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Vertical axis wind turbines are receiving significant attention for offshore siting. In general, offshore wind offers proximity to large populations centers, a vast & more consistent wind resource, and a scale-up opportunity, to name a few beneficial characteristics. On the other hand, offshore wind suffers from high levelized cost of energy (LCOE)...
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ARTICLE scitation.org/journal/adv A comparison of two dynamic power cable configurations for a floating offshore wind turbine in shallow water ABSTRACT For the study of the double wave configuration for the dynamic power cable of a Floating Offshore Wind Turbine (FOWT) in shallow water, this paper presented a comparison of the hydrostatic and hydro...
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... Several studies [174,175] have highlighted the possibility of significant reductions in LCOE compared to HAWTs; however, as reported in [173], the LCOE range varies from 274 to 110 $/MWh, based on the maturity of the technology used. Consequently, the technological development and growth of the TRL are crucial to decrease investment costs. ...
Among the primary uses of Vertical Axis Wind Turbines (VAWTs) are small-scale applications, such as electricity generation in urban areas or isolated contexts, which are not grid-connected. However, a promising field of application for VAWTs to be investigated concerns floating offshore applications, where the more
consolidated technologies based on HAWTs face significant challenges due to the harsh environment. The purpose of this study is to review the main floating VAWT concepts developed over the last few years and those currently under development, focusing on the projects and analysing the experimental prototypes and small-scale demonstrators. The main advantages of VAWTs compared to HAWTs are elaborated and presented: among the main ones is the more cost-effective maintenance due to the arrangement of the rotor nacelle assembly at the base of the VAWT, the increased static stability, which allows to reduce the mass of the floating foundation or to support a larger turbine, the reduced aerodynamic losses which allow turbines to be installed closer together and require a small installation area. A particular focus is made on the most urgent needs that demand to be addressed for the development of VAWTs, like the lack of experimental data and the installation of a multi-MW demonstrator to corroborate the technology reliability and challenges, such as the power upscale, the fatigue damage and mooring lines loads. Among the possible floating applications investigated is the energy supply for small isolated islands or offshore installations, like oil and gas platforms or fish farms.
... 2023, 59, 56 2 of 10 platforms. The blade and rotor parameters were analyzed to understand their influence on wind power efficiency using different FEA simulation tools [5][6][7][8]. ...
... based on Antarctic and offshore deep-water moving platforms. The blade and rotor parameters were analyzed to understand their influence on wind power efficiency using different FEA simulation tools [5][6][7][8]. ...
... Wind energy is rapidly developing worldwide due to its nonpolluting and renewable advantages, making it an important clean energy source [1]. As one of the mainstream devices for wind energy utilization, Vertical-Axis Wind Turbine (VAWT) is a device of choice for wind energy extraction in marine and urban areas [2]. VAWT is made of a simple structure and has advantages of scalability, more ecofriendliness, and low manufacturing and maintenance costs compared to Horizontal-Axis Wind Turbine (HAWT). ...
The power efficiency of Darrieus wind turbines significantly deteriorates during rotation caused by periodic dynamic stall at low tip speed ratios. This leads to a strong fluctuation in torque and a reduction in energy acquisition. This paper aims to improve the aerodynamic performance of an H-type Darrieus wind turbine using an innovative fluidic flow control technique based on the synergistic effect of blowing and suction. The aeroacoustic noise emissions accomplished with this enhancement are evaluated. The Improved Delayed Detached Eddy Simulation turbulence model and the Ffowcs Williams-Hawkings acoustic analogy method are adopted to simulate the instantaneous flow field and predict the far field noise. Following validation of the numerical approach using wind tunnel experimental data on a static airfoil, an orthogonal experimental design method was used to analyze and optimize the operating factors. The factors include suction position relative to leading-edge (Ls), blowing position relative to trailing-edge (Lb) and jet coefficient (Cμ). The results indicate that Cμ plays crucial role in determining the airfoil performance, while the role of Lb is almost negligible. Furthermore, the impact of optimal combination of these factors was analyzed based on three different control strategies. It is found that appropriate application of the active control solution can eliminate the wind turbine’s negative torque, avoid excessive alternating load on the rotor and improve the energy extraction efficiency. The aeroacoustic noise estimation shows that the active device can reduce the noise emission by moderating pressure fluctuation, stabilizing the flow field and influencing the vortex shedding. Similarly, the proposed active control solution can reduce the wind turbine noise level by up to 6.56 dB by modifying the sound pressure spectra at frequencies between 100 and 1000 Hz.
... As wind energy is moving to deployments in deeper waters offshore, maintenance and installation procedures as well as cost trends are changing. It has also been shown that floating VAWTs have the potential to achieve a significant reduction in the cost of energy (COE) compared to floating HAWTs (Shelley et al., 2018;Griffith et al., 2016) and mitigate aero-elastic effects like flutter (Ahsan et al., 2022). In addition, floating VAWTs are much more suitable in wind farm conditions due to quicker dissipation of wakes when placed in counter-rotating pairs (Kinzel et al., 2012). ...
