Design of a Tidal Turbine Array for the Bohai Strait, China

2018 ◽  
Author(s):  
Lei Chen ◽  
Paul A. J. Bonar ◽  
Thomas A. A. Adcock
Keyword(s):  
Design Strategies ◽  
Stream Power ◽  
Tidal Turbines ◽  
Actuator Disc ◽  
Tidal Turbine ◽  
Tidal Stream ◽  
Flow Through ◽  
Turbine Arrays ◽  
Theoretical Results ◽  
Bohai Strait

In this paper, we consider array design strategies to maximise the power available to turbines placed in the Bohai Strait, which is considered to be one of China’s most promising candidate sites for tidal stream power. The discontinuous Galerkin version of the open-source hydrodynamic model ADCIRC is used to simulate flow through the strait and tidal turbines are introduced using a sub-grid scale actuator disc model. New design algorithms based on key theoretical results are used to build large arrays, which are then compared in terms of both the collective power output and the power produced per turbine. The results of the analysis are used to draw general conclusions about the optimal design of tidal turbine arrays.

scholarly journals Assessment of arrays of in-stream tidal turbines in the Bay of Fundy

2013 ◽  
Vol 371 (1985) ◽  
pp. 20120189 ◽  
Author(s):  
Richard Karsten ◽  
Amanda Swan ◽  
Joel Culina
Keyword(s):  
Power Generation ◽  
Electricity Generation ◽  
Bay Of Fundy ◽  
Blockage Ratio ◽  
Limit Value ◽  
Tidal Turbines ◽  
Actuator Disc ◽  
Flow Through ◽  
Turbine Arrays ◽  
The Impact

Theories of in-stream turbines are adapted to analyse the potential electricity generation and impact of turbine arrays deployed in Minas Passage, Bay of Fundy. Linear momentum actuator disc theory (LMADT) is combined with a theory that calculates the flux through the passage to determine both the turbine power and the impact of rows of turbine fences. For realistically small blockage ratios, the theory predicts that extracting 2000–2500 MW of turbine power will result in a reduction in the flow of less than 5 per cent. The theory also suggests that there is little reason to tune the turbines if the blockage ratio remains small. A turbine array model is derived that extends LMADT by using the velocity field from a numerical simulation of the flow through Minas Passage and modelling the turbine wakes. The model calculates the resulting speed of the flow through and around a turbine array, allowing for the sequential positioning of turbines in regions of strongest flow. The model estimates that over 2000 MW of power is possible with only a 2.5 per cent reduction in the flow. If turbines are restricted to depths less than 50 m, the potential power generation is reduced substantially, down to 300 MW. For large turbine arrays, the blockage ratios remain small and the turbines can produce maximum power with a drag coefficient equal to the Betz-limit value.

scholarly journals Experimental Assessment of Flow, Performance, and Loads for Tidal Turbines in a Closely-Spaced Array

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1977 ◽  
Author(s):  
Donald R. Noble ◽  
Samuel Draycott ◽  
Anup Nambiar ◽  
Brian G. Sellar ◽  
Jeffrey Steynor ◽  
...  
Keyword(s):  
Numerical Models ◽  
Ocean Energy ◽  
Complex Flow ◽  
Flow Measurements ◽  
Power Extraction ◽  
Tidal Turbines ◽  
Tidal Stream ◽  
Flow Through ◽  
And Performance ◽  
Structural Loading

Tidal stream turbines are subject to complex flow conditions, particularly when installed in staggered array configurations where the downstream turbines are affected by the wake and/or bypass flow of upstream turbines. This work presents, for the first time, methods for and results from the physical testing of three 1/15 scale instrumented turbines configured in a closely-spaced staggered array, and demonstrates experimentally that increased power extraction can be achieved through reduced array separation. A comprehensive set of flow measurements was taken during several weeks testing in the FloWave Ocean Energy Research Facility, with different configurations of turbines installed in the tank in a current of 0.8 m/s, to understand the effect that the front turbines have on flow through the array and on the inflow to the centrally placed rearmost turbine. Loads on the turbine structure, rotor, and blade roots were measured along with the rotational speed of the rotor to assess concurrently in real-time the effects of flow and array geometry on structural loading and performance. Operating in this closely-spaced array was found to improve the power delivered by the rear turbine by 5.7–10.4% with a corresponding increase in the thrust loading on the rotor of 4.8–7.3% around the peak power operating point. The experimental methods developed and results arising from this work will also be useful for further scale-testing elsewhere, validating numerical models, and for understanding the performance and loading of full-scale tidal stream turbines in arrays.

