二阶斯托克斯非线性潮波对潮汐贯流式水轮机性能的影响
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摘要
双向贯流式水轮机在潮汐能开发中的应用广泛。在海洋波流条件影响下,潮汐能机组在反向运行过程中的水动力性能变化是潮汐能机组研发过程中需要考虑的重要问题。该文采用二阶斯托克斯非线性潮波对海洋潮波来流进行了模拟,建立了二阶斯托克斯非线性潮波边界下的潮汐贯流式水轮机性能分析模型并验证了模型的可靠性。以该模型为基础,采用CFD方法,对某一潮汐贯流式水轮机在反向运行时的内部流动进行数值仿真,重点研究了动态波流边界对贯流式水轮机反向运行时水力特性的影响。研究结果表明:1)考虑波流耦合作用时,潮波与坝体发生碰撞后损失了大部的动能,形成的反射波流,覆盖下一个波峰前的气体形成大气泡进入海洋内部;2)来流潮波与坝体壁面反射潮波的相互作用是形成潮汐贯流式水轮机取水口处夹气涡的原因,形成的夹气涡在液面下旋转前进流入内流场黏附于流道上侧,压缩流场过流面积,形成了一个低压低速的夹气涡流动带,从而改变内流场流动分布和贯流机组的特性;3)动态波流的作用使得潮汐贯流式水轮机转轮叶片上的受力呈现较大幅度波动,叶片受力的低频幅值会随着夹气涡的发展而逐渐增大。同时,在波流影响下机组出力的波动幅度达到3.86%,远高于无波流作用下的不足1%,从而导致电能质量下降。
As a form of ocean energy, tidal energy is extremely abundant in oceans, with the characteristics of being clean, reliable, predictable and renewable. In the development of tidal energy, a bi-directional tubular turbine has been widely adopted for power generation. The tubular turbine converts the energy extracted from tides into mechanical energy, and further into useful electricity. The tubular turbine has been well designed suitable for generating power from both flow directions, in order to take full use of the tidal energy not only in the flood tide state but also during the ebb tide state. However, the operation condition of the tubular turbine will be definitely affected by the movement of the wave caused by tide, especially for the reverse power generation direction in which the flow direction is from the ocean to the turbine installed in the hydraulic dam. In this case, under the influence of ocean wave current conditions, the change of hydrodynamic performance during the reverse operation of tidal energy units is an important issue to be considered during the development of tidal energy units. In this paper, the nonlinear second-order Stokes wave law was used to simulate the ocean tide flow, and the second-order Stokes wave formula ocean wave flow condition model has been established based on actual oceanic flow conditions. The chosen tubular turbine had 4 runner blades, with a hub ratio of 0.38 and a runner diameter of 2.5 m. The turbine consisted of an intake part with body, guide vanes, runner and straight draft tube. In order to discrete the computational domains, the grid generation tool ICEM CFD was used to generate high quality structure grids. The number of grids chosen for simulations was approximately 6.5 million, after a grid-independent study with the hydraulic efficiency of the turbine being the examined criterion. The RNG k-?. turbulence model was chosen to close the time-averaged N-S equations. Transient simulations with considering the effect of the ocean wave on the flow have been realized with the help of ANSYS CFX, with a VOF(volume of fluid) model being adopted in the ocean domain to simulate the free surface of the boundary between the liquid and air. Based on the numerical results, the internal flow characteristics of a tidal energy turbine tune turbine in reverse running under dynamic wave flