Blockage effects on the hydrodynamic performance of a marine cross-flow turbine

Consul, Claudio A; Willden, R.H.J.; McIntosh, S.

doi:10.1098/rsta.2012.0299

Cited by 62 publications

(45 citation statements)

References 4 publications

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“…The surface of the channel is approximated with a rigid lid and the floor and lid of each domain are slip wall boundaries (free surface effects are not considered in this work and have been shown to only be significant at very high levels of flow blockage [23]). A simple uniform velocity profile with water (r¼ 1025 kg/m 3 ) flowing at U ∞ ¼2 m/s is used as the inlet boundary condition for each of the simulations in this study.…”

Section: Computational Setupmentioning

confidence: 99%

The effect of blockage on tidal turbine rotor design and performance

Schluntz

Willden

2015

Renewable Energy

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a b s t r a c tThe performance-enhancing effects of closely packing tidal turbines in single row arrays (tidal fences) are evaluated in this computational study. Infinitely long tidal fences are simulated with a range of lateral rotor spacings using a blade element momentum method embedded in a Reynolds averaged Navier eStokes solver (RANS-BEM).First, a rotor design tool is applied to determine a hydrodynamically optimal rotor design for each lateral spacing. In the RANS-BEM method, the effect of blockage (the ratio of rotor swept area to channel cross-sectional area) on rotor optimization is accounted for. Increased blockage is found to result in increased optimal solidity and decreased optimal pitch. Next, each rotor design is simulated in its design spacing as well as several off-design spacings. The resulting power coefficient is largest when the rotor optimized for the highest blockage case operates in the array with the closest lateral spacing. Further, although a rotor's performance is improved through operation at a blockage higher than its design point, it still exhibits inferior performance relative to a rotor designed for that higher blockage. The results indicate that blockage must be considered in the rotor design process if the optimal rotor efficiency for a given spacing is to be achieved.

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Section: Computational Setupmentioning

confidence: 99%

The effect of blockage on tidal turbine rotor design and performance

Schluntz

Willden

2015

Renewable Energy

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“…These simplifications have been previously shown to have little effect on the numerical result for overall turbine torque, see Ref. [40].…”

Section: Numerical Setupmentioning

confidence: 97%

Numerical investigation of laboratory tested cross-flow tidal turbines and Reynolds number scaling

2016

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a b s t r a c tThe cross-flow, or vertical axis tidal turbine, is a prominent configuration of marine renewable energy device aimed at converting tidal currents into electrical energy. This paper highlights the hydrodynamic limitations of laboratory testing such devices and uses numerical simulation to explore the effect of device scaling. Using a 2D Reynolds-Averaged NaviereStokes (RANS) numerical approach, a single turbine blade is initially modelled and validated against published data. The resultant numerical model is then expanded to emulate an experimental cross-flow tidal turbine designed and tested by the University of Oxford. The simulated turbine achieves a close quantitative match for coefficients of power, torque and thrust, forming the basis of a study exploring the effects of Reynolds number scaling in three alternative operating conditions. It is discovered that the coefficient of power (C P ) increases with Re without a ubiquitous correlation until an Re of~350,000. Above this Re the C P values for all three operation conditions become both proportional and predictable. The study represents a significant contribution to understanding the application of detailed numerical modelling techniques to cross-flow tidal turbines. The findings, with regard to scaling from laboratory data, could reduce uncertainty and development costs for new and existing devices.

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“…Numerous studies have computed vertical axis turbines using numerical low order methods, e.g., Ref. [32][33][34][35][36][37] and only very recently Ferrer [19] has provided results for vertical axis turbines using high order solvers and moving meshes.…”

Section: Numerical Simulations For a One Bladed Vertical Axis Turbinesmentioning

confidence: 99%

A Reduced Order Model to Predict Transient Flows around Straight Bladed Vertical Axis Wind Turbines

Clainche

Ferrer

2018

Energies

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Abstract:We develop a reduced order model to represent the complex flow behaviour around vertical axis wind turbines. First, we simulate vertical axis turbines using an accurate high order discontinuous Galerkin-Fourier Navier-Stokes Large Eddy Simulation solver with sliding meshes and extract flow snapshots in time. Subsequently, we construct a reduced order model based on a high order dynamic mode decomposition approach that selects modes based on flow frequency. We show that only a few modes are necessary to reconstruct the flow behaviour of the original simulation, even for blades rotating in turbulent regimes. Furthermore, we prove that an accurate reduced order model can be constructed using snapshots that do not sample one entire turbine rotation (but only a fraction of it), which reduces the cost of generating the reduced order model. Additionally, we compare the reduced order model based on the high order Navier-Stokes solver to fast 2D simulations (using a Reynolds Averaged Navier-Stokes turbulent model) to illustrate the good performance of the proposed methodology.

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Blockage effects on the hydrodynamic performance of a marine cross-flow turbine

Cited by 62 publications

References 4 publications

The effect of blockage on tidal turbine rotor design and performance

The effect of blockage on tidal turbine rotor design and performance

Numerical investigation of laboratory tested cross-flow tidal turbines and Reynolds number scaling

A Reduced Order Model to Predict Transient Flows around Straight Bladed Vertical Axis Wind Turbines

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