scholarly journals Accuracy of the actuator disc-RANS approach for predicting the performance and wake of tidal turbines

2013 ◽  
Vol 371 (1985) ◽  
pp. 20120293 ◽  
Author(s):  
W. M. J. Batten ◽  
M. E. Harrison ◽  
A. S. Bahaj
Keyword(s):  
Large Scale ◽  
Scale Effects ◽  
Tidal Energy ◽  
Rans Model ◽  
Tidal Turbines ◽  
Actuator Disc ◽  
Element Approach ◽  
Tidal Stream ◽  
Turbine Wake ◽  
Horizontal Axis Turbine

The actuator disc-RANS model has widely been used in wind and tidal energy to predict the wake of a horizontal axis turbine. The model is appropriate where large-scale effects of the turbine on a flow are of interest, for example, when considering environmental impacts, or arrays of devices. The accuracy of the model for modelling the wake of tidal stream turbines has not been demonstrated, and flow predictions presented in the literature for similar modelled scenarios vary significantly. This paper compares the results of the actuator disc-RANS model, where the turbine forces have been derived using a blade-element approach, to experimental data measured in the wake of a scaled turbine. It also compares the results with those of a simpler uniform actuator disc model. The comparisons show that the model is accurate and can predict up to 94 per cent of the variation in the experimental velocity data measured on the centreline of the wake, therefore demonstrating that the actuator disc-RANS model is an accurate approach for modelling a turbine wake, and a conservative approach to predict performance and loads. It can therefore be applied to similar scenarios with confidence.

On the Tidal Stream Resource of Two Headland Sites in the English Channel: Portland Bill and Isle of Wight

2014 ◽  
Author(s):  
Thomas A. A. Adcock ◽  
Scott Draper
Keyword(s):  
Field Measurements ◽  
Head Loss ◽  
English Channel ◽  
Mean Power ◽  
Isle Of Wight ◽  
Tidal Turbines ◽  
Actuator Disc ◽  
Tidal Stream ◽  
Tidal Stream Energy ◽  
The Mean

There are various candidate sites for tidal stream energy extraction in the English Channel. In this paper we examine the tidal stream resource at Portland Bill and the south coast of the Isle of Wight. A depth-averaged numerical model is developed and compared to field measurements. The presence of rows of tidal turbines is simulated using a line-discontinuity to represent the head loss across the turbines. The head loss is given by linear momentum actuator disc theory. At each site the length of the turbine rows, the local blockage ratio, and the location of the turbines are varied. For Portland Bill the presence of an array with multiple rows of turbines is also considered. We find that it is likely that (based purely on the hydrodynamics) power could viably be extracted at each site, with the mean power produced by each site being in the order of 10s MW.

scholarly journals A Note on the Effects of Local Blockage and Dynamic Tuning on Tidal Turbine Performance

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Lei Chen ◽  
Paul A.J. Bonar ◽  
Christopher R. Vogel ◽  
Thomas A.A. Adcock
Keyword(s):  
Oscillatory Flow ◽  
Tidal Channels ◽  
Scale Theory ◽  
Dynamic Tuning ◽  
Tidal Turbines ◽  
Turbine Performance ◽  
Actuator Disc ◽  
Tidal Turbine ◽  
Tuning Strategy ◽  
Blade Element

