scholarly journals A Design Procedure for Anchors of Floating Ocean Current Turbines on Weak Rock

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7347
Author(s):  
Francisco Bañuelos-García ◽  
Michael Ring ◽  
Edgar Mendoza ◽  
Rodolfo Silva

In recent years, ocean current turbines have proven to be a reliable device for renewable energy generation. A crucial element of these turbines are the foundations, since they limit the displacement of the turbine, which is key in achieving efficiency in energy conversion, and can account for up to 26% of the total cost of the project. Most design procedures for foundations focus on sandy and clayey soils, but rock soils often predominate in tropical locations where marine currents are suitable for the installation of this type of turbine. This paper presents a design procedure for steel pile anchors (PAs) and concrete dead weight anchors (DWAs) on weak rock soils, using the assumptions of current technical documents and design codes commonly used in the industry for marine structures. Using specific designs for PA and DWA anchors, the procedure was theoretically assessed for a site off Cozumel Island, Mexico. The results show that the dimensions needed for DWAs are substantially larger than those for PAs. Therefore, whenever drilling is economically and operatively possible, piles would be preferable for the foundations of current turbine systems.

2021 ◽  
Author(s):  
Hassan Mahfuz ◽  
Nicholas Asseff ◽  
Mohammad Wasim Akram ◽  
Fang Zhou ◽  
Takuya Suzuki ◽  
...  

The renewable energy generation initiatives contain a low-cost viable option for the electric consumer worldwide. The efficient methodologies of wind, solar, ocean current, and geothermal power generation are attractive alternatives to fossil fuels. Based on the current condition of the infrastructure, most of the proposed wind energy projects require transmission line upgrades. In some regional impact studies, the existing transmission system may have sufficient capability to handle the power from the planned renewable generating sources. Nevertheless, integrating large amounts of wind power (even small amounts in some areas) will require some form of infrastructure upgrades.


2017 ◽  
Vol 23 (4) ◽  
pp. 275-289
Author(s):  
Benjamin D. Haugen

Abstract Infiltration of surface water increases pore water pressures in slopes and reduces their stability. Common landslide features such as tension cracks and sag ponds can act as preferential pathways for surface drainage and may increase infiltration and exacerbate pore pressure–induced instability. Surface water drainage control is likewise recommended by numerous authors as an effective and inexpensive landslide mitigation method and has been shown to reduce the risk of landslides. While robust design procedures for other geotechnical applications exist (e.g., slope reduction, subsurface drains), similar procedures for landslide surface water drainage control have remained largely ad hoc and vary among practitioners. The objective of this article is to summarize technical literature related to surface water drainage control and provide a coherent design procedure for landslides.


Author(s):  
H. Suzuki ◽  
H. R. Riggs ◽  
M. Fujikubo ◽  
T. A. Shugar ◽  
H. Seto ◽  
...  

Very Large Floating Structure (VLFS) is a unique concept of ocean structures primary because of their unprecedented length, displacement cost and associated hydroelastic response. International Ship and Offshore Structures Congress (ISSC) had paid attention to the emerging novel technology and launched Special Task Committee to investigate the state of the art in the technology. This paper summarizes the activities of the committee. A brief overview of VLFS is given first for readers new to the subject. History, application and uniqueness with regard to engineering implication are presented. The Mobile Offshore Base (MOB) and Mega-Float, which are typical VLFS projects that have been investigated in detail and are aimed to be realized in the near future, are introduced. Uniqueness of VLFS, such as differences in behavior of VLFS from conventional ships and offshore structures, are described. The engineering challenges associated with behavior, design procedure, environment, and the structural analysis of VLFS are introduced. A comparative study of hydroelastic analysis tools that were independently developed for MOB and Mega-Float is made in terms of accuracy of global behavior. The effect of structural modeling on the accuracy of stress analysis is also discussed. VLFS entails innovative design methods and procedure. Development of design criteria and design procedures are described and application of reliability-based approaches are documented and discussed.


Author(s):  
T. Karthikeyan ◽  
E. J. Avital ◽  
N. Venkatesan ◽  
A. Samad

Ocean stores a huge amount of energy and ocean current energy can be a viable source in future. In this article, an axial marine current turbine has been optimized to enhance its power coefficient through numerical modeling. The blade pitch-angle and number of blades are the design parameters chosen for the analysis to find the optimal design. A commercial code for CFD simulations with in-house optimization code was used for the analysis. It was found that, changing the blade pitch-angle and reducing the number of blades can improve the turbine’s coefficient of power. This is due to increase in lift and reduction of losses caused by turbulence near the downstream of the turbine. The article presents flow-simulation difficulties and characteristic curves to identify the differences between the actual and optimized turbine. The detailed flow physics is discussed and pictured in the post processed plots.


Author(s):  
Linda M. Pierce ◽  
Joe P. Mahoney

During the late 1980s, the Washington State Department of Transportation (WSDOT), the University of Washington, and the Washington State Transportation Center developed a mechanistic-empirical flexible overlay design procedure. Following development, WSDOT implemented this overlay design procedure and has been evaluating flexible overlay projects for approximately the past 8 years. WSDOT rehabilitates about 100 projects each year; approximately 20 to 30 percent of the total projects are designed using the WSDOT overlay design procedure and the AASHTO overlay design procedure (using DARWin). These two procedures are discussed in general, and two case studies illustrate each of the overlay design procedures. Also included is the backcalculation of layer moduli from falling weight deflectometer data.


2020 ◽  
Vol 12 (8) ◽  
pp. 3333
Author(s):  
Nauman Riyaz Maldar ◽  
Cheng Yee Ng ◽  
Lee Woen Ean ◽  
Elif Oguz ◽  
Ahmad Fitriadhy ◽  
...  

Several different designs and prototypes of ocean current turbines have been tested over recent years. For every design test, emphasis is given to achieving an optimum power output from the flow. In this study, the performance of a Horizontal Axis Ocean Current Turbine (HAOCT) has been investigated using three-dimensional Computational Fluid Dynamics (CFD) simulations for three cases, namely, (1) a turbine without a deflector, (2) a turbine with a deflector, and (3) a turbine with a deflector operating at a higher fluid depth. The turbine design was modeled in DesignModeler software and simulations were carried out in commercial CFD software Flow-3D. The Torque Coefficient (Cm) and Power Coefficient (Cp) for the turbine have been investigated for a certain range of Tip-Speed Ratios (TSRs) in a flow velocity of 0.7 m/s. Furthermore, comparisons have been made to demonstrate the effect of the deflector on the performance of the turbine and the influence of a higher fluid pressure on the same. The results from the simulations indicate that the higher value of Cp was achieved for Case 2 as compared to the other two cases. The findings from the study indicate that the use of the deflector enhances the performance of the turbine. Furthermore, a higher fluid pressure acting on the turbine has a significant effect on its performance.


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