Search results

Wind energy has become a distinguished field of energy among the alternative energy resources. Despite economical disadvantages, the production of wind energy is desired to fulfill the demand of the energy. Low reliability is a big issue in the development of wind energy technology that has affected wind farm operations. The purpose of the study is to find the reason for the low reliability and high downtime for wind turbines.

The systems engineering approach has a high success rate in handling complex systems such as wind farms. A failure finding model is presented based on the systems engineering, with the focus to analyze the failures at the interfaces. The required data have been collected by reviewing the literature.

Gear box interfaces are a vital reason for the higher downtime and frequent failures of wind turbines, and the bearing and the lubricant in the gear box are affected because of their inappropriate combination.

The reliability and the maintainability of the wind turbine is a topic of major importance. The study is an attempt to contribute to a more sophisticated solution to the reliability problem of the wind turbine. Moreover, it shows the importance of interfaces in designing the complex systems.

One of the most significant challenges facing contemporary architectural and urban design is how it can become more sustainable. Energy consumption by housing is a major source of greenhouse gas emissions and a cause of depletion of non-renewable energy sources. Of particular concern is existing stock, which has the worst performance and is hardest to improve.

One means of addressing these issues that is attracting increasing interest is the integration of embedded renewable energy technologies. This paper discusses the use of wind turbines on buildings as a response to climate change legislation. It examines the potential for embedded generation in a specific built form (existing high rise housing) and places this in the context of a particular geographical location (Glasgow, Scotland) where the existing provision is highly problematic, but which also presents significant potential. It describes findings from two projects in Glasgow, a pilot installation on a city centre multi-storey block, and subsequent feasibility study for a Housing Association managed multi-storey block and identifies the problems and opportunities that may be applied in similar projects elsewhere.

Wind turbines are of growing importance for the production of renewable energy. The kinetic energy of the blowing air induces a rotary motion and is thus converted into electricity. From the mechanical point of view the complex dynamics of wind turbines become a matter of interest for structural optimization and optimal control in order to improve stability and energy efficiency. The purpose of this paper therefore is to present a mechanical model of a three‐blade wind turbine with a momentum and energy conserving time integration of the system.

The authors present a mechanical model based upon a rotationless formulation of rigid body dynamics coupled with flexible components. The resulting set of differential‐algebraic equations will be solved by using energy‐consistent time‐stepping schemes. Rigid and orthotropic‐elastic body models of a wind turbine show the robustness and accuracy of these schemes for the relevant problem.

Numerical studies prove that physically consistent time‐stepping schemes provide reliable results, especially for hybrid wind turbine models.

The application of energy‐consistent methods for time discretization is intended to provide computational robustness and to reduce the computational costs of the dynamical wind turbine systems. The model is aimed to give a first access into the investigation of fluid‐structure interaction for wind turbines.

The purpose of this paper is to examine the aerodynamical and air mass flow phenomena taking place in the channel of a modified version of one of the well-known Sistan wind mills, in order to improve its aerodynamic performance.

The simulations are done by means of the finite volume method associated to the realizable k-ε turbulence model. The computational domain consists in a rotating sub domain including the wind turbine equipped with nine blades and a fixed sub domain including the rest of the computational domain. Both are connected by means of a sliding mesh interface. Calculations are done for 8×105-4×106 Reynolds number range, corresponding to inlet velocities varying from 2 to 10 m s−1.

The velocity fields are presented for the stopped and operating turbine (static and dynamic conditions). A careful examination of the aerodynamic phenomena is performed to detect potential vortices that could develop in the central cavity of the active assembly, and then influence the wind turbine’s operation.

The modification proposed in this survey is easy to realize, consisting in covering the top of the entire original assembly that avoids the extraction of a large part of the air mass flow occurring through the open top of the original version. The aerodynamic phenomena occurring across the channel of this large vertical axis wind turbine are substantially different from those of the original version.

To make wind energy (one of the alternative-energy production technologies) economical, wind-turbines (convertors of wind energy into electrical energy) are required to operate, with only regular maintenance, for at least 20 years. However, some key wind-turbine components (especially the gear-box) often require significant repair or replacement after only three to five years in service. This causes an increase in both the wind-energy cost and the cost of ownership of the wind turbine. The paper aims to discuss these issues.

