Optimization of Hydrokinetic Swept Blades

Gemaque, Miriam L. A.; Vaz, Jerson Rogério Pinheiro; Saavedra, Osvaldo R.

doi:10.3390/su142113968

Cited by 6 publications

(7 citation statements)

References 31 publications

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“…Furthermore, its turbine model is on-power operation. The results reported by Gemaque [20] are consistent with this work's conclusion, in which at starting there is no velocity induction at the rotor blades, leading to a no-power extraction condition. Nevertheless, the optimal performance for a sweeping blade angle is 30 degrees for backward-curved blades, and the turbine is in operation.…”

Section: Resultssupporting

confidence: 88%

“…For β = 10 • , the C T values are approximately equal to that of straight blade before the maximum point. These findings indicate that some swept blade may reduce the thrust coefficient under particular operational conditions [20], which contradicts the Kaya [9] conclusions as previously described. Figure 13 displays the thrust coefficient over time for blades with different sweep angles.…”

Section: Resultscontrasting

confidence: 77%

“…The radius of turbine swept blades should be mapped dependent on the radius ratios and the local sweep angle β j , in radians, and may be written as follow [19,20]…”

Section: Blade Element Momentum For Rotors With Swept Bladesmentioning

confidence: 99%

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Quasi-Steady Analysis of a Small Wind Rotor with Swept Blades

et al. 2023

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It is well known that wind power generation addresses the energy needs of small and remote populations as one of the alternatives to petroleum-based energy’s greenhouse effect. Although there are several publications on rotor design and performance analysis, more should be written about the starting of wind turbines, mainly the small ones, where starting can be a big issue. The present paper evaluates the impact of the swept blade angle on the aerodynamic torque, thrust force, and minimal wind speed required to start the operation of a compact horizontal-axis wind turbine. It presents a novel investigation of the influence of swept rotor blades on the starting performance of a turbine drivetrain. The methodology uses the blade element moment theory coupled to Newton’s second law, in which Palmgren’s extended approach is employed. When the proposed methodology is compared to the experimental data available in the literature, it exhibits good agreement. However, when the wind turbine starts to run, the results show that swept blades do not always enhance the torque coefficient or reduce the thrust force as indicated in some scientific papers. For backward-swept blades, the maximum value decreases 4.0%. Similar behavior is found in thrust force for forward-swept blades. Therefore, more study is required to evaluate many blade foils in several operational environments to confirm this statement.

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Section: Resultssupporting

confidence: 88%

Section: Resultscontrasting

confidence: 77%

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Quasi-Steady Analysis of a Small Wind Rotor with Swept Blades

et al. 2023

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“…Those parameters maximize the turbine power coefficient C P . According to [5] and further mentioned in [14], if the angle of attack is higher than the stall angle, Equations ( 1) and ( 2) are not valid as the local drag on the blade becomes considerably high, which is ignored in the potential theory. Thus, it is important to state that the Glauert optimization procedure is only valid for λ > 1.…”

Section: Hydrokinetic Turbine Configurationmentioning

confidence: 99%

Assessment of a Diffuser-Augmented Hydrokinetic Turbine Designed for Harnessing the Flow Energy Downstream of Dams

2023

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Harnessing the remaining energy downstream of dams has recently gained significant attention as the kinetic energy available in the water current is considerable. This work developed a novel study to quantify the energy gain downstream of dams using a horizontal-axis hydrokinetic turbine with a diffuser. The present assessment uses field data from the Tucuruí Dam, where a stream velocity of 2.35 m/s is the velocity at which the highest energy extraction can occur. In this case, a 3-bladed hydrokinetic turbine with a 10 m diameter, shrouded by a flanged conical diffuser, was simulated. Numerical modeling using computational fluid dynamics was carried out using the Reynolds averaged Navier–Stokes formulation with the κ – ω shear stress transport as the turbulence model. The results yield good agreement with experimental and theoretical data available in the literature. Moreover, the turbine power coefficient under the diffuser effect could increase by about 55% for a tip speed ratio of 5.4, and the power output increased by about 1.5 times when compared to the same turbine without a diffuser. Additionally, as there are no hydrokinetic turbines installed downstream of dams in the Amazon region, the present study is relevant as it explores the use of hydrokinetic turbines as an alternative for harnessing the turbined and verted flow from dams. This alternative may help avoid further environmental impacts caused by the need for structural extensions.

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“…But it did not study the cavitation on the diffuser, only on the blade. In [6] a new optimization procedure applied to hydrokinetic turbine swept blades was developed, with the main objective being the design of blades with reduced axial load on the rotor and possible reduction of the cavitation on blade tip. The approach demonstrated good result to reduce cavitation on hydrokinetic blades, however, any study on diffuser under cavitating condition was made.…”

Section: Introductionmentioning

confidence: 99%

Cavitation and structural analysis on a flanged diffuser applied to hydrokinetic turbines

et al. 2022

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Flanged diffuser can improve hydrokinetic turbine efficiency. However, in the current literature it is still not clear if the flange allows the possibility of cavitation on its structure, and whether it can support high pressure variation. This work presents a Computational Fluid Dynamics (CFD) study on the effect of cavitation on a flanged diffuser. The water flow through the diffuser was evaluated using a Reynolds Averaged Navier Stokes approach coupled to the Rayleigh-Plesset model to estimate the vapor production rate. The methodology was applied to a flanged diffuser and results were compared with experimental data from the literature. The minimal depth to avoid cavitation on the flanged diffuser was found. The pressure field obtained on CFD was applied as loading in structural analysis using Finite Element Method. The numerical model presented good agreement with experimental data available in the literature. The results showed that cavitation occurs more intensely at a depth of 1.0 m for the model. This intensity gradually decreases as the depth increases. Cavitation can be present in flanged diffusers, especially in the region inside the shroud, where it can directly impact the flow through the rotor. A good safety factor was obtained in the structural analysis.

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Optimization of Hydrokinetic Swept Blades

Cited by 6 publications

References 31 publications

Quasi-Steady Analysis of a Small Wind Rotor with Swept Blades

Quasi-Steady Analysis of a Small Wind Rotor with Swept Blades

Assessment of a Diffuser-Augmented Hydrokinetic Turbine Designed for Harnessing the Flow Energy Downstream of Dams

Cavitation and structural analysis on a flanged diffuser applied to hydrokinetic turbines

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