Browsing by Author "Ianakiev, Anton"

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    Effect of blade shape on aerodynamic and aeroacoustic characteristics of vertical axis wind turbines using mid-fidelity and high-fidelity methods
    (AIAA, 2024-01-04) Thambidurai Arasi, Tarun Ramprakash; Shubham, Shubham; Ianakiev, Anton
    This research paper investigates the effect of different blade shapes on the aerodynamic and aeroacoustic characteristics of Darrieus Vertical Axis Wind Turbines (VAWTs). Three different VAWT blade shapes are investigated: Straight, Troposkein, and Helical, considering a chord-based Reynolds number of 1.73e+5 and at a constant tip speed ratio for all. The mid-fidelity Lifting Line Free Vortex Wake (LLFVW) method and the high-fidelity Lattice Boltzmann/Very Large Eddy Simulation (LB-VLES) method are employed. Power performance analysis reveals that the straight-bladed VAWT generates the highest power output (about 11% higher), followed by the helical and troposkein blade configurations. The helical-bladed rotor exhibits smoother thrust and torque distribution over a wider azimuthal angle range, as predicted by both methods. While both methods capture the same trends in thrust and torque values, the mid-fidelity LLFVW method predicts approximately 22% higher thrust and torque values and lower near-wake streamwise velocities as compared to the high-fidelity LBM. The LLFVW is unable to accurately capture the inherent 3D vortices in the VAWT flow-field and the effect of blade-vortex interaction (BVI) on the VAWT force-field, as compared to LBM. In terms of aeroacoustics, the troposkein VAWT produces the highest noise at lower frequencies (20-30 Hz), followed by the straight and helical VAWTs. However, the troposkein and helical VAWTs emit more noise at higher frequencies (500-2000 Hz) than the straight VAWT due to the higher intensity of BVI observed for the former.
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    Effect of struts and central tower on aerodynamics and aeroacoustics of vertical axis wind turbines using mid-fidelity and high-fidelity methods
    (AIAA, 2024-01-04) Shubham, Shubham; Avallone, Francesco; Brandetti, Livia; Wright, Nigel; Ianakiev, Anton
    This study investigates the impact of struts and a central tower on the aerodynamics and aeroacoustics of Darrieus Vertical Axis Wind Turbines (VAWTs) at chord-based Reynolds numbers of 8.12e4. A 2-bladed H-Darrieus VAWT is used, featuring a 1.5m diameter, a solidity of 0.1 and a blade cross-section of symmetrical NACA 0021. The turbine design is kept simple and straight-bladed which is essential for isolating and analyzing the specific effects of struts and a tower. The high-fidelity Lattice Boltzmann Method (LBM) in PowerFLOW 6-2020 and the mid-fidelity Lifting Line Free Vortex Wake (LLFVW) method in QBlade 2.0 are employed, with the mid-fidelity method providing a faster analytical tool for insights into the turbine performance. Firstly, both the LLFVW (mid-fidelity) and LBM (high-fidelity) methods effectively capture the general trends observed in VAWT power performance. However, the former predicts mean thrust values that are approximately 10% higher, and mean torque values that are approximately 19% higher, in comparison to the latter. Subsequently, the former predicts lower streamwise wake velocities relative to those predicted by the latter. These differences increase in configurations that include struts and a tower (to 30% - 31%). Secondly, the presence of struts and a tower leads to a reduction in both mean power (by 15% to 55%) and thrust (by 3% to 3.6%), with a further small decrease observed when doubling the tower diameter (power and thrust both by 0.5% to 3%). The struts predominantly affect the spanwise distribution of blade loading, while the tower impacts the azimuthal variation of blade loading. Additionally, the addition of struts and a tower reduces low-frequency noise (50-200 Hz) while increasing high-frequency noise (> 300 Hz). The observed decrease in mean blade loading results in reduced low-frequency noise, while the increase in high-frequency noise is ascribed to the increased intensity of BWI/BVI leading to higher unsteady loading fluctuations on blades.
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    Uncertainty propagation and management of mixed uncertainties for multi-fidelity multi-disciplinary analysis of propeller with different blade sweep
    (AIAA, 2024-01-04) Shubham, Shubham; Kipouros, Timoleon; Dash, Siddhant; Ianakiev, Anton
    A study on the uncertainty quantification and propagation in a multi-fidelity, multi-disciplinary framework, focusing on aerodynamics, aeroacoustics, and aeroelasticity in propeller blade design is presented. Employing the Lattice Boltzmann Method (LBM) for high-fidelity simulations and the Lifting Line Free Vortex Wake (LLFVW) and Finite Element Analyses (FEA) for mid-fidelity simulations, the study analyzes a 2-bladed, 0.3m diameter propeller using NACA4412 airfoil cross-section, across nine blade sweep configurations. It investigates the effects of two uncertain parameters: freestream velocity, using Interval analysis, and blade tip offset, using Monte Carlo Simulation. The differential analysis between mid and high-fidelity methods shows an uncertainty range of 13.83% to 30.32% for freestream velocity and 2% to 32.48% for blade tip offset, due to the inclusion of the mid-fidelity method. Using the Halton sampling method, it is demonstrated that the uncertainty in the sweep parameter is propagated differently across various performance metrics of the propeller. A backward sweep tends to increase both the mean (by 5-6 %) and uncertainty (by 2-4 %) in all performance parameters, suggesting a potential enhancement in performance but with increased risk. In contrast, a forward sweep reduces mean performance (by 2-3 %) and uncertainty (by 4-6 %) of all parameters except structural deflection, which shows an increasing trend (by 0.5-2 %). This indicates a more reliable aerodynamic and aeroacoustic performance but potentially less efficient operation and increased risk in structural integrity.
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    Wind speed probabilistic forecast based wind turbine selection and siting for urban environment
    (Institution of Engineering and Technology (IET), 2024-11-16) Sachar, Shivangi; Shubham, Shubham; Doerffer, Piotr; Ianakiev, Anton; Flaszyński, Paweł
    Wind energy being a free source of energy is becoming popular over the past decades and is being studied extensively. Integration of wind turbines is now being expanded to urban and offshore settings in contrast to the conventional wind farms in relatively open areas. The direct installation of wind turbines poses a potential risk, as it may result in financial losses in scenarios characterized by inadequate wind resource availability. Therefore, wind energy availability analysis in such urban environments is a necessity. This research paper presents an in‐depth investigation conducted to predict the exploitable wind energy at four distinct locations within Nottingham, United Kingdom. Subsequently, the most suitable location, Clifton Campus at Nottingham Trent University, is identified where a comprehensive comparative analysis of power generation from eleven different wind turbine models is performed. The findings derived from this analysis suggest that the QR6 wind turbine emerges as the optimal choice for subsequent experimental investigations to be conducted in partnership with Nottingham Trent University. Furthermore, this study explores the selection of an appropriate probability density function for assessing wind potential considering seven different distributions namely, Gamma, Weibull, Rayleigh, Log‐normal, Genextreme, Gumbel, and Normal. Ultimately, the Weibull probability distribution is selected, and various methodologies are employed to estimate its parameters, which are then ranked using statistical assessments.