Influence of Axial Distance and Duct Angle in the Improvement of Power Generation in Duct Augmented Wind Turbines

Abstract

Diffuser augmented wind turbines (DAWTs) are incredibly beneficial to low wind speed areas. The duct that surrounds the turbine improves the power output by accelerating the approaching wind directing the wind through the blade. The power output of DAWT mainly depends on the duct length by turbine diameter (L/D) ratio, duct angle, axial distance, and tip clearance between the blade and duct. This article gives an insight into the performance variation of DAWT for various duct L/D ratios. Numerical simulations were performed on DAWT using ANSYS FLUENT and the performance characteristics were studied for different duct L/D ratios, duct angles, and axial distance. The investigations found that axial distance of 0.06 D for duct L/D ratios between 0.15 to 0.60 gives improved performance. It was found that the optimal duct angle is a function of the L/D ratio, and as the L/D ratio increases, the duct angle increases. A geometric procedure was used to find the pattern in which the angle increases in other L/D ratios. The geometric procedure helps to keep the duct's inner profiles merging for duct L/D ratios 0.15 to 0.6 by maintaining constant axial distance. By keeping the ducts as per the proposed procedure resulted in angles 22 deg, 38 deg, 45 deg, and 52 deg for duct L/D = 0.15, 0.3, 0.45 and 0.6. The performance of WT with 30 deg angled ducts and proposed angled ducts were compared. The proposed angled ducts had improved power output than 30 deg angled ducts. The proposed axial distance and duct angles help to use the duct length effectively, which shortens the duct and enhances power output.

Velocity Augmentation Model for an Empty Concentrator-Diffuser-Augmented Wind Turbine and Optimisation of Geometrical Parameters Using Surface Response Methodology

“…In the present study, six geometrical parameters were identified from the literature: diffuser angle (𝜃 ), concentrator angle (𝜃 ), concentrator length (𝐿 ), diffuser length (𝐿 ), Research studies have indicated that these parameters affect the velocity augmentation of the diffuser-augmented wind turbine (DaugWT), the concentrator-augmented wind turbine (CaugWT), and the CDaugWT [26,29,55,56]. However, most of these studies focused on analysing each parameter's influence independently, while other parameters were held constant [42,57,58]. The present study investigated the interaction between these parameters and their contribution towards velocity augmentation.…”

“…Notably, it is suitable for adverse pressure gradients, insensitive to free-stream turbulence in the far wake region, and eliminates the need for damping functions [72]. The model choice was based on extensive literature recommendations for aerodynamic purposes, especially in shrouded wind turbines [9,11,12,37,40,42,[67][68][69][72][73][74][75][76][77][78].…”

“…Ramayee and Supradeepan [42] conducted an optimisation study on a shrouded wind turbine enclosure using numerical simulations and the design of experiments (DOE) approach. The study identified optimal parameters, including a shroud length-to-diameter (L/D) ratio of 0.4, shroud angle of 9 • , flap L/D ratio of 0.2, flap angle of 16 • , and a radial distance of 0.2R.…”

Optimization Based on Computational Fluid Dynamics and Machine Learning for the Performance of Diffuser-Augmented Wind Turbines with Inlet Shrouds

“…Applying CFD techniques to analyze the aerodynamics of wind turbines enables a deeper understanding of fluid dynamics within the wind field, thus enabling precise predictions of turbine performance [40,41]. Such a statement is evident from the review of the above papers, and it can be found that most of the above studies were conducted using computational fluid dynamics (CFD), such as Abe and Ohya [19], Abe et al [20], Jafari and Kosasih [22], Roshan et al [23], El-Zahaby et al [24], Heikal et al [27], Klistafani and Mukhsen [28], Anbarsooz et al [29], Arifin et al [30], Ramayee and Supradeepan [32], Hashem et al [33], Jauhar et al [34], Mutasher et al [35], Hashem et al [38], Avallone et al [39], etc. ; and the review paper by Agha et al [42] also emphasized that CFD plays a vital role in the design and performance improvements of the DAWT.…”

“…The influences of rotor axial position, diffuser length, and opening angle on the power generation of DAWTs were numerically studied by Ramayee and Supradeepan [32]. Their parametric studies showed that the optimal diffuser opening angle is a function of its length, so it should not be fixed and has to be kept as a variable when changing the diffuser length.…”