of Wind Engineering and Industrial Aerodynamics96(5): 524–539. DOI: 10.1016/j.jweia.2008.01.006.
26.
PambudiNAPristiandaruDLBasorim WijayantoDS, et al. (2017) Experimental investigation of wind turbine using nozzle-lens at low wind speed condition. Energy Procedia105: 1063–1069. DOI: 10.1016/j.egypro.2017.03.459.
27.
PambudiNAPambudiNAFebriyantoR, et al. (2019) The performance of shrouded wind turbine at low wind speed condition. Energy Procedia158: 260–265. DOI: 10.1016/j.egypro.2019.01.086.
28.
ParsaHMaftouniN (2020) Optimization of a real scale shrouded wind turbine using 3D CFD analysis. International Journal of Renewable Energy Research10(2): 922–932. DOI: 10.20508/ijrer.v10i2.10916.g7959.
29.
PhillipsDGFlayRNashTR (1998) Aerodynamic analysis and monitoring of the Vortec diffuser augmented wind turbine. In: IPENZ Conference 1998. Auckland, New Zealand.
30.
RajUINairAS (2009) Development of 3d CFD model of a shrouded wind turbine. In: 10th National Conference on Technological Trends. Kerala, India.
31.
SaidMEL-ShimyMAbdelraheemMA (2017) Improved framework for techno-economical optimization of wind energy production. Sustainable Energy Technologies and Assessments23: 57–72. DOI: 10.1016/j.seta.2017.09.002.
32.
SangoorAJ (2018) Experimental and Computational Study of the Performance of a New Shroud Design for an Axial Wind TurbineMaster Dissertation. Youngstown University. https://hdl.handle.net/1989/11606.
33.
ShivesMCrawfordC (2010) Computational analysis of ducted turbine performance. In: Proceedings of the 3rd International Conference on Ocean Energy. Bilbao.
34.
SiavashNKNajafiGTavakkoli HashjinT, et al. (2020a) An innovative variable shroud for micro wind turbines. Renewable Energy145: 1061–1072. DOI: 10.1016/j.renene.2019.06.098.
35.
SiavashNKNajafiGHashjinTT, et al. (2020b) Mathematical modelling of a horizontal axis shrouded wind turbine. Renewable Energy146: 856–866. DOI: 10.1016/j.renene.2019.07.022.
36.
TaghizadehJAbdoliSHSilvaV, et al. (2023) Computational fluid dynamic and response surface methodology coupling: a new method for optimization of the duct to be used in ducted wind turbines. Heliyon9(6): e17057. DOI: 10.1016/j.heliyon.2023.e17057.
37.
WangFBaiLFletcherJ, et al. (2008) The methodology for aerodynamic study on a small domestic wind turbine with scoop. Journal of Wind Engineering and Industrial Aerodynamics96(1): 1–24. DOI: 10.1016/j.jweia.2007.03.004.
38.
YounoussiSEttaouilA (2024) Calibration method of the k-ω SST turbulence model for wind turbine performance prediction near stall condition. Heliyon10: e24048. DOI: 10.1016/j.heliyon.2024.e24048.
