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Pablo Tassi - One of the best experts on this subject based on the ideXlab platform.

  • Hydrodynamics of a hyper-Tidal estuary influenced by the world's second largest Tidal Power Station (Rance estuary, France)
    Estuarine Coastal and Shelf Science, 2021
    Co-Authors: Rajae Rtimi, Aldo Sottolichio, Pablo Tassi
    Abstract:

    Abstract The Rance estuary is a relatively small low-discharge steep-sided ria, located along the Brittany coast in northern France, with a maximum spring Tidal range of 13.5 m. Taking advantage of this hyper-Tidal regime, the first and currently the second largest operational Tidal Power Station in the world was built at the estuary's mouth and has been in operation since the 1960s. Despite the well-known effect of damping of estuarine water levels, little attention has been given to quantifying the influence of the plant on the propagation and asymmetry of the Tidal wave inside the estuary. In this study, hydrodynamics and Tidal wave patterns were analyzed in this anthropogenically influenced estuarine system. A two-dimensional depth-averaged numerical model of the Rance estuary was developed. Two scenarios without the Tidal Power plant involving the dam's pre- and post-construction bathymetry (1957 and 2018 respectively) and present-day conditions scenarios were designed, to highlight the impact of bed evolution and the Tidal Power Station on hydrodynamics and Tidal asymmetry. Numerical results showed that, without the structure, bathymetric evolution did not substantially influence estuarine hydrodynamics. Nevertheless, on the estuary-side of the dam, the presence of the Tidal Power plant induced (i) a decrease in both Tidal range and Tidal prism, (ii) an increase of low water levels, and (iii) a decrease in both flood and ebb currents. Contrastingly, the region close to the structure reacted differently to plant operating modes, with an increase in flood currents (ebb currents) upstream of the sluice gates (downstream of the turbines). For both the natural condition and the artificially-induced hydrodynamic forcing due to the presence of the plant, numerical results showed that the Rance estuary mainly exhibits flood-dominant behavior, with a longer duration of falling than rising water and stronger peak flood currents than ebb currents. Spanning a period of approximately 60 years, this study presents a quantitative analysis of the influence of the Tidal Power Station on the hydrodynamics in the Rance estuary, and its possible consequences for sediment dynamics. This approach is novel for this particular enclosed water body, characterized by the presence of a dam at its mouth and a lock at its uppermost limit.

  • Tidal Patterns and Sediment Dynamics in a HyperTidal Estuary Influenced by a Tidal Power Station
    Journal of Coastal Research, 2020
    Co-Authors: Rajae Rtimi, Aldo Sottolichio, Pablo Tassi
    Abstract:

    Rtimi, R.; Sottolichio, A. and Tassi, P., 2020. Tidal patterns and sediment dynamics in a hyperTidal estuary influenced by a Tidal Power Station. In: Malvarez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 1520–1524. Coconut Creek (Florida), ISSN 0749-0208.The Rance estuary is a relatively small low-inflow steep-sided ria, located in the Brittany coast of northern France, with a maximum spring Tidal range of 13.5 m at the mouth. Taking advantage of this hyperTidal regime, the first and largest operational Tidal Power Station in the world was built at the estuary mouth and is in operation since the 1960s. Despite a well-known effect of the plant on the damping of estuarine water levels, little attention has been given to the propagation of the Tidal wave along the estuary. Moreover, net siltation has been reported by several observations, but there is no specific knowledge on the role of the plant on sedimentation. In this study, Tidal wave patterns and sediment dynamics are analyzed in this particular man-engineered system. A numerical model, based on a two-dimensional depth-averaged approach is implemented to predict the tide propagation and Tidal currents along the estuary. Numerical results are analyzed and discussed to highlight the role of the plant on the transformation of the Tidal wave in the estuary and its possible consequences on sediment dynamics and morphological evolution.

