A coupled hydro-structural design optimization for hydrokinetic turbines

Kolekar, Nitin; Banerjee, Arindam

doi:10.1063/1.4826882

Cited by 27 publications

(10 citation statements)

References 46 publications

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“…The mesh used for our current study is shown in Figure 2. Our previous CFD simulations [26,29] on the same model turbine demonstrated Reynolds number (based on turbine diameter) converges 2.04×10 5 ; a uniform inlet flow speed of 0.73 m/s was thus chosen for analysis and cross-comparison with previous work [26]. The channel outlet was specified as an outlet boundary condition with the average relative pressure of zero.…”

Section: A Domain and Turbine Model Descriptionmentioning

confidence: 99%

“…Reynolds-averaged Navier-stokes equations with κ-ω SST turbulence model with curvature correction (CC) was solved [30,31]. A multiple reference frame technique is adopted similar to our previous studies [26,29]; a rotation frame (in our case, the inner fluid domain) takes into account the effect of turbine rotation by transforming an unsteady flow in inertial frame (stationary) to a steady flow in non-inertial frame (rotating). The mass and momentum conservation equations can be written as…”

Section: B Governing Equations and Non-dimensional Parametersmentioning

confidence: 99%

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Performance and wake characteristics of a tidal turbine under yaw

Modali¹,

Kolekar²,

Banerjee³

2018

Int. J. Mar. Ene.

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In tidal streams and rivers, the flow of water can be at yaw to the turbine rotor plane causing performance degradation and a skewed downstream wake. The current study aims to quantify the performance variation and associated wake behavior caused by a tidal turbine operating in a yawed inflow environment. A three-dimensional computational fluid dynamics study was carried out using multiple reference frame approach using κ-ω SST turbulence model with curvature correction. The computations were validated by comparison with experimental results on a 1:20 scale prototype for a 0° yaw case performed in a laboratory flume. The simulations were performed using a three-bladed, constant chord, untwisted tidal turbine operating at uniform inflow. Yaw effects were observed for angles ranging from 5° to 15°. An increase in yaw over this range caused a power coefficient deficit of 26% and a thrust coefficient deficit of about 8% at a tip speed ratio of 5 that corresponds to the maximum power coefficient for the tested turbine. In addition, wake propagation was studied up to a downstream distance of ten rotor radius, and skewness in the wake, proportional to yaw angle was observed. At higher yaw angles, the flow around the turbine rotor was found to cushion the tip vortices, accelerating the interaction between the tip vortices and the skewed wake, thereby facilitating a faster wake recovery. The center of the wake was tracked using a center of mass technique. The center of wake analysis was used to better quantify the deviation of the wake with increasing yaw angle. It was observed that with an increase in yaw angle, the recovery distance moved closer to the rotor plane. The wake was noticed to meander around the turbine centerline with increasing downstream distance and slightly deviate towards the free surface above the turbine centerline, magnitude of which varied depending on yaw.

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Section: A Domain and Turbine Model Descriptionmentioning

confidence: 99%

Section: B Governing Equations and Non-dimensional Parametersmentioning

confidence: 99%

Performance and wake characteristics of a tidal turbine under yaw

Modali¹,

Kolekar²,

Banerjee³

2018

Int. J. Mar. Ene.

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“…A moving reference frame was, therefore, incorporated to take the blade rotation into account and transform the unsteady flow in an inertial (stationary) frame to a steady flow in the non-inertial (moving) frame. When a moving reference frame is activated, the equations of motions are modified to incorporate the additional acceleration terms which occur due to the transformation from the stationary to the moving reference frame [23][24][25]. Solving these equations in a steady state manner, the flow around the moving parts can be modeled.…”

Section: Governing Equationsmentioning

confidence: 99%

“…The molecular viscosity (µ ef f ) is the sum of the dynamic viscosity (µ) and turbulent viscosity (µ t ); being calculated from a representative turbulence model. Among different turbulence models existing in the literature, the k − ω shear stress transport (SST) model was chosen for the analysis due to its capability of providing accurate flow-field predictions under adverse pressure gradient and separated flow conditions, both, conditions considered as prevalent in hydrokinetic turbine performance [23,[26][27][28][29].…”

Section: Governing Equationsmentioning

confidence: 99%

Experimental Investigations and CFD Simulations of the Blade Section Pitch Angle Effect on the Performance of a Horizontal-Axis Hydrokinetic Turbine

Chica

Cardona-Mancilla

Slayton

et al. 2018

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Three twisted blades of a 1 kW prototype hydrokinetic turbine were designed based on the Blade Element Momentum (BEM) theory with a tip speed ratio of 6.25; a water velocity of 1.5 m/s; an angle of attack and pitch angle of 5 and 0 • , respectively; a power coefficient of 0.4382 and a drive train efficiency of 70%. S822 hydrofoil was used to generate the coordinates of the blade cross-section. Experimental investigations and Computational Fluid Dynamics (CFD) simulations were carried out to estimate the performance of the blade design and know the effect of the section pitch angle on the performance of a horizontal-axis hydrokinetic turbine. The obtained results showed that the increase in the section pitch angle enhanced the performance up to a certain value. Further increase in the section pitch angle resulted in a low performance and a reduction of the rotation velocity, which in turn requires a high gearing ratio of the transmission system.

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“…The benefits of multiblades rotors (more than three blades) relative to axial flows is that they have self‐starting capabilities , and offers a better power‐dimensions ratio. These benefits, combined with the profile S1223 hydrofoil, have allowed us to conduct an investigation of various rotors with different numbers of blades.…”

Section: Hydrofoil and Rotormentioning

confidence: 99%