To overcome this problem, root causes of the gear-box premature failure are currently being investigated using mainly laboratory and field-test experimental approaches. As demonstrated in many industrial sectors (e.g. automotive, aerospace, etc.) advanced computational engineering methods and tools cannot only complement these experimental approaches but also provide additional insight into the problem at hand (and do so with a substantially shorter turn-around time). The present work demonstrates the use of a multi-length-scale computational approach which couples large-scale wind/rotor interactions with a gear-box dynamic response, enabling accurate determination of kinematics and kinetics within the gear-box bearings (the components most often responsible for the gear-box premature failure) and ultimately the structural response (including damage and failure) of the roller-bearing components (e.g. inner raceways).

It has been demonstrated that through the application of this approach, one can predict the expected life of the most failure-prone horizontal axis wind turbine gear-box bearing elements.

To the authors’ knowledge, the present work is the first multi-length-scale study of bearing failure in wind-turbines.

Wind turbines are one of the best candidates to solve the problem of increasing energy demand in the world. The aim of this paper is to apply a multi-objective structural optimization study to a Phase II wind turbine blade produced by the National Renewable Energy Laboratory to obtain a more efficient small-scale wind turbine.

To solve this structural optimization problem, a new Non-Dominated Sorting Genetic Algorithm (NSGA-II) was performed. In the optimization study, the objective function was on minimization of mass and cost of the blade, and design parameters were composite material type and spar cap layer number. Design constraints were deformation, strain, stress, natural frequency and failure criteria. ANSYS Composite PrepPost (ACP) module was used to model the composite materials of the blade. Moreover, fluid–structure interaction (FSI) model in ANSYS was used to carry out flow and structural analysis on the blade.

As a result, a new original blade was designed using the multi-objective structural optimization study which has been adapted for aerodynamic optimization, the NSGA-II algorithm and FSI. The mass of three selected optimized blades using carbon composite decreased as much as 6.6%, 11.9% and 14.3%, respectively, while their costs increased by 23.1%, 29.9% and 38.3%. This multi-objective structural optimization-based study indicates that the composite configuration of the blade could be altered to reach the desired weight and cost for production.

ACP module is a novel and advanced composite modeling technique. This study is a novel study to present the NSGA-II algorithm, which has been adapted for aerodynamic optimization, together with the FSI. Unlike other studies, complex composite layup, fiber directions and layer orientations were defined by using the ACP module, and the composite blade analyzed both aerodynamic pressure and structural design using ACP and FSI modules together.

The objective of this paper to assess the wind energy potential of the Sujawal site for minimizing the dependence on fossil fuels.

The site-specific wind shear coefficient and the turbulence model were investigated. The two-parameter, k and c, Weibull distribution function was used to analyze the wind speed of the Sujawal site. The standard deviation of the site was also assessed for a period of a year. Also, the coefficient of variation was carried out to determine the difference at each height. The wind power and energy densities were assessed for a period of a year. The economic assessment of energy/kWh was investigated for selection of appropriate wind turbine.

The mean wind shear of the Sujawal site was found to be 0.274. The mean wind speed was found to be 7.458, 6.911, 6.438 and 5.347 at 80, 60, 40 and 20 m, respectively, above the ground level (AGL). The mean values of k parameter were observed to be 2.302, 2.767, 3.026 and 3.105 at 20, 40, 60 and 80 m, respectively, for a period of a year. The Weibull c m/s parameter values were found to be 8.415, 7.797, 7.265 and 6.084 m/s at 80, 60, 40 and 20 m, respectively. The mean values of standard deviation were found to be 0.765, 0.737, 0.681 and 0.650 at 20, 40, 60, and 80 m, respectively. The mean wind power density (W/m²) was found to be 287.33, 357.16, 405.16 and 659.58 for 20, 40, 60 and 80 m, respectively. The economic assessment showed that wind turbine 7 had the minimum cost/kWh US$ 0.0298.

The Sujawal site is suitable for installing the utility wind turbines for energy generation at the lowest cost; hence, a sustainable solution.

Pakistan is an energy starving country that needs continuous supply of energy to keep up its economic speed. The aim of this paper is to assess the wind resource and energy potential of Quaidabad site for minimizing the dependence on fuels and improving the environment.

The Quaidabad site wind shear coefficient and turbulence intensity factor are investigated. The two-parameter k and c Weibull distribution function is used to analyze the wind speed of site. The standard deviation of the site is also assessed for a period of a year. The wind power density and energy density are assessed for a period of a year. The economic assessment of energy/kWh is investigated for selection of appropriate wind turbine.

The mean wind shear coefficient was observed to be 0.2719, 0.2191 and 0.1698 at 20, 40 and 60 m, respectively, for a period of a year. The mean wind speed is found to be 2.961, 3.563, 3.907 and 4.099 m/s at 20, 40, 60 and 80 m, respectively. The mean values of k parameters were observed to be 1.563, 2.092, 2.434 and 2.576 at 20, 40, 60 and 80 m, respectively, for a period of a year. The mean values of c m/s parameter were found to be 3.341, 4.020, 4.408 and 4.625 m/s at 20, 40, 60 and 80 m, respectively, for a period of a year. The major portion of values of standard deviation was found to be in between 0.1 and 2.00 at 20, 40, 60 and 80 m. The wind power density (W/m²) sum total values were observed to be 351, 597, 792 and 923 W/m² at 20, 40, 60 and 80 m, respectively, for a period of a year. The mean coefficient of variation was found to be 0.161, 0.130, 0.115 and 0.105 at 20, 40, 60 and 80 m, respectively. The sum total energy density was observed to be 1,157, 2,156, 2,970 and 3,778 kWh/m² at 20, 40, 60 and 80 m, respectively. The economic assessment is showing that wind turbine E has the minimum cost US$0.049/kWh.

The Quaidabad site is suitable for installing the utility wind turbines for energy generation at the lowest cost.

The purpose of this paper is to assess the wind resource and energy potential of the Sanghar site for minimizing the dependence on fossil fuels and improving the environment.

The Sanghar site wind shear coefficient and turbulence intensity factor are investigated for a period of a year. The two-parameter k and c Weibull distribution function is used to analyze the wind speed of the Sanghar site. The standard deviation, coefficient of variation, wind power density and energy density; and capacity factor was assessed for a period of a year. The economic assessment of energy/kWh is investigated for the selection of appropriate wind turbines.

The mean wind shear of the Sanghar site was found to be 0.2509. The mean wind speed was found to be 4.766, 5.534 and 6.121 at 20, 40 and 60 m above the ground level. The mean value of the k parameter was observed to be 2.433, 2.777 and 2.862 at 20, 40 and 60 m for a period of a year. The Weibull c m/s parameter was found to be 5.377, 6.245 and 6.906 m/s at 20, 40 and 60 m. The major portion of values of standard deviation was found to be in between 0.1 to 2.00 at 20, 40 and 60 m. The mean wind power density values were observed to be 88.33, 93.5 and 110.16 W/m2 at 20, 40 and 60 m; respectively, for a period of a year. The mean coefficient of variation was found to be 0.1478, 0.1205 and 0.1033 at 20, 40 and 60 m; respectively. The mean energy density was found to be 476.75, 683.08 and 866.33 kWh/m² at 20, 40 and 60 m; respectively. The mean capacity factor for different wind turbines was ranged between 18 to 24.83 for a period of a year. The economic assessment showed that wind turbine B has the minimum cost (US$) 0.0484/kWh.

The assessment provides the solution to sustainable energy generation which reduces the consumption of fuel and the effect of fluctuating price of fuel in the world market on local consumers.

Wind energy may have social implications including environmentally friendly, consistent supply of energy during the peak summer season, less unit per cost, etc.

The Sanghar site is new and assessed for the first time in this research work. The Sanghar site is suitable for installing utility wind turbines for energy generation at the lowest cost.

Nowadays flaps and winglets are one of the main mechanisms to increase airfoil efficiency. This study aims to investigate the power performance of vertical axis wind turbines (VAWT) that are equipped with diverse gurney flaps. This study could play a crucial role in the design of the VAWT in the future.

In this paper, the two-dimensional computational fluid dynamics simulation is used. The second-order finite volume method is used for the discretization of the governing equations.

The results show that the gurney flap enhances the power coefficient at the low range of tip speed ratio (TSR). When an angled and standard gurney flap case has the same aerodynamic performance, an angled gurney flap case has a lower hinge moment on the junction of airfoil and gurney flap which shows the structural excellence of this case. In all gurney flap cases, the power coefficient increases by an average of 20% at the TSR range of 0.6 to 1.8. The gurney flap cases do not perform well at the high TSR range and the results show a lower amount of power coefficient compare to the clean airfoil.

The angled gurney flap which has the structural advantage and is deployed to the pressure side of the airfoil improves the efficiency of VAWT at the low and medium range of TSR. This study recommends using a controllable gurney flap which could be deployed at a certain amount of TSR.