  • The Rance Tidal Power Station: a preliminary study of its impact on Tidal patterns and sediments dynamics in the Rance estuary (France) from 1957 to 2018
    2020
    Co-Authors: Rajae Rtimi, Aldo Sottolichio, Pablo Tassi
    Abstract:

    <p>The Rance Tidal Power Station (located on the Brittany coast of Northern France), was opened in 1966 as the world’s first and largest Tidal Power Station, with peak output capacity of 240 Megawatts. It is currently the second world’s largest Tidal Power installation after the Sihwa Lake Tidal Power Station (South Korea). The Power plant is located at the mouth of a small steep-sided ria, with a maximum perigean spring Tidal range of 13.5 m and an average fluvial discharge of 7 m<sup>3</sup>/s. The dam is 750 m long and the Tidal basin measures 22.5 km<sup>2</sup>. Despite a well-known effect of the plant on the damping of estuarine water levels, little attention has been given to the consequences of the dam in the estuarine environment in terms of hydrodynamics, for instance, the propagation of the Tidal wave and Tidal currents along the estuary are still little understood. Moreover, net siltation has been reported by several observations, but there is no specific knowledge on the role of the plant on sedimentation. In this study, we analyze the impact of the Tidal Power Station on Tidal wave patterns and sediment dynamics in this particular man-engineered system. To this goal, a numerical model based on a two-dimensional depth-averaged approach is implemented to predict the tide propagation and Tidal currents along the estuary accounting for the presence of the Tidal Power Station. Three modelling scenarios were performed: the first considering the bathymetry of 1957 (before the plant’s construction), a second scenario considering the bathymetry of 2018 without the presence of the Power Station and a third scenario considering the bathymetry of 2018 with the Power Station. Preliminary results showed that, with and without the Tidal Power Station, the upper estuary exhibits a flood dominant behavior, with longer duration of falling water than rising water, and conversely the lower estuary is ebb dominant with shorter duration of falling water than rising water. This analysis also revealed that the Tidal Power Station might switch the flood dominance in the central estuary to ebb dominance. These findings imply a net seaward transport of both coarse and fine sediments in the lower estuary. Therefore, the Tidal Power Station might have a considerable role in modulating the estuarine turbidity maximum and channels’ morphology. Finally, these results are compared with preliminary numerical simulations of suspended sediment transport to further quantify the impact of the Tidal Power plant on the dynamics of the estuarine turbidity maximum.</p>

J.p. Frau - One of the best experts on this subject based on the ideXlab platform.

  • Tidal energy: promising projects: La Rance, a successful industrial-scale experiment
    IEEE Transactions on Energy Conversion, 1993
    Co-Authors: J.p. Frau
    Abstract:

    In some few special areas of the world, the range of the variation of the sea level due to the tide can be impressive. For centuries man has been harnessing this energy with the operation of Tidal mills. At present, the design of Tidal Power does not present new scientific issues. Nevertheless, additional research and development should be carried out in three fields: interface of the Tidal Power Station output with National Grids and above all a sound assessment of its economic interest; design and implementation of work according to the site; and environmental effects. On November 26, 1966, the La Rance Tidal Power Station was inaugurated after 25 years of design in various fields, and 25 years afterwards it is still the only industrial prototype of a large size Tidal Power Station. Currently several important schemes are also under study throughout the world. >

Rajae Rtimi - One of the best experts on this subject based on the ideXlab platform.

  • Hydrodynamics of a hyper-Tidal estuary influenced by the world's second largest Tidal Power Station (Rance estuary, France)
    Estuarine Coastal and Shelf Science, 2021
    Co-Authors: Rajae Rtimi, Aldo Sottolichio, Pablo Tassi
    Abstract:

    Abstract The Rance estuary is a relatively small low-discharge steep-sided ria, located along the Brittany coast in northern France, with a maximum spring Tidal range of 13.5 m. Taking advantage of this hyper-Tidal regime, the first and currently the second largest operational Tidal Power Station in the world was built at the estuary's mouth and has been in operation since the 1960s. Despite the well-known effect of damping of estuarine water levels, little attention has been given to quantifying the influence of the plant on the propagation and asymmetry of the Tidal wave inside the estuary. In this study, hydrodynamics and Tidal wave patterns were analyzed in this anthropogenically influenced estuarine system. A two-dimensional depth-averaged numerical model of the Rance estuary was developed. Two scenarios without the Tidal Power plant involving the dam's pre- and post-construction bathymetry (1957 and 2018 respectively) and present-day conditions scenarios were designed, to highlight the impact of bed evolution and the Tidal Power Station on hydrodynamics and Tidal asymmetry. Numerical results showed that, without the structure, bathymetric evolution did not substantially influence estuarine hydrodynamics. Nevertheless, on the estuary-side of the dam, the presence of the Tidal Power plant induced (i) a decrease in both Tidal range and Tidal prism, (ii) an increase of low water levels, and (iii) a decrease in both flood and ebb currents. Contrastingly, the region close to the structure reacted differently to plant operating modes, with an increase in flood currents (ebb currents) upstream of the sluice gates (downstream of the turbines). For both the natural condition and the artificially-induced hydrodynamic forcing due to the presence of the plant, numerical results showed that the Rance estuary mainly exhibits flood-dominant behavior, with a longer duration of falling than rising water and stronger peak flood currents than ebb currents. Spanning a period of approximately 60 years, this study presents a quantitative analysis of the influence of the Tidal Power Station on the hydrodynamics in the Rance estuary, and its possible consequences for sediment dynamics. This approach is novel for this particular enclosed water body, characterized by the presence of a dam at its mouth and a lock at its uppermost limit.

  • Tidal Patterns and Sediment Dynamics in a HyperTidal Estuary Influenced by a Tidal Power Station
    Journal of Coastal Research, 2020
    Co-Authors: Rajae Rtimi, Aldo Sottolichio, Pablo Tassi
    Abstract:

    Rtimi, R.; Sottolichio, A. and Tassi, P., 2020. Tidal patterns and sediment dynamics in a hyperTidal estuary influenced by a Tidal Power Station. In: Malvarez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 1520–1524. Coconut Creek (Florida), ISSN 0749-0208.The Rance estuary is a relatively small low-inflow steep-sided ria, located in the Brittany coast of northern France, with a maximum spring Tidal range of 13.5 m at the mouth. Taking advantage of this hyperTidal regime, the first and largest operational Tidal Power Station in the world was built at the estuary mouth and is in operation since the 1960s. Despite a well-known effect of the plant on the damping of estuarine water levels, little attention has been given to the propagation of the Tidal wave along the estuary. Moreover, net siltation has been reported by several observations, but there is no specific knowledge on the role of the plant on sedimentation. In this study, Tidal wave patterns and sediment dynamics are analyzed in this particular man-engineered system. A numerical model, based on a two-dimensional depth-averaged approach is implemented to predict the tide propagation and Tidal currents along the estuary. Numerical results are analyzed and discussed to highlight the role of the plant on the transformation of the Tidal wave in the estuary and its possible consequences on sediment dynamics and morphological evolution.

  • The Rance Tidal Power Station: a preliminary study of its impact on Tidal patterns and sediments dynamics in the Rance estuary (France) from 1957 to 2018
    2020
    Co-Authors: Rajae Rtimi, Aldo Sottolichio, Pablo Tassi
    Abstract:

    <p>The Rance Tidal Power Station (located on the Brittany coast of Northern France), was opened in 1966 as the world’s first and largest Tidal Power Station, with peak output capacity of 240 Megawatts. It is currently the second world’s largest Tidal Power installation after the Sihwa Lake Tidal Power Station (South Korea). The Power plant is located at the mouth of a small steep-sided ria, with a maximum perigean spring Tidal range of 13.5 m and an average fluvial discharge of 7 m<sup>3</sup>/s. The dam is 750 m long and the Tidal basin measures 22.5 km<sup>2</sup>. Despite a well-known effect of the plant on the damping of estuarine water levels, little attention has been given to the consequences of the dam in the estuarine environment in terms of hydrodynamics, for instance, the propagation of the Tidal wave and Tidal currents along the estuary are still little understood. Moreover, net siltation has been reported by several observations, but there is no specific knowledge on the role of the plant on sedimentation. In this study, we analyze the impact of the Tidal Power Station on Tidal wave patterns and sediment dynamics in this particular man-engineered system. To this goal, a numerical model based on a two-dimensional depth-averaged approach is implemented to predict the tide propagation and Tidal currents along the estuary accounting for the presence of the Tidal Power Station. Three modelling scenarios were performed: the first considering the bathymetry of 1957 (before the plant’s construction), a second scenario considering the bathymetry of 2018 without the presence of the Power Station and a third scenario considering the bathymetry of 2018 with the Power Station. Preliminary results showed that, with and without the Tidal Power Station, the upper estuary exhibits a flood dominant behavior, with longer duration of falling water than rising water, and conversely the lower estuary is ebb dominant with shorter duration of falling water than rising water. This analysis also revealed that the Tidal Power Station might switch the flood dominance in the central estuary to ebb dominance. These findings imply a net seaward transport of both coarse and fine sediments in the lower estuary. Therefore, the Tidal Power Station might have a considerable role in modulating the estuarine turbidity maximum and channels’ morphology. Finally, these results are compared with preliminary numerical simulations of suspended sediment transport to further quantify the impact of the Tidal Power plant on the dynamics of the estuarine turbidity maximum.</p>

Chunxia Yang - One of the best experts on this subject based on the ideXlab platform.

  • Inlet Passage’s Development and Optimization of New Tidal Unit-Shaft
    2016
    Co-Authors: Tubular Turbine, Chunxia Yang, Yuan Zheng
    Abstract:

    opening Abstract. A new type of Tidal unit-vertical shaft tubular turbine is designed with high efficiency, large flow rate and low water head,which has large Power under the 2~3 meters water head. According to the data of the being installed Tidal units and principles of tubular turbine’s design, the high efficiency vertical shaft tubular turbine was designed under large discharge and low head, which was suitable for the Tidal Power Station. The design also considered the requirements of turbine’s size and the details of flow through the whole flow passage were attained. The turbine’s property was predicted by the 3-d numerical simulation software on the whole flow passage. Moreover, the influences of vertical shaft’s sizes were analyzed. And the terminal of vertical shaft with or without transverse brace and longitudinal brace were analyzed to get the influence. Considering the hydraulic performance of various methods, the best guide vane opening was chosen. The results show that, the turbine unit has the best performance on efficiency, hydraulic loss, etc. with the guide vane opening 62°, meeting the Power Station’s design requirements. The results show that the optimal designed flow passage’s efficiency reaches up to 88.4%, the flow rate becomes much larger and the Power reaches 174.63kW. Without partial vortex, the flow pattern is smooth through the whole passage also with lower hydraulic loss

  • Inlet Passage’s Development and Optimization of New Tidal Unit-Shaft Tubular Turbine
    Applied Mechanics and Materials, 2014
    Co-Authors: Chunxia Yang, Yuan Zheng, Xiao Qing Tian, Yu Quan Zhang
    Abstract:

    A new type of Tidal unit-vertical shaft tubular turbine is designed with high efficiency, large flow rate and low water head ,which has large Power under the 2~3 meters water head. According to the data of the being installed Tidal units and principles of tubular turbine’s design, the high efficiency vertical shaft tubular turbine was designed under large discharge and low head, which was suitable for the Tidal Power Station. The design also considered the requirements of turbine’s size and the details of flow through the whole flow passage were attained. The turbine’s property was predicted by the 3-d numerical simulation software on the whole flow passage. Moreover, the influences of vertical shaft’s sizes were analyzed. And the terminal of vertical shaft with or without transverse brace and longitudinal brace were analyzed to get the influence. Considering the hydraulic performance of various methods, the best guide vane opening was chosen. The results show that, the turbine unit has the best performance on efficiency, hydraulic loss, etc. with the guide vane opening 62°, meeting the Power Station’s design requirements. The results show that the optimal designed flow passage’s efficiency reaches up to 88.4%, the flow rate becomes much larger and the Power reaches 174.63kW. Without partial vortex, the flow pattern is smooth through the whole passage also with lower hydraulic loss.

