Design of shorter duct for wind turbines to enhance power generation: a numerical study

• Published in: Journal of the Brazilian Society of Mechanical Sciences and Engineering Vol. 44; no. 4
• Main Authors: Ramayee, L., Supradeepan, K., Ravinder Reddy, P., Karthik, V.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-04-2022; Springer Nature B.V
• Subjects: Axial forces; Design of experiments; Design optimization; Engineering; Flow characteristics; Flow separation; Fluid flow; Mechanical Engineering; Technical Paper; Tip clearance; Tip speed; Turbine blades; Turbines; Velocity; Wind power; Wind turbines; Wind turbine design optimization; Shorter duct; Wind energy; DAWT; Ducted wind turbine; Shrouded turbine
• ISSN: 1678-5878; 1806-3691
• DOI: 10.1007/s40430-022-03457-3

Duct augmented wind turbines (DAWT) are extremely beneficial to areas with low wind speeds. The duct surrounding the turbine improves the power output by accelerating the approaching wind. This paper aims to design a shorter duct suitable to the wind turbine blade and enhance wind power. This article gives a performance variation of DAWT for various duct angles (
α
) at different input conditions. Numerical simulations were performed on the turbine with a duct with different input conditions using ANSYS Fluent. Based on the investigations, the appropriate operating condition of DAWT was chosen. The performance of DAWT at various duct angles was compared by fixing the operating conditions. The best duct angle in the investigated range was found as 30° at tip speed ratio
λ
= 6, which had the highest power output and attached flow. The turbine with chosen 30° angled duct is simulated for various velocity
V
and
λ
. The results show that the optimal duct angle changes with reference to the rotational speed and inlet velocity. At low rotational speed in DAWT, the flow behaves similarly to the bare duct; hence, flow separation occurs at the duct wall. The axial distance and tip clearance between the duct and blade were optimized using the design of experiments (DOE) approach. The flow characteristics of the bare duct, conventional, and chosen DAWT were compared. It was found that the ducted turbine’s blade had a higher axial force than the conventional at the same
V
and the same
λ
. The proposed design procedure helps achieve a higher power output with a shorter duct. Furthermore, a comparative analysis was conducted with the experimental data provided in the literature, indicating that the proposed DAWT gives improved performance.