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1
Content available Study on the dynamic response of deep-sea trawlers in sea trials
Xu Qingchao, Xie Yonghe, Cai Hao, Gong Xiwu, Li Detang, Wei Wang, Jia Panpan
Polish Maritime Research
|
2023
|
nr 1
25--32
EN
The increasing use of automation in fishing vessels has improved trawling efficiency while directly affecting the fishing capacity and cost of fishing vessels. Among the various influencing factors, warp tension and warp length can be varied to automatically balance the retraction and release of warp control. We combined the two parameters and independently designed and developed the key equipment for fishing vessels—the warp dynamometer and meter counter—and control software. The accuracy of the warp tension and length measurements was improved. The designed equipment was applied to sea trials under different working conditions, and the test data records were exported. Next, filtered time-domain graphs of the required parameters were plotted through complex Fourier transform, first-order lowpass filtering, and inverse Fourier transform. The results of data processing using various parameters were compared and analysed to determine the variation trends of the parameters and verify the effects of their balance control. The results indicated that using an automatic balance control system that combines warp tension and warp length can be effective for the fishing operation of offshore double-deck trawlers. In addition, first-order low-pass filtering can be used to filter complex warp tension data. This study also determined the relationship between warp tension and experimental parameters such as warp length and ship speed during the release of control. After the balance control of warp tension and warp length, the net mouth area increased by 30.7% and 36.5%, respectively, and the fishing efficiency of the vessel improved considerably.
2
Content available Study on dynamic response of offshore wind turbine structure under typhoon
Li Junlai, Wu Weiguo, Wei Yu, Shu Yu, Lu Zhiqiang, Lai Wenbin, Jia Panpan, Zhao Cheng, Xie Yonghe
Polish Maritime Research
|
2022
|
nr 1
34--42
EN
Floating offshore wind turbines are easily affected by typhoons in the deep sea, which may cause serious damage to their structure. Therefore, it is necessary to study further the dynamic response of wind turbine structures under typhoons. This paper took the 5MW floating offshore wind turbine developed by the National Renewable Energy Laboratory (NREL) as the research object. Based on the motion theory of platforms in waves, a physical model with a scale ratio of 1:120 was established, and a hydraulic cradle was used to simulate the effect of waves on the turbines. The dynamic response characteristics of offshore wind turbines under typhoons are systematically studied. The research results clarified that the turbine structure is mainly affected by wave loads under typhoons, and its motion response reaches its maximum value under the action of extreme wave loads. The research results of this paper can provide reference value for the design of offshore wind turbine structures under typhoons.
3
Content available Numerical study on the optimization of hydrodynamic performance of oscillating buoy wave energy converter
Lai Wenbin, Xie Yonghe, Li Detang
Polish Maritime Research
|
2021
|
nr 1
48--58
EN
The oscillating buoy wave energy converter (OBWEC) captures wave energy through the undulating movement of the buoy in the waves. In the process of capturing wave energy, the hydrodynamic performance of the buoy plays an important role. This paper designed the “Haida No. 1” OBWEC, in which the buoy adopts a form of swinging motion. In order to further improve the hydrodynamic performance of the buoy, a 2D numerical wave tank (NWT) model is established using ADINA software based on the working principle of the device. According to the motion equation of the buoy in the waves, the influence of the buoy shape, arm length, tilt angle, buoy draft, buoy width, wave height and Power Take-off (PTO) damping on the hydrodynamic performance of the buoy is studied. Finally, a series of physical experiments are performed on the device in a laboratory pool. The experimental results verify the consistency of the numerical results. The research results indicate that the energy conversion efficiency of the device can be improved by optimizing the hydrodynamic performance of the buoy. However, the absorption efficiency of a single buoy for wave energy is limited, so it is very difficult to achieve full absorption of wave energy.
4
Content available Simulation and experimental study of hydraulic cylinder in oscillating float-type wave energy converter
Lai Wenbin, Li Detang, Xie Yonghe
Polish Maritime Research
|
2020
|
nr 2
30--38
EN
Hydraulic cylinders play a vital role in the energy output (PTO) system of an oscillating float-type wave Energy converter, whose function is to convert the mechanical energy captured by the float from the waves into hydraulic energy. The performance of the hydraulic cylinder determines the conversion efficiency of mechanical energy to hydraulic energy in the system; therefore, it is necessary to study the working mechanism of the hydraulic cylinder. This paper takes a self-developed oscillating float-type wave energy converter as the research object, and studies the working mechanism of its hydraulic cylinder, and uses the linear analysis method to derive the critical self-excited vibration curve of the hydraulic cylinder. In addition, the effects of the external load, hydraulic cylinder load mass, stroke length, spring stiffness and piston area on the performance of the hydraulic cylinder were studied by AMESim simulation software. According to the simulation results, a physical model of the hydraulic cylinder is established. Finally, the physical model is tested in a hydrodynamic pool. The test results show that the hydraulic cylinder can stably and efficiently convert mechanical energy into hydraulic energy even under small waves, thus verifying the rationality of the hydraulic cylinder design.
5
Content available Analysis of the dynamic response of offshore floating wind power platforms in waves
Li Junlai, Xie Yonghe, Wu Weiguo, Zhang Chi
Polish Maritime Research
|
2020
|
nr 4
17--25
EN
Floating wind power platforms are in constant motion due to waves when deployed at sea. This motion directly affects the stability and safety of the platform. Therefore, it is very important to study the laws governing the platform’s dynamic response. In this paper, the dynamic characteristics of an offshore floating wind power platform were analysed under nine different sets of operating conditions using a numerical calculation method. Following this, a scaled 1:50 platform model was tested in a tank. Model tests were carried out with different wave conditions, and dynamic response data for the platform were measured and analysed. The hydrodynamic variation rules of floating wind power generation platform in waves were obtained. Some effective measures for maintain the stability and safety of wind power platforms are put forward that can provide a reference for dynamic stability research and the design of floating wind power platforms in the future.
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