  • Optimization Study of Shaft Tubular Turbine in a Bidirectional Tidal Power Station
    Advances in Mechanical Engineering, 2013
    Co-Authors: Ge Xinfeng, Yuan Feng, Ye Zhou, Yuan Zheng, Chunxia Yang
    Abstract:

    The shaft tubular turbine is a form of Tidal Power Station which can provide bidirectional Power. Efficiency is an important turbine performance indicator. To study the influence of runner design parameters on efficiency, a complete 3D flow-channel model of a shaft tubular turbine was developed, which contains the turbine runner, guide vanes, and flow passage and was integrated with hybrid grids calculated by steady-state calculation methods. Three aspects of the core component (turbine runner) were optimized by numerical simulation. All the results were then verified by experiments. It was shown that curved-edge blades are much better than straight-edge blades; the optimal blade twist angle is 7°, and the optimal distance between the runner and the blades is 0.75–1.25 times the diameter of the runner. Moreover, the numerical simulation results matched the experimental data very well, which also verified the correctness of the optimal results.

Yuan Zheng - One of the best experts on this subject based on the ideXlab platform.

  • Inlet Passage’s Development and Optimization of New Tidal Unit-Shaft
    2016
    Co-Authors: Tubular Turbine, Chunxia Yang, Yuan Zheng
    Abstract:

    opening Abstract. A new type of Tidal unit-vertical shaft tubular turbine is designed with high efficiency, large flow rate and low water head,which has large Power under the 2~3 meters water head. According to the data of the being installed Tidal units and principles of tubular turbine’s design, the high efficiency vertical shaft tubular turbine was designed under large discharge and low head, which was suitable for the Tidal Power Station. The design also considered the requirements of turbine’s size and the details of flow through the whole flow passage were attained. The turbine’s property was predicted by the 3-d numerical simulation software on the whole flow passage. Moreover, the influences of vertical shaft’s sizes were analyzed. And the terminal of vertical shaft with or without transverse brace and longitudinal brace were analyzed to get the influence. Considering the hydraulic performance of various methods, the best guide vane opening was chosen. The results show that, the turbine unit has the best performance on efficiency, hydraulic loss, etc. with the guide vane opening 62°, meeting the Power Station’s design requirements. The results show that the optimal designed flow passage’s efficiency reaches up to 88.4%, the flow rate becomes much larger and the Power reaches 174.63kW. Without partial vortex, the flow pattern is smooth through the whole passage also with lower hydraulic loss

  • Inlet Passage’s Development and Optimization of New Tidal Unit-Shaft Tubular Turbine
    Applied Mechanics and Materials, 2014
    Co-Authors: Chunxia Yang, Yuan Zheng, Xiao Qing Tian, Yu Quan Zhang
    Abstract:

    A new type of Tidal unit-vertical shaft tubular turbine is designed with high efficiency, large flow rate and low water head ,which has large Power under the 2~3 meters water head. According to the data of the being installed Tidal units and principles of tubular turbine’s design, the high efficiency vertical shaft tubular turbine was designed under large discharge and low head, which was suitable for the Tidal Power Station. The design also considered the requirements of turbine’s size and the details of flow through the whole flow passage were attained. The turbine’s property was predicted by the 3-d numerical simulation software on the whole flow passage. Moreover, the influences of vertical shaft’s sizes were analyzed. And the terminal of vertical shaft with or without transverse brace and longitudinal brace were analyzed to get the influence. Considering the hydraulic performance of various methods, the best guide vane opening was chosen. The results show that, the turbine unit has the best performance on efficiency, hydraulic loss, etc. with the guide vane opening 62°, meeting the Power Station’s design requirements. The results show that the optimal designed flow passage’s efficiency reaches up to 88.4%, the flow rate becomes much larger and the Power reaches 174.63kW. Without partial vortex, the flow pattern is smooth through the whole passage also with lower hydraulic loss.

