Large wind turbines face more intricate atmospheric conditions with turbulent coherent structures sized similarly to the rotor diameter, posing loading challenges. The present study assesses twelve distinct wind fields using the Large Eddy Simulations (LES) and International Electrotechnical Commission (IEC) Kaimal model scaled to their LES counterpart. The hub height wind speed in the different cases was set to 8.5 m/s (below-rated), 11.5 m/s (at-rated), and 14.5 m/s (above-rated). In a previous study, it was found that the unscaled IEC model-based wind field is conservative and scaled IEC model-based wind fields were found to yield different loads than upon use of LES-based wind fields in different atmospheric stability conditions. The present study aims to understand these differences. Utilizing Spectral Proper Orthogonal Decomposition (SPOD), the original wind fields were decomposed and reconstructed to study the influence of large and small coherent structures represented by their distinct frequencies. SPOD analysis was complemented by wind field spectral analysis considering atmospheric surface layer height, integral length scales, and co-coherence estimates. Integral length scales in the scaled IEC Kaimal model were found to be half of those in unstable atmosphere LES wind fields. The aero-elastic impact on the IEA 22 MW reference wind turbine with a 280 m rotor diameter was evaluated. The analysis reveals that large coherent structures, particularly low-frequency (≤0.06 Hz) ones, significantly impact wind turbine loads, contingent upon atmospheric stratification. Compared to the scaled IEC Kaimal model wind field, the maximum tower fore–aft bending moment and the maximum blade root flap-wise bending moment were found to be higher, for example, by 10% and 5% respectively in an unstable atmosphere during below-rated wind turbine operation. In the same scenario, standard deviation of the tower fore–aft bending moment was found to be higher by up to 50% while standard deviation of the blade root flap-wise bending moment was found to be lower by up to 25%. These findings underscore the critical importance of accurately modeling atmospheric turbulence and its coherent structures for more reliable design and operation of large wind turbines.

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With the growing trend towards larger wind turbine rotor diameters, the impact of wind shear on rotor performance and loads becomes increasingly significant. Atmospheric stability strongly influences wind shear, leading to higher wind shear under stable atmospheric conditions. In this study, the aeroelastic performance of the IEA 22 MW rotor is assessed under inflow conditions generated by different methods. Inflow conditions were generated using turbulence models specified in the IEC Standards and also by Large Eddy simulations. Standalone OpenFAST simulations were conducted with the respective inflow conditions. It was found that at rated and above-rated wind speeds, the time-averaged wind turbine design loads were higher in stable atmospheric conditions, in comparison to the IEC NTM inflow conditions, while the opposite held for below-rated wind speeds. Specifically, the time-averaged root flapwise bending moment and rotor thrust were found to be higher by up to 7% in stable atmospheres. However, maximum design and fatigue loads were considerably higher in the IEC NTM case due to elevated turbulence levels. Compared to the IEC NTM case, the damage equivalent root flapwise bending moment was found to be 30% to 70% lower in the different scenarios.

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Wind power is one of the fastest-growing renewable energy technologies, with global installed wind-generation capacity having increased by a factor of almost 75 in the past two decades. The wind turbine rotors are increasing in diameter to achieve higher power output which poses various challenges in terms of parameters such as structural costs, logistics, maintenance and manufacturing standardization. Multi Rotor Wind Turbines are one potential betterment to Single Rotor Wind turbines. The aim of this study is to compare the performance of Multi Rotor Wind Turbine to a Single Rotor Wind Turbine using Computational Methodology. A total of 8 Horizontal Axis wind turbines which vary in terms of number of rotors, the rotor diameter and the placement of rotors, have been modelled using SolidWorks®. The flow simulations are carried out on ANSYS Fluent®. It is found that a 4 Rotor configuration with rotors placed in a square formation provides an increase in power output by 35% in comparison to its Single Rotor counterpart. Analysis of wake patterns shows that wake recovery is faster in lesser diameter configurations. The drag force is also found to be low in these configurations, which is beneficial in terms of structural costs and tip losses.@en

The airline industry faces a crisis in the future as consumer demand is increasing, but the environmental effects and depleting resources of kerosene mean that growth is unsustainable. Hydrogen is touted as the leading candidate to replace kerosene, but it needs significant technological and economical endeavors. In such a scenario, cryogenic liquid hydrogen (LH2) is predicted to be the most feasible method of using hydrogen. The major challenge of LH2 as an aircraft fuel is that it requires approximately four times the storage volume of kerosene—due to its lower density. Thus the design of cryogenic storage tanks to handle larger quantities of fuel is becoming increasingly important. But the increase in drag associated with larger storage tanks causes an increase in fuel consumption. Hence, this paper aims to evaluate the aerodynamic performance of different storage configurations and aid in the selection of an economic and efficient storage system. Using an Airbus A321 replica as the base model, we sized internal and external tanks to meet the mission fuel requirements and modelled the composite aircraft on SolidWorks®. Then we carried out flow simulation in ANSYS Fluent® to compute the lift and drag values of each storage configuration. For external tanks, we observed that a novel airfoil cross-section tank had the lowest drag value; it performed better than the capped cylinder tanks. Also external tanks kept below the wing lead to minimal disruption of the airflow. Among the internal configurations, we found that increasing the fuselage length is the most aerodynamically efficient way to store the fuel.@en