Abstract Numerical simulations are used to explore the potential for local blockage effects and dynamic tuning strategies to enhance the performance of turbines in tidal channels. Full- and partial-width arrays of turbines, modeled using the volume-flux-constrained actuator disc and blade element momentum theories, are embedded within a two-dimensional channel with a naturally low ratio of drag to inertial forces. For steady flow, the local blockage effect observed by varying the cross-stream spacing between the turbines is found to agree very well with the predictions of the two-scale actuator disc theory of Nishino and Willden (2012, “The Efficiency of an Array of Tidal Turbines Partially Blocking a Wide Channel,” J. Fluid Mech., 708, pp. 596–606). For oscillatory flow, however, results show that, consistent with the findings of Bonar et al. (2019, “On the Arrangement of Tidal Turbines in Rough and Oscillatory Channel Flow,” J. Fluid Mech., 865, pp. 790–810), the shorter and more highly blocked arrays produce considerably more power than predicted by two-scale theory. Results also show that, consistent with the findings of Vennell (2016, “An Optimal Tuning Strategy for Tidal Turbines,” Proc. R. Soc. A, 472(2195), p. 20160047), the “dynamic” tuning strategy, in which the tuning of the turbines is varied over the tidal cycle, can only produce significantly more power than a temporally fixed turbine tuning if the array has a large number of turbine rows or a large local blockage ratio. For all cases considered, trends are consistent between the two turbine representations but the effects of local blockage and dynamic tuning are found to be much less significant for the more realistic tidal rotor than for the idealized actuator disc.

Numerical Investigation of an Optimised Horizontal Axis Tidal Stream Turbine

2019 ◽  
Author(s):  
Hassan El Sheshtawy ◽  
Ould el Moctar ◽  
Thomas E. Schellin ◽  
Satish Natarajan
Keyword(s):  
Output Power ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Speed Ratio ◽  
Navier Stokes Equations ◽  
Tidal Turbines ◽  
Tidal Turbine ◽  
Sst Turbulence Model ◽  
Tidal Stream ◽  
Tidal Stream Turbine

Abstract A tidal stream turbine was designed using one of the optimised hydrofoils, whose lift-to-drag ratio at an angle of attack of 5.2 degrees was 4.5% higher than that of the reference hydrofoil. The incompressible Reynolds-averaged Navier Stokes equations in steady state were solved using k-ω (SST) turbulence model for the reference and optimised tidal stream turbines. The discretisation errors and the effect of different y+ values on the solution were analysed. Thrust and power coefficients of the modelled reference turbine were validated against experimental measurements. Output power and thrust of the reference and the optimised tidal turbines were compared. For a tip speed ratio of 3.0, the output power of the optimised tidal turbine was 8.27% higher than that of the reference turbine of the same thrust.

Centred and staggered arrangements of tidal turbines

2013 ◽  
Vol 739 ◽  
pp. 72-93 ◽  
Author(s):  
S. Draper ◽  
T. Nishino
Keyword(s):  
Average Power ◽  
Wind Farms ◽  
Fixed Number ◽  
Offshore Wind ◽  
Offshore Wind Farms ◽  
Pressure Equalization ◽  
Tidal Turbines ◽  
Actuator Disc ◽  
Staggered Arrangement ◽  
Tidal Turbine

AbstractIn this paper we extend linear momentum actuator disc theory to consider two rows of tidal turbines placed in a centred or staggered arrangement. The extensions assume a streamwise spacing between rows that is sufficient for pressure equalization, but is not too large for significant mixing of the upstream turbine wake before the second row. We first consider a given number of turbines in a tidal channel; in this case the average power for a staggered arrangement over two rows is found to be higher than that for a centred arrangement, but lower than can be obtained by placing all turbines side-by-side in one row (if all turbines have the same local resistance). Furthermore, staggered arrangements extract power more efficiently than centred arrangements, but less efficiently than a single row with the same number of turbines, and this has implications for ranking different arrangements of tidal turbines. We also use the extended actuator disc models (together with an argument of scale separation) to consider some example arrangements of tidal turbines in laterally unconfined flow. Specifically, it is shown that locally staggering a fixed number of turbines in an array to form a tidal farm generates less power than placing the same number of turbines side-by-side. However, if more than one row of turbines is adopted (perhaps to keep the farm spatially compact) then the optimum turbine spacing within a row increases significantly with addition of a second row. This trend suggests that multi-row tidal turbine farms would require wide turbine spacing within each row to maximize the power per turbine, similarly to existing offshore wind farms.

Optimization of the Rear Propeller Profile of a Counter-Rotating Type Tidal Stream Power Unit Based on CFD Simulation

2015 ◽  
Author(s):  
Bin Huang ◽  
Toshiaki Kanemoto ◽  
Ryunosuke Kawashima ◽  
Jin-Hyuk Kim
Keyword(s):  
Power Unit ◽  
Cfd Simulation ◽  
Mutual Effect ◽  
Stream Power ◽  
Power Efficient ◽  
Tidal Turbine ◽  
Tidal Stream ◽  
Tandem Propellers ◽  
Tidal Stream Power ◽  
Blade Element

In order to convert the kinetic energy of tidal stream, the authors have invented a novel counter-rotating type tidal-stream power unit, which is composed of the tandem propellers and the double rotational armature type peculiar generator without the traditional stator. The commercial code (GH-Tidal Bladed) and academic in-house code (SERG-Tidal) based on blade element momentum theory have been proven well applied to performance prediction for the traditional wind turbine and tidal turbine. However, for the counter-rotating type tidal turbine, it is very difficult to simulate the mutual effect between the tandem propellers using blade element momentum. This paper sets up a CFD model for the counter-rotating type tidal turbine and optimizes the chord and pitch distribution of the rear propeller. The predicted results are compared between the original turbine and optimized turbine, which show great improvement in power efficient after optimization.

scholarly journals Hybrid Neural Fuzzy Design-Based Rotational Speed Control of a Tidal Stream Generator Plant

2018 ◽  
Vol 10 (10) ◽  
pp. 3746 ◽  
Author(s):  
Khaoula Ghefiri ◽  
Izaskun Garrido ◽  
Soufiene Bouallègue ◽  
Joseph Haggège ◽  
Aitor Garrido
Keyword(s):  
Control Strategies ◽  
Reference Tracking ◽  
Power Extraction ◽  
Research Areas ◽  
Tidal Turbines ◽  
Control Scheme ◽  
Tidal Turbine ◽  
Tidal Stream ◽  
Rotational Speed Control ◽  
Neural Fuzzy

Artificial Intelligence techniques have shown outstanding results for solving many tasks in a wide variety of research areas. Its excellent capabilities for the purpose of robust pattern recognition which make them suitable for many complex renewable energy systems. In this context, the Simulation of Tidal Turbine in a Digital Environment seeks to make the tidal turbines competitive by driving up the extracted power associated with an adequate control. An increment in power extraction can only be archived by improved understanding of the behaviors of key components of the turbine power-train (blades, pitch-control, bearings, seals, gearboxes, generators and power-electronics). Whilst many of these components are used in wind turbines, the loading regime for a tidal turbine is quite different. This article presents a novel hybrid Neural Fuzzy design to control turbine power-trains with the objective of accurately deriving and improving the generated power. In addition, the proposed control scheme constitutes a basis for optimizing the turbine control approaches to maximize the output power production. Two study cases based on two realistic tidal sites are presented to test these control strategies. The simulation results prove the effectiveness of the investigated schemes, which present an improved power extraction capability and an effective reference tracking against disturbance.

scholarly journals The available power from tidal stream turbines in the Pentland Firth

2013 ◽  
Vol 469 (2157) ◽  
pp. 20130072 ◽  
Author(s):  
Thomas A. A. Adcock ◽  
Scott Draper ◽  
Guy T. Houlsby ◽  
Alistair G. L. Borthwick ◽  
Sena Serhadlıoğlu
Keyword(s):  
Numerical Model ◽  
Large Fraction ◽  
Field Measurements ◽  
Stream Power ◽  
Power Extraction ◽  
Actuator Disc ◽  
Tidal Stream ◽  
Set Up ◽  
Swept Area ◽  
Tidal Stream Power

This paper assesses an upper bound for the tidal stream power resource of the Pentland Firth. A depth-averaged numerical model of the tidal dynamics in the region is set-up and validated against field measurements. Actuator disc theory is used to model the effect of turbines on the flow, and to estimate the power available for generation after accounting for losses owing to mixing downstream of the turbines. It is found that three rows of turbines extending across the entire width of the Pentland Firth and blocking a large fraction of the channel can theoretically generate 1.9 GW, averaged over the spring–neap cycle. However, generation of significantly more power than this is unlikely to be feasible as the available power per additional swept area of turbine is too small to be viable. Our results differ from those obtained using simplified tidal channel models of the type used commonly in the literature. We also use our numerical model to investigate the available power from rows of turbines placed across various subchannels within the Pentland Firth, together with practical considerations such as the variation in power over the spring–neap tidal cycle and the changes to natural tidal flows which result from power extraction.

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