  • Optimization Study of Shaft Tubular Turbine in a Bidirectional Tidal Power Station
    Advances in Mechanical Engineering, 2013
    Co-Authors: Ge Xinfeng, Yuan Feng, Ye Zhou, Yuan Zheng, Chunxia Yang
    Abstract:

    The shaft tubular turbine is a form of Tidal Power Station which can provide bidirectional Power. Efficiency is an important turbine performance indicator. To study the influence of runner design parameters on efficiency, a complete 3D flow-channel model of a shaft tubular turbine was developed, which contains the turbine runner, guide vanes, and flow passage and was integrated with hybrid grids calculated by steady-state calculation methods. Three aspects of the core component (turbine runner) were optimized by numerical simulation. All the results were then verified by experiments. It was shown that curved-edge blades are much better than straight-edge blades; the optimal blade twist angle is 7°, and the optimal distance between the runner and the blades is 0.75–1.25 times the diameter of the runner. Moreover, the numerical simulation results matched the experimental data very well, which also verified the correctness of the optimal results.

  • Research on Energy Characteristics of Bidirectional Tubular Turbine
    Volume 2: Fora Parts A and B, 2007
    Co-Authors: Yuan Zheng, Zai-ming Geng, Bao-luo Wang, Bo-qin Fan
    Abstract:

    Combining a Tidal Power Station in China, numerical simulation on energy characteristics of bidirectional tubular turbine is performed using standard k–e model, which was used to simulate turbulent flow with high Reynolds number and is applicable to fully developed turbulent flow. This simple and economical model ensures sufficient precision in the large project simulation. Structural mesh is applied in the mesh division, for it was convenient to dispose of boundary conditions with high precision. By using high performance implicit algorithm and multi-grid algorithm, the efficiency of simulation using structural mesh is higher than other models. The simulation control zones are comprised of inlet (including bulb unit), guide vane, runner and draft tube. Boundary conditions were comprised of entrance of intake tube and export of draft tube. The inlet of turbine is a regular circular tube, where the velocity of flow is perpendicular to inlet. The water is directly discharged to downstream thus free outflow is adopted in the simulation. The numerical simulation is divided into positive and negative conditions. On the positive condition, the simulation results show that to the same guide vane opening, the discharge becomes larger and the rotational speed becomes slower with the angle of runner blade increasing. To the same angle of runner blade, the discharge becomes larger and the rotational speed becomes higher when the guide vane opening becomes larger. The highest efficiency of positive direction in the simulation is 75.8% and the optimist angle of runner blade is 15°. The simulation results agree with the results of model test generally, and the efficiency in simulation is lower than that in model test with value of 2%∼9%. And the results of simulation are close to the tested ones when the guide vane opening is near 60°. Under this guide vane opening, when the runner blade is 15°, the efficiency in the simulation was 72% while in the test the value is 74%, thus the difference between numerical simulation and model test is 2%. So, good results are obtained through numerical simulation. Under the negative condition, the discharge becomes larger with the angle of runner blade increasing in the same unit speed. The discharge becomes larger with the unit speed increasing with the same angle of blade. The highest calculated efficiency is 66.6% in this condition, and the optimist angel of the runner blade is 10°. The efficiency in the numerical simulation is lower than the value in model test, which also occurs in the positive condition. However, the difference between simulation and test is less than the one in the positive condition. The average difference is 2.5%, and it can be concluded that the difference value becomes smaller with the unit speed increasing. The values in the numerical simulation are near to the test ones. From results obtained above, numerical simulation can make comparatively accurate estimation for the energy characteristics of tubular turbine, and direct to the hydraulic design of turbine units.Copyright © 2007 by ASME