Application of a Wave Devouring Propulsion System to Ocean Engineering

2012 ◽  
Author(s):  
Yutaka Terao ◽  
Shunji Sunahara
Keyword(s):  
Wind Turbine ◽  
Energy Absorption ◽  
Wave Energy ◽  
Type Systems ◽  
Propulsion System ◽  
Wave Power ◽  
Ocean Engineering ◽  
Hull Form ◽  
Wave Tank ◽  
Ocean Wind

A WDPS (wave devouring propulsion system) is a device that generates thrust directly from wave power and, at the same time, generates large damping forces. This phenomena is same as the thrust generation by the oscillating hydrofoil which are commonly used as the animal propulsion system such as the sea mammals or birds or fish propulsion. Relative flow acting on the hydrofoil generates thrust and damping force respectively. It is quite simple and consists of hydrofoils positioned in front of the bow. If the WDPS is installed in a ship hull, it can drive the hull (even against waves). One example is shown in Photo 1-1, the small WDPS vessel named Mermaid II, which succeeded in a historical trans-Pacific voyage from Hawaii to Japan (about 7800 km) in 2008 using only wave power. It proves that the WDPS may have some potential in the field of ocean engineering. In this paper we will propose two WDPS applications. One potential application is a midsized floating-type ocean wind turbine generator, which is composed of a single wind turbine on a catamaran hull with a set one-point mooring system. For this application, a new hull form and WDPS are developed based on Mermaid II. The hull needs to be stabilized because the ocean wind energy absorption efficiency is affected by the hull’s motion. Additionally, the mooring forces acting on the hull need to be reduced to keep the construction and power generation costs down. Therefore, the WDPS is installed in front of the hull to reduce/overcome the wave drifting force and the wind drag force. Another anticipated function of the WDPS is motion stabilization, particularly for pitch and roll motions. A suitable hull form is determined from wave tank experiments and is discussed herein. The other proposal is a multi-function WDPS that functions as both a wave energy absorption device and a wave thruster. Many hydrofoil-type wave energy conversion systems with forward propulsion have been proposed, but no advanced speed-type systems with a multi-function WDPS. A newly designed forced heave-pitch oscillator is also introduced, and tests are performed in the wave tank. The optimum hydrofoil control method in waves is discussed, and the thrust control is also tested and discussed.

Application of Wave Devouring Propulsion System for Ocean Engineering

2013 ◽  
Author(s):  
Yutaka Terao ◽  
Norimitsu Sakagami
Keyword(s):  
Data Acquisition ◽  
Wave Height ◽  
Autonomous Navigation ◽  
Data Acquisition System ◽  
Propulsion System ◽  
Acquisition System ◽  
Wave Power ◽  
Wave Direction ◽  
Ocean Engineering ◽  
Damping Force

A Wave Devouring Propulsion System (WDPS) generates thrust directly from wave power while simultaneously generating a strong damping force. A simple WDPS design consists of hydrofoils mounted below the bow of a vessel. If a WDPS is integrated with the hull of a vessel, then it can power the vessel forward, even against the wave direction itself. One example of a successful WDPS was installed on the vessel named Mermaid II, which completed a trans-Pacific voyage in 2008, traveling approximately 7,800 km from Hawaii to Japan using wave power alone. This success indicates that the WDPS has potential for use in the field of ocean engineering. As described in this paper, we intend to apply the WDPS to the small autonomous boat and to conduct sea trials. We designed and built an autonomous WDPS boat, developed a data acquisition system, and experimentally investigated its performance in Orida Bay. The experimentally obtained results indicate that the autonomous navigation of the WDPS boat is possible when the wave height is greater than 5–10 cm.

Characteristics of Hydrodynamics and Generating Output of the Offshore Floating Wave Energy Device “Mighty Whale”

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
Hiroyuki Osawa ◽  
Tsuyoshi Miyazaki ◽  
Shogo Miyajima
Keyword(s):  
Energy Absorption ◽  
Output Power ◽  
Wave Energy ◽  
Power Device ◽  
Hydrodynamic Characteristics ◽  
Wave Power ◽  
Water Tank ◽  
Power Devices ◽  
Turbine Generator ◽  
Generator System

In this paper, a new numerical calculation method is presented; it was developed for the analysis of the hydrodynamic characteristics of a floating, oscillating water column (OWC) type wave power device. The method is examined by comparing results calculated with the method with results of water tank experiments. The examination was concerned with the determination of hydrodynamic coefficients, characteristics of air pressure and water level in an air chamber, and characteristics of hull motion and wave energy absorption. The calculated results agreed with the results of water tank tests; the method presented adequately estimated the hydrodynamic characteristics of the floating OWC type wave power device, including the wave energy absorption effects. An estimation method is presented for the output power of a turbine-generator system. The method was developed for the design of the “Mighty Whale” turbine-generator system. Moreover, the method was assessed by comparing predictions with open sea test results. The mean value of the output power was estimated reasonably well. In conclusion, the estimation methods presented are useful for the design of floating OWC wave power devices. Such tools are useful for the designer interested in developing optimal wave power devices.

scholarly journals A Fundamental Study on Wave Energy Absorption Performance of the OWC Type Wave Power Absorbing buoy

2014 ◽  
Vol 131 (0) ◽  
pp. 113-118
Author(s):  
Mitsuhiro MASUDA ◽  
Shin IBARAKI ◽  
Kiyokazu MINAMI ◽  
Yutaro SASAHARA
Keyword(s):  
Energy Absorption ◽  
Wave Energy ◽  
Wave Power ◽  
Fundamental Study ◽  
Type Wave ◽  
Absorption Performance

Design and Construction of a 1/15th Scale Wave Tank Model of the Azura Commercial Wave Energy Converter

2019 ◽  
Author(s):  
Bradley A. Ling ◽  
Terry Lettenmaier ◽  
Matthew Fowler ◽  
Matthew Cameron ◽  
Anthony M. Viselli
Keyword(s):  
Wave Energy ◽  
Irregular Waves ◽  
Direct Drive ◽  
Ocean Engineering ◽  
Tank Model ◽  
Wave Tank ◽  
Energy Capture ◽  
Evaluation Of Performance ◽  
High Level ◽  
The University

Abstract The design of a 1/15th geometrically scaled wave tank model of the Azura™ commercial-scale wave energy device is presented. The objectives of the wave tank tests, conducted at the University of Maine Harlod Alfond Wind/Wave Ocean Engineering Lab (W2), included verification of the Azura’s energy capture in irregular waves, evaluation of performance in survival wave conditions, and testing of two advanced control algorithms. Due to the difficulty in properly Froude Scaling a hydraulic system, the model used a direct-drive rotary motor/generator power takeoff (PTO), with the dynamics of the hydraulic PTO included via a hardware-in-the-loop simulation. This PTO implementation led to additional design requirements being imposed on the model drivetrain. In addition to the model PTO design, the instrumentation design, structural design, and test plans are presented. The resulting model and PTO achieved a high level of controllability, and accurately emulated the dynamics of the hydraulic PTO of the full-scale Azura prototype.

scholarly journals Study on an Oscillating Water Column Wave Power Converter Installed in an Offshore Jacket Foundation for Wind-Turbine System Part I: Open Sea Wave Energy Converting Efficiency

2021 ◽  
Vol 9 (2) ◽  
pp. 133
Author(s):  
Hsien Hua Lee ◽  
Guan-Fu Chen ◽  
Hsiang-Yu Hsieh
Keyword(s):  
Wind Turbine ◽  
Water Column ◽  
Wind Power ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Offshore Wind ◽  
Wave Power ◽  
Oscillating Water Column ◽  
Energy Converter ◽  
Wind Turbine System

This study is focused on the wave energy converter of an oscillating water column (OWC) system that is integrated with a jacket type infrastructure applied for an offshore wind turbine system. In this way, electricity generation by both wind power and wave power can be conducted simultaneously to maximize the utilization of sustainable energy. A numerical analysis was performed in this research to model and simulate the airflow response and evaluate the converting efficiency of wave energy from an OWC system integrated with an offshore template structural system. The performance of the system including the generating airflow velocity, air-pressure in the chamber, generating power and then the converting efficiency of power from waves are all analyzed and discussed in terms of the variations of the OWC system’s geometrical parameters. The parameters under consideration include the exhale orifice-area of airflow, gate-openings of inflow water and the submerged chamber depth. It is found that from the analytical results the performance of the OWC wave energy converter is influenced by the dimensional parameters along with the design conditions of the local environment. After a careful design based on the in-situ conditions including water depth and wave parameters, an open OWC system can be successfully applied to the template structure of offshore wind power infrastructure as a secondary generating system for the multi-purpose utilization of the structure.

scholarly journals Total wave power absorption by a multi-float wave energy converter and a semi-submersible wind platform with a fast far field model for arrays

2021 ◽  
Author(s):  
Peter Stansby ◽  
Efrain Carpintero Moreno ◽  
Sam Draycott ◽  
Tim Stallard
Keyword(s):  
Wind Turbine ◽  
Wave Energy ◽  
Radiation Damping ◽  
Wave Energy Converter ◽  
Wave Power ◽  
Far Field ◽  
Energy Converter ◽  
Power Absorption ◽  
Wave Energy Converters ◽  
Total Wave

AbstractWave energy converters absorb wave power by mechanical damping for conversion into electricity and multi-float systems may have high capture widths. The kinetic energy of the floats causes waves to be radiated, generating radiation damping. The total wave power absorbed is thus due to mechanical and radiation damping. A floating offshore wind turbine platform also responds dynamically and damping plates are generally employed on semi-submersible configurations to reduce motion, generating substantial drag which absorbs additional wave power. Total wave power absorption is analysed here by linear wave diffraction–radiation–drag models for a multi-float wave energy converter and an idealised wind turbine platform, with response and mechanical power in the wave energy case compared with wave basin experiments, including some directional spread wave cases, and accelerations compared in the wind platform case. The total power absorption defined by capture width is input into a far field array model with directional wave spreading. Wave power transmission due a typical wind turbine array is only reduced slightly (less than 5% for a 10 × 10 platform array) but may be reduced significantly by rows of wave energy converters (by up to about 50%).

scholarly journals Hardware-in-the-Loop Validation of Model Predictive Control of a Discrete Fluid Power Power Take-Off System for Wave Energy Converters

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3668
Author(s):  
Anders H. Hansen ◽  
Magnus F. Asmussen ◽  
Michael M. Bech
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Wave Energy ◽  
Fluid Power ◽  
Wave Power ◽  
Reactive Control ◽  
Power Extraction ◽  
Wave Energy Converters ◽  
Extraction Algorithm ◽  
Energy Converters

Model predictive control based wave power extraction algorithms have been developed and found promising for wave energy converters. Although mostly proven by simulation studies, model predictive control based algorithms have shown to outperform classical wave power extraction algorithms such as linear damping and reactive control. Prediction models and objective functions have, however, often been simplified a lot by for example, excluding power take-off system losses. Furthermore, discrete fluid power forces systems has never been validated experimentally in published research. In this paper a model predictive control based wave power extraction algorithm is designed for a discrete fluid power power take-off system. The loss models included in the objective function are based on physical models of the losses associated with discrete force shifts and throttling. The developed wave power extraction algorithm directly includes the quantized force output and the losses models of the discrete fluid power system. The experimental validation of the wave power extraction algorithm developed in the paper shown an increase of 14.6% in yearly harvested energy when compared to a reactive control algorithm.

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