A good understanding of aerodynamic loading is essential in the design of vertical-axis wind turbines (VAWTs) to properly capture design loads and to estimate the power production. This paper presents a comprehensive aerodynamic design study for a 5 MW Darrieus offshore VAWT in the context of multi-megawatt floating VAWTs. This study systematically analyzes the effect of different, important design variables including the number of blades, aspect ratio and blade tapering in a comprehensive load analysis of both the parked and operating aerodynamic loads including turbine power performance analysis. The number of blades is studied for two- and three-bladed turbines, aspect ratio is defined as ratio of rotor height and rotor diameter and studied for values from 0.5 to 1.5, and blade tapering is applied by means of adding solidity to the blades towards blade root ends, which affects aerodynamic and structural performance. Analyses were carried out using a three-dimensional vortex model named CACTUS (Code for Axial and Cross-flow TUrbine Simulation) to evaluate both instantaneous azimuthal parameters as well as integral parameters, such as loads (thrust force, lateral force and torque loading) and power. Parked loading is a major concern for VAWTs; thus, this work presents a broad evaluation of parked loads for the design variables noted above. This study also illustrates that during the operation of a turbine, lateral loads are on par with thrust loads, which will significantly affect the structural sizing of rotor and platform and mooring components.
... Research on offshore wind energy has shown an upward trend due to the availability of a better and more consistent wind resource. In an offshore context, VAWTs (vertical axis wind turbines) require smaller, cheaper floating platforms compared to that needed for HAWTs (horizontal axis wind turbines) [1,2]. This is illustrated in Fig. 1, where for HAWTs the drivetrain and generator are placed high above the water, a huge overturning moment is created that the floating platform has to stabilize, typically by adding mass to the substructure. ...
Floating platforms provide vertical axis wind turbines (VAWTs) significant advantages over offshore horizontal axis wind turbines, which has led to increased research interest in offshore VAWT technology. This paper examines dynamic stability of floating VAWTs and presents structural dynamic and aero-elastic flutter analysis of utility-scale 5 MW floating VAWTs by coupling a rotor finite element model with a linearized model for the floating system. The coupled floating VAWT model is utilized to study the effects of tower height, number of blades, blade tapering scheme, and impacts of the floating platform on modal properties and flutter. The study provides important new results and guidance to floating VAWT designers: (1) tower height increase leads to lower tower frequencies more prone to resonance, (2) by moving from land-based foundations to a floating TLP foundation, tower-mode frequency is increased significantly (by 49%–68%) which mitigates resonance and increases the flutter RPM (154% increase), (3) increasing the number of blades reduces the tower mode frequencies for both land-based and floating configuration, and (4) blade chord tapering can have a significant impact on increasing the tower mode flutter RPM. Further, analysis of low-frequency rigid body modes shows a safe, higher flutter RPM relative to the operating RPM.
... This causes the maintenance to be easier and to lower the centre of gravity. This is beneficial for floating applications [42]. However, VAWTs tend to operate at lower tip speed ratios, resulting in larger torque, impacting the drive train. ...
... One can note that the WindQuest design shows higher optimal TSR and operates 1 to 3 RPM higher than usual VAWT designs, such as those presented in [23,24]. This design choice takes into consideration technical and economic considerations [1]. ...
... Moreover, the excitation from the 1P and 2P frequencies generated by the rotor would have less impact over the sub-structure. This observation illustrates the strong influence of the VAWT design on the floater's response, thus correlating with the concussions from [24]. ...
This article describes the experimental comparison of the DTU 10MW HAWT with the WindQuest 10MW VAWT scaled models when both fitted on the Nautilus-10 semi-submersible. For the campaign in Ifremer Wind&Wave tank, different rotor representations are tested from inertia only to hybrid testing with propellers and a Software in the Loop. The hybrid testing uses a tabulated approach for thrust computation and is discussed in this article. The different thrust reproduction methods are compared to OpenFAST simulations calibrated during the Lifes50+ project and used as reference points. When quantifying the scale model’s fidelity to Open Fast, cross-correlation was increased up to 14% with the use of the SiL. Thanks to the validation of hydrodynamic simulations based on experimental responses of the floater, it is shown that the VAWT rotor can be upscaled to 13MW for the same platform.
... (VAWTs) has surged [1]. Much of the research focuses on offshore applications [2] or urban-scale implementation [3] arising from well-known advantages such as insensitivity to the wind direction [4] and the ground-or water-level location of the generator. Furthermore, symmetric and uniform blade profiles along the span can significantly reduce manufacturing costs. ...
Dynamic stall is exploited to produce positive torque on a large-chord/radius-ratio (c∕R) vertical-axis wind turbine. An elementary kinematic analysis shows that the blades experience large variations in angle of attack that produce deep dynamic stall, combined with large relative dynamic pressure variations, that are phase shifted by approximately 90 deg. The phase shift allows dynamic lift-overshoot effects associated with the formation of a dynamic stall vortex to drive the turbine when the relative dynamic pressure is high, whereas lift stall associated with shedding of the vortex occurs when the relative dynamic pressure is low. Blades also experience variable virtual camber (or "virtual morphing") effects and favorable chordwise pressure gradients, where the former produces a virtual leading-edge droop that reduces the leading-edge angle of attack. Open jet wind-tunnel tests of a two-bladed model turbine revealed maximum power coefficients of 16% that were almost independent of c∕R. Flow visualization confirmed that dynamic stall, with the associated dynamic stall vortex, is the mechanism that drives the turbine to maximum power. Until reliable design tools are developed, either empiricism combined with dimensional analysis or high-fidelity computational fluid dynamics are proposed for optimization and analysis.
... With the offshore wind industry moving towards larger turbines and deeper waters, the potential for floating vertical axis wind turbines (VAWT) is increasing. First of all, the VAWT can probably be scaled to larger turbine sizes more easily than the horizontal axis wind turbine (HAWT) [1]. Secondly, the VAWT is very well suited for application on a floating support structure. ...
A semi-submersible Tri-Floater has been designed to support a 6 MW vertical axis wind turbine (VAWT) with active blade pitch control. Due to the low centre of gravity and large allowable floater tilt angle, a relatively small floater can be used to support a VAWT. Coupled simulations including hydrodynamics, mooring system, aerodynamics and control system have been performed to analyse the strongly coupled dynamics of floater and wind turbine. Software tools have been developed or upgraded to enable these simulations. Based on typical extreme operational and survival design load cases, it is illustrated that the active blade pitch control system can be successfully used to minimize the governing loads on the floater. Whereas for a VAWT with fixed blades, the parked survival conditions are typically design driving for the floating support structure, this is not the case if blade pitch control is applied. It is concluded that, compared to a horizontal axis wind turbine (HAWT) with the same rated power, a 20 percent lighter floater can be used as support structure for the VAWT with active blade pitch control.
... ine (HAWT) of the type extensively used for wind farms and a Vertical Axis Wind Turbine (VAWT). Although only a few large VAWT prototypes have been evaluated and most power production units are of a much smaller scale than HAWTs, a preliminary 5 MW VAWT design for offshore work has been developed by Sandia National Laboratory (Fowler, et. al, 2011;Griffith et. al, 2016). For this study, both turbine units are rated at 5 MW capacity and the Y-Wind semi-submersible foundation, developed by VL Offshore (VLO), is sized for each configuration. Along with turbine and floating foundation data various other appropriate input parameters are used to calculate the LCoE values for the two configurations and then c ...
... HAWTs are being considered for future offshore floating wind farms. Commercial scale VAWT turbines exist only up to a few hundred KW ratings, though engineering designs up to 1 and 2MW are begin considered by some European firms, and Sandia National Laboratory (SNL) has developed its preliminary 5 MW VAWT design for offshore (Fowler, et. al, 2011;Griffith et. al, 2016). ...
The technology to engineer, fabricate and install offshore floating wind turbine exists and is feasible for all components. Applying lessons learned from offshore oil and gas projects with respect to engineering execution options, competitive supply and reduction in life cycle costs makes offshore floating wind a commercially viable energy supply in regions with relatively high electricity prices or in regions that have other geographical or resource constraints to bringing additional energy supply on-line.
However, while horizontal wind turbine (HAWT) technology is developing rapidly and driving down cost, it may be possible to further drive down offshore floating wind costs by choosing a vertical axis wind turbine (VAWT) technology. VL Offshore has developed a cost effective 5 MW floating foundation, Y-Wind semi for HAWT. In this study, the LCoE (Levelized Cost of Energy) of the Y-Wind semi with 5 MW HAWT is compared against the same foundation type with a 5 MW VAWT. For the present work, a 200 MW wind farm, located about 10km off shore the Northeast U.S. at a water depth of 100m is selected. This water depth exceeds the current commercial limits for fixed foundations for offshore wind. LCoE is estimated using the tool developed by NREL, considering all the cost parameters of foundation and mooring CAPEX, installation, operation and maintenances, in-field and export power cables, capacity factors, turbine layouts, substation, discount rate, cost escalation rate, current electricity price and design life. The LCoE results indicate that a 5 MW VAWT foundation will be more commercially viable than a comparable 5 MW HAWT foundation. The LCoE values compare favorably to the LCoE values for most electricity prices in the Northeast states.
