Noise pollution is known as the biggest environmental problem of the Horizontal axis wind turbines. The main part of the noise is in the range of Low-Frequency Noise (LFN), since wind turbines rotate slowly. Several studies have shown that LFN could have adverse effects on the human health. In this work, LFN generated by the NREL VI wind turbine in wind speeds of 13 m/s is calculated using a hybrid approach. In this approach, the noise sources are defined on a data surface (DS), and then the noise propagating form DS is calculated. The results obtained show that a DS obtained by scaling the blade span with a size factor of 5 is appropriate for surrounding all the main sources in this problem. It means that in addition to the sources located on the blade surface, a significant part of the steady sources generating LFN is far from the blades. On the other hand, the results obtained show that the tip vortices have no significant effect on LFN.

Development of wind energy is gaining a great interest nowadays with over 25% annual growth in any configurations and sizes. Designing a wind turbine with improved performance remains the ultimate research and development goal. Therefore, understanding the influence of the different wind turbine key parameters, e.g., tip speed ratio (TSR), twist and pitch angles, number of blades, and airfoil chord distribution, is critical. In this work, an improved blade element model (BEM) is developed by correcting the code with tip loss, Buhl empirical correction, skewed wake, and rotational effect. These corrections are necessary to extend the application of the method to the turbulent wake regime for the Horizontal axis wind turbine (HAWT) configuration. Results from the developed code are compared with the NREL measured data of the two-bladed Unsteady Aerodynamics Experiment (UAE) phase-VI turbine. They indicate an improved trend with the incorporation of these corrections. The performance of the three-bladed 3.5-kW HAWT was tested and found to follow closely the experimental trend. As the mismatch between these low fidelity analyses (BEM) and the experimental work persists, the undertaken analysis demonstrates its limitation, and it emphasizes the role of high fidelity wind tunnel and flow simulations. BEM analysis, however, shows that designing blades with proper twist and pitch angles, and targeting suitable TSR could lead to substantial gain (over 10%) in the performance.

This article introduces a novel Induction Blade (IB) prototype modeled by Blade Element Momentum (BEM) theory, which develops higher torque during the starting phase for Horizontal axis Wind turbines (HAWT), especially for micro-turbines. The IB is composed of two parallel blades joined at their tips and roots, forming a distinctive hole in the space between the blades that generates a Venturi effect as air passes through. This phenomenon in the IB hole together with the extra lift generated by the area of the second blade produce extra valuable torque during the starting phase. We used Computational Fluid Dynamics (CFD) analysis to evaluate the aerodynamic properties of this design compared with a traditional blade design of the same radius. The IB and traditional prototypes were built (50W, diameter 0. 62m, λ=9 and at speed rated 8m/s) by additive manufacturing in a 3D printer and their aerodynamic behaviors tested in a small wind tunnel (square section 0. 7m x 0. 7m). Our results using CFD analysis show that this novel IB produces up to 65% extra torque without losing output power for low wind velocity (5-8 m/s). IMPI (Mexican Institute of Industrial Protection) protects this prototype shape.

The development of models that predict power production of wind farms (WFs) by considering the interacting wakes is important; because wakes of the turbines exert a significant influence on power production of turbines, and hence on the layout of wind turbines in WFs. Thus, the purpose of present study was to provide an innovative analytical method for the prediction of power generation of the WFs that have a flat terrain and are consisted of Horizontal-axis wind turbines (HAWTs) with the same hub height. The methodology employed utilized an analytical Gaussian model of HAWT wake to develop an analytical model that calculates the effective wind velocity acting on the downstream HAWT(s), which is further used for reading its generated power from the turbine’s catalog; thus, providing the generated power of the WF as the output. The results of presented model were validated by the field measurements data of Horns Rev WF and also were compared to two analytical models for predicting the generated power. The results were compared with two numerical simulations of the literature, and the output data of three commercial software. Moreover, the error analysis revealed that the presented model mostly showed superior accuracy in predicting the field measurements data.

In the present situation and considering the dangers that affect human life and the environment, it is necessary to expand the use of renewable energy that is available in all geographical areas. Environmental pollution caused by urban life has attracted researchers attention to the use of renewable energy such as vertical axis wind turbines (VAWTs) with the aim of urban application. Because of their unique features, these turbines can provide the electricity needed for the targets, but to date, less attention has been paid to their tower structure. A wind turbine tower is one of the main and costliest components of wind systems. In this paper, based on the standards of turbine design and its structure, an algorithm was presented to create more resistance and strength in the tower structure and control the tower's deflection caused by incoming loads. Different models of simple monopole tower, variable cross-section monopole tower, monopole tower with channel beam control, and monopole tower with lateral restraint in the case study of Iran were simulated. Results show that models with lateral restraint have the lowest deflection of about 3 to 5 cm and, in addition to passing all design standards, the members' stress ratio is allowed within the limit.

Multi-Megawatt wind turbines have long, slender, and heavy blades that can undergo extreme wind loadings. The aero-elastic stability of wind turbine blades is of great importance in both the power production and the load carrying capacity of structure. This paper investigates the aero-elastic stability of wind turbine blades modeled as thin-walled composite box beam utilizing unsteady incompressible aerodynamics. The structural model incorporates a number of non-classical effects such as the transverse shear, warping inhibition, nonuniform torsional model, and rotary inertia. The unsteady incompressible aerodynamics based on the Wagner’ s function is used in order to determine the aerodynamic loads. The governing differential equations of motion are obtained using the Hamilton’ s principle, and solved using the extended Galerkin’ s method. The results obtained are related to clarification of the effects of angular velocity and wind speed on the aeroelastic instability boundaries of the thin-walled composite beams. The results are expected to be useful toward obtaining better predictions of the aero-elastic behavior of composite rotating blades.