Effects of mooring systems on dynamic response of wave energy converter
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摘要:
目的 为了设计造价合理、性能高效的系泊系统,研究不同系泊系统对波能发电装置(WEC)的能量摄取(PTO)能力和定位性能的影响。 方法 选择一典型的两刚体点吸式WEC装置为研究对象,采用WEC-Sim和MoorDyn开源代码设计两类系泊系统,一类采用锚链,另一类采用锚链和聚酯缆绳所组成的混合缆。通过对这两类系泊系统进行时域分析计算,获得WEC位移响应以及PTO装置响应和系缆张力响应。 结果 结果表明:系泊系统对浮子位移响应的影响很小,但对Spar式底板的影响明显;对于针对线性阻尼型WEC,系泊系统对PTO响应的影响可以忽略不计;在工作海况下,混合缆系泊系统的张力比锚链系泊系统中同一位置处的更低。 结论 该研究可为波能发电装置的系泊设计提供参考。 -
关键词:
- 聚酯缆绳 /
- 波能发电装置模拟器(WEC-Sim) /
- MoorDyn /
- 波能发电装置 /
- 系泊系统
Abstract:Objectives Aiming at a mooring system design with cost-effectiveness and high performance for wave energy converter (WEC) , the effects of such systems on the capability of power take-off (PTO) system and positioning performance of WEC are investigated. Methods A two-body floating point absorber is chosen as the sample WEC. The open-source WEC-Sim and MoorDyn codes are used to design two types of mooring system for the WEC: one is a chain mooring system and the other is an integrated chain-rope (i.e., polyester fiber rope) mooring system. By performing time-domain analysis for the WEC with different mooring lines, the responses, such as WEC displacement, power take-off (PTO) and mooring line tension, are obtained respectively. Results The results show that, the effects of mooring systems on the displacement response of the floater are small, but these effects on the response of the spar body is obvious. For the WEC with a linear damper, these effects on the PTO response are negligible. Moreover, the line tensions of the integrated mooring system are lower than the corresponding tensions of the chain mooring system under the operational sea state. Conclusions The results of this study have reference value for the improved design of WEC mooring systems. -
Key words:
- polyester fiber ropes /
- WEC-sim /
- MoorDyn /
- wave energy converter (WEC) /
- mooring system
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表 1 两刚体点吸式波能发电装置的主要参数
Table 1. Main particulars of the two-body floating point absorber
参数 浮子 Spar式底板 外直径/m 20 6 质量/t 727.01 878.3 高度/m 5 38 重心坐标/m (0, 0, −0.72) (0, 0, −21.29) $ {I}_{xx}/ $$ (\mathrm{k}\mathrm{g}{\cdot \mathrm{m}}^{-2}) $ $ 2.09\times {10}^{7} $ $ 9.44\times {10}^{7} $ $ {I}_{yy}/ $$ (\mathrm{k}\mathrm{g}{\cdot \mathrm{m}}^{-2} )$ $ 2.13\times {10}^{7} $ $ 9.44\times {10}^{7} $ $ {I}_{{\textit{z}}{\textit{z}}}/ $$( \mathrm{k}\mathrm{g}{\cdot \mathrm{m}}^{-2}) $ $ 3.71\times {10}^{7} $ $ 2.85\times {10}^{7} $ $ {I}_{y{\textit{z}}}/ $$( \mathrm{k}\mathrm{g}{\cdot \mathrm{m}}^{-2} )$ $ 4.3\times {10}^{3} $ $ 2.18\times {10}^{5} $ 表 2 系缆主要参数
Table 2. Main particulars of mooring lines
参数 锚链系泊构型 混合缆系泊构型 系缆总长/ m 280 280 海底接触段的锚链长度/ m 240 30 连接沉子(重块)/个 − 1 聚酯缆绳/ m − 210 连接浮标/个 1 1 悬挂段的锚链长度/ m 40 40 表 3 系缆各组件参数
Table 3. Main particulars of components of mooring lines
系缆组件 参数 数值 锚链
(R4k4 studlink 型)直径/mm 76 空气中重量/(kg·m−1) 126.494 材料阻尼比 0.8 刚度/kN $ 5.83\times {10}^{5} $ 横向附加质量系数 1 切向附加质量系数 0 横向拖曳系数 1.6 切向拖曳系数 0.05 最小破断强度/kN 6 001.31 连接沉子(重块) 质量$ /\mathrm{k}\mathrm{g} $ 7 850 体积$ /{\mathrm{m}}^{3} $ 1 聚酯缆绳 直径/mm 144 空气中重量/(kg·m−1) 14.4 材料阻尼比 0.3 刚度/kN $ 2.26\times {10}^{4} $ 横向附加质量系数 1 切向附加质量系数 0 横向拖曳系数 1.6 切向拖曳系数 0.05 最小破断强度/kN 5 880 连接浮标 质量$ /\mathrm{k}\mathrm{g} $ 122 体积$ /{\mathrm{m}}^{3} $ 1 拖曳系数和浮子投影面积的乘积 0.5 附加质量系数 1 表 4 工作海况下波能发电装置动力响应的统计值
Table 4. Statistical data of the WEC under operational sea state
响应 系缆类别 平均值/m 标准差/m 最大值/m 最小值/m 浮子纵荡/m 锚链 0.002 1 0.244 9 0.594 5 −0.643 9 混合缆 0.003 8 0.250 5 0.614 5 −0.658 4 浮子垂荡/m 锚链 0.000 4 0.239 2 0.622 4 −0.607 2 混合缆 0.000 4 0.239 2 0.622 2 −0.607 1 浮子纵摇/(°) 锚链 0.000 2 0.007 2 0.017 4 −0.017 9 混合缆 0.000 2 0.007 1 0.017 0 −0.017 2 Spar式底板纵荡/m 锚链 0.003 1 0.100 7 0.255 8 −0.309 5 混合缆 0.003 8 0.250 5 0.614 5 −0.658 4 Spar式底板垂荡/m 锚链 −0.114 3 0.029 5 $ 4.79\times {10}^{-4} $ −0.184 2 混合缆 −0.197 9 0.036 2 $ 4.36\times {10}^{-7} $ −0.268 0 Spar式底板纵摇/(°) 锚链 0.000 2 0.007 2 0.017 4 −0.017 9 混合缆 0.000 2 0.007 1 0.017 0 −0.017 2 表 5 工作海况下波能摄取装置响应的统计值
Table 5. Statistical data of the PTO response under operational sea state
系泊类型 统计类型 相对位移/m 相对速度
/(m·s−1)${F}_{\rm{PTO} }/\rm{kN}$ PPTO
/(kN·m·s−1)锚链 最大值 0.692 0.546 653.67 358.329 平均值 0.115 6.29E-05 −0.075 50.570 最小值 −0.438 −0.545 −655.74 0 混合缆 最大值 0.777 0.546 653.67 358.29 平均值 0.199 0.000 276 −0.331 50.584 最小值 −0.353 −0.545 −655.71 0 表 6 工作海况下2种系泊系统的导缆孔处张力统计值
Table 6. Statistical data of line tensions at fairlead in two mooring systems under operational sea state
系泊类型 缆号 平均值/kN 标准差/kN 最大值/kN 最小值/kN 锚链 1 177.924 11.095 209.411 151.282 2 177.937 5.825 193.872 160.655 3 177.937 5.825 193.872 160.655 混合缆 1 47.045 0.761 49.230 44.997 2 47.036 0.354 48.090 46.047 3 47.036 0.354 48.090 46.047 表 7 极端海况下2种系缆的导缆孔处张力统计值
Table 7. Statistics of line tensions at fairlead in two mooring systems under extreme sea state
系泊类型 缆号 平均值/kN 标准差/kN 最大值/kN 最小值/kN 锚链 1 204.772 149.029 1 330.540 0.067 2 200.901 53.851 665.646 2.194 3 200.901 53.851 665.646 2.194 混合缆 1 48.114 9.552 122.511 18.331 2 47.614 4.999 69.317 31.902 3 47.614 4.999 69.317 31.902 -
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