Tidal-stream power assessment—A novel modelling approach

Mateos, Lilia Flores; Hartnett, Michael

doi:10.1016/j.egyr.2019.08.027

Cited by 2 publications

(10 citation statements)

References 6 publications

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“…This suggests that the faster array-bypass flow computed with ADI model is influencing the velocities at the partial-fence edges. The smaller velocity reduction presented in ADI's velocity solutions is consistent with [45]. They indicated that a gradual varying flow scheme under-estimate the velocity decrease produced by momentum extraction; meanwhile, a rapidly varying flow scheme approximates more accurately this reduction due to its capacity to solve the velocity spatial gradients generated during energy extraction.…”

Section: Upstream Velocitiessupporting

confidence: 64%

“…This dependency indicates that P W solutions are also explained by head drop values. For bounded flows, P W values obtained with ADI are reliable solutions [45]. In the case of unbounded flows scenario, P W magnitudes obtained from the models are slightly smaller than the fence.…”

Section: Power Metricsmentioning

confidence: 71%

“…The larger magnitude of C T reported by ADI is associated with the smaller affectation of the momentum extraction on the bypass velocity reduction (represented by β 4 ). ADI underestimation of velocity reduction due to power extraction was reported by [45]. In the case of C P , the turbine velocity coefficient reduces the difference between the magnitudes obtained from the models.…”

Section: Thrust and Power Coefficients Time Seriesmentioning

confidence: 91%

“…Coefficients of the polynomial are a function of blockage ratio, thrust coefficient, and Froude number. C T and F r were obtained from TVD simulations, as this scheme approximates the velocity reduction more accurately for a fence scenario [45]. Meanwhile, numerical solutions correspond to head drops obtained from depth differences across the array at upstream and downstream locations.…”

Section: Head Drop and Turbine Efficiencymentioning

confidence: 99%

“…P T is a function of water drop and the increase of blockage ratio produces a head drop augmentation which is responsible of larger values of total power extracted. For bounded flows (F), [45] indicated that P T is accurately approximated by an ADI model because a GVF solver approximates better the head drops across a fence. For unbounded flows scenario (PF), P T magnitudes obtained from ADI and TVD are smaller than the fence.…”

Section: Power Metricsmentioning

confidence: 99%

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Incorporation of a Non-Constant Thrust Force Coefficient to Assess Tidal-Stream Energy

Mateos

Hartnett

2019

Energies

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A novel method for modelling tidal-stream energy capture at the regional scale is used to evaluate the performance of two marine turbine arrays configured as a fence and a partial fence. These configurations were used to study bounded and unbounded flow scenarios, respectively. The method implemented uses turbine operating conditions (TOC) and the parametrisation of changes produced by power extraction within the turbine near-field to compute a non-constant thrust coefficient, and it is referred to as a momentum sink TOC. Additionally, the effects of using a shock-capture capability to evaluate the resource are studied by comparing the performance of a gradually varying flow (GVF) and a rapidly varying flow (RVF) solver. Tidal-stream energy assessment of bounded flow scenarios through a full fence configuration is better performed using a GVF solver, because the head drop is more accurately simulated; however, the solver underestimates velocity reductions due to power extraction. On the other hand, assessment of unbounded flow scenarios through a partial fence was better performed by the RVF solver. This scheme approximated the head drop and velocity reduction more accurately, thus suggesting that resource assessment with realistic turbine configurations requires the correct solution of the discontinuities produced in the tidal-stream by power extraction.

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Section: Upstream Velocitiessupporting

confidence: 64%

Section: Power Metricsmentioning

confidence: 71%

Section: Thrust and Power Coefficients Time Seriesmentioning

confidence: 91%

Section: Head Drop and Turbine Efficiencymentioning

confidence: 99%

Section: Power Metricsmentioning

confidence: 99%

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Incorporation of a Non-Constant Thrust Force Coefficient to Assess Tidal-Stream Energy

Mateos

Hartnett

2019

Energies

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Hydrodynamic Effects of Tidal-Stream Power Extraction for Varying Turbine Operating Conditions

Mateos

Hartnett

2020

Energies

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Realistic evaluation of tidal-stream power extraction effects on local hydrodynamics requires the inclusion of the turbine’s operating conditions (TOC). An alternative approach for simulating the turbine’s array energy capture at a regional scale, momentum sink-TOC, is used to assess the impact of power extraction. The method computes a non-constant thrust force calculated based on the turbine’s operating conditions, and it uses the wake induction factor and blockage ratio to characterise the performance of a turbine. Additionally, the momentum sink-TOC relates the changes produced by power extraction, on the velocity and sea surface within the turbine’s near-field extension, to the turbine’s thrust force. The method was implemented in two hydrodynamic models that solved gradually varying flows (GVF) and rapidly varying flows (RVF). The local hydrodynamic effects produced by tidal-stream power extraction for varying the turbine’s operating conditions was investigated in (i) the thrust and power coefficient calculation, (ii) flow rate reduction, and (iii) tidal currents’ velocity and elevation profiles. Finally, for a turbine array that operates at optimal conditions, the potential energy resource was assessed. The maximisation of power extraction for electrical generation requires the use of an optimum turbine wake induction factor and an adequate blockage ratio, so that the power loss due to turbine wake mixing is reduced. On the other hand, the situations where limiting values of these parameters are used should be avoided as they lead to negligible power available. In terms of hydrodynamical models, an RVF solver provided a more accurate evaluation of the turbine’s operating conditions effect on local hydrodynamics. Particularly satisfactory results were obtained for a partial-fence. In the case of a fence configuration, the GVF solver was found to be a computationally economical tool to pre-assess the resource; however, caution should be taken as the solver did not accurately approximate the velocity decrease produced by energy extraction.

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Tidal-stream power assessment—A novel modelling approach

Cited by 2 publications

References 6 publications

Incorporation of a Non-Constant Thrust Force Coefficient to Assess Tidal-Stream Energy

Incorporation of a Non-Constant Thrust Force Coefficient to Assess Tidal-Stream Energy

Hydrodynamic Effects of Tidal-Stream Power Extraction for Varying Turbine Operating Conditions

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