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In this paper, the wave-induced motion characteristics of a floating pendulor are investigated numerically. A floating pendulor is a movable-body-type wave energy converter. This device consists of three main parts (floater, pendulum, and damping plates). In order to obtain the hydrodynamic coefficients and wave exciting forces acting on floating b...
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In this study, we investigated the hydrodynamic and energy conversion performance of a double-float wave energy converter (WEC) based on the linear theory of water waves. The generator power take-off (PTO) system is modeled as a combination of a linear viscous damping and a linear spring. Using the frequency domain method, the optimal damping coeff...
Citations
... The function of the double-freewheel is to rotate several wheels connected to the electric generator. This system was named a wave energy power generation-pendulum system (WEPG-PS) (Nam et al, 2011;Murakami et al, 2014). ...
... The promotion of new and renewable energy which originated from natural resource was conducted through the development of a wave energy power generationpendulum system (WEPG-PS) (Nam et al, 2011, Murakami et al, 2014. This study employed a mathematical physics concept to formulate the equation of motion through Euler-Lagrange Formalism (Roubicek, 2014). ...
... The computation process is used to prove both principles by increasing the value of the thrust force and decreasing friction. Besides, the numerical analysis for WPEG-SP in this study is appropriate with the other previous studies of the pendulum system in refs (Nam et al, 2011, Yu et al, 2016. ...
The wave energy power generation-pendulum system (WEPG-PS) is a four-wheeled instrument designed to convert wave power into electric energy. The first wheel is connected to the pendulum by a double freewheel, the second and third are ordinary wheels, while the fourth is a converter component that is axially connected to the electric generator. This design used the Euler-Lagrange formalism and Runge-Kutta method to examine an ideal dimension and determine the numerical solution of the equation of motion related to the rotation speed of the wheels. The result showed that the WEPG-PS' converter system rotated properly when its mass, length, and moment of inertia are 10 kg, 2.0 m, and 0.25 kgm2, respectively. This is in addition to when the radius of the first, second, third, and fourth wheels are 0.5, 0.4, 0.2, and 0.01 m, with inertia values of 0.005, 0.004, 0.003, and 0.1 kgm2. The converter system has the ability to rotate the fourth wheel, which acts as the handle of an electric generator at an angular frequency of approximately 500 - 600 rad/s. The converter system is optimally rotated when driven by a minimum force of 5 N and maximum friction of 0.05. Therefore, the system is used to generate electricity at an amplitude of 0.3 - 0.61 m, 220 V with 50 Hz. Besides, the lower rotation speed and frequency of the energy converter of the WEPG-PS (300 rad/s) and induction generator (50 Hz) were able to generate electric power of 7.5 kW. ©2020. CBIORE-IJRED. All rights reserved
... The function of the double-freewheel is to rotate several wheels connected to the electric generator. This system was named a wave energy power generation-pendulum system (WEPG-PS) (Nam et al, 2011;Murakami et al, 2014). ...
... The promotion of new and renewable energy which originated from natural resource was conducted through the development of a wave energy power generationpendulum system (WEPG-PS) (Nam et al, 2011, Murakami et al, 2014. This study employed a mathematical physics concept to formulate the equation of motion through Euler-Lagrange Formalism (Roubicek, 2014). ...
... The computation process is used to prove both principles by increasing the value of the thrust force and decreasing friction. Besides, the numerical analysis for WPEG-SP in this study is appropriate with the other previous studies of the pendulum system in refs (Nam et al, 2011, Yu et al, 2016. ...
... In WAB type wave-energy converters, relative motions between the activating body and the main body of the converter lead to power generation. Thus, the shape of the activating body and the methods used to connect the main body and the activating body are important to enhance the efficiency of power generation [7]. ...
The potential of wave power as an alternative energy resource is being studied to address problems associated with fossil fuel exhaustion and environmental pollution. In this paper, to improve the power generation efficiency of a floating-type wave-energy converter that has an activating body, the effects of the positions of a connecting bridge and different connecting methods between a main body and the activating body of the wave-energy converter were studied. In order to research the activating body’s motion characteristics that are caused by the changes of connecting bridge’s position and connecting methods; hinged or fixed connector, the wave-energy converter was modeled and simulated by using a commercial software. The moment and angular velocity of the axis of power generation were measured from the results of simulations and then the power outputs were calculated based on the moment and angular velocity. The outputs, which were analyzed under several regular wave conditions, were compared to each other.
... Recently, a floating pendulum WEC (see Fig. 2) consisting of floater, pendulum and damping plate was investigated [7,21], where the damping plate, which is a thin plate located behind the floater, is used to reduce the floater motion by introducing additional fluid forces. The numerical results of Nam et al. [22] showed that the efficiency of the floating pendulum WEC is less than that of the pendulum WEC whereas the experimental flume results of Murakami et al. [23] showed that the maximum primary conversion efficiency and the maximum generating efficiency at the optimal load are 98% and about 23%, respectively. The development of a new WEC to capture both kinetic energy and potential energy by utilizing the advantages of raft-type and pendulum-type WECs is therefore timely and relevant in the context of other recent works. ...
... Recently, the Korea Research Institute of Ship and Ocean (KRISO) in Daejeon, Korea, has investigated a floating pendulum WEC by numerically studying its wave-induced motion characteristics (Nam, 2012). Furthermore, 1/20 scale-model tests were performed to analyze the wave responses of the water chamber and the motions of the floating device in a two-dimensional wave tank (Park, 2011). The addition of motion-reduction structures to the WEC to change its size, shape, and position resulted in satisfactory motion-reduction performance (Park, 2013). ...
We comparatively investigated wave-induced motions of two floating pendulum wave energy converters (WECs): one designed to reduce motion response via a damping plate and the other designed to reduce motion response via a large water-plane area. The motion responses were compared through model tests under operational and survival wave conditions and were numerically analyzed through a higher-order boundary element method (HOBEM) using the wave Green function. From experimental and numerical data, 6-DOF motion responses were compared under survival conditions. The WEC efficiency was estimated from the relative angular motions of the pendulum. An optimal WEC design was proposed by considering seakeeping performance and efficiency.
... Shin et al., 2005;Kyoung et al., 2006;Ryu et al., 2007;Hong et al., 2007;Nam et al., 2011;Park et al., 2011). 그러나 파력발전을 실용화하기 위 해서는 발전이 가능한 파력 에너지 부존량(WEP; Wave Energy Potential)의 시간적·공간적 변동 양상과 분포 특성이 파악되어야 한다. ...
In this study, the wave energy potential (WEP) was evaluated using the wave data measured at nine stations along the Korean east coast and compared with the results of previous studies. Along the Korean east coast, seasonal variations in the WEP were around 6.4 kW/m in winter and 1.2 kW/m in summer, greater than spatial variations of 2.5~4.3 kW/m. In most stations, the wave power during June to July were shown to be smallest. The estimated annual average WEP was greatest in the Mukho and Jukbyeon stations located in the middle of the Korean east coast at around 4.3 kW/m, and smallest in the Jinha station at around 2.5 kW/m. The results found using the previous hindcast data showed WEP having a tendency to decrease from south to north. However, in this study, the WEP showed a tendency of being greatest in the middle of the Korean east coast and decreasing in both north and south directions.
The present study experimentally considers dynamic performance of large floating wave-offshore hybrid power generation platform in extreme conditions. In order to evaluate the motion performance of the large floating hybrid power generation platform, 1/50 scaled model was manufactured. A mooring line was also manufactured, and free-decay and static pull-out tests were carried out to check the mooring model. A mooring line table was introduced to satisfy the water depth, and environmental conditions were checked. Motion responses in regular waves were measured and complicated environmental conditions including wave, wind, and current were applied to see the dynamic performance in extreme/survival conditions. Maximum motion and acceleration were judged following the design criteria, and maximum offset and mooring tension were also checked based on the rule. The characteristics of hybrid power generation platform are discussed based on these data.
The floating pendulum type wave energy converter device, a type of rotating body wave energy converter, directs wave energy into the water chamber of the floating body, converting the energy thereof into the alternating motion of the pendulum to generate electricity. The pendulum-type energy converter uses a pendulum plate in direct transduction, converting the potential and kinetic energy of waves into mechanical energy, with the advantage of high conversion efficiency. However, as the motion is directly exposed to wave load, there is a need to examine structural stability against various loads. In this study, structural analysis was performed on the primary transduction system under various conditions. Static/dynamic structural analysis was performed under wave load, and impact analysis was performed between the pendulum plate and water chamber. The commercial software Ansys was used for numerical analysis. Results of analysis showed the stress distribution on each part, based on which the safety of each part was evaluated. Copyright © 2014 by the International Society of Offshore and Polar Engineers (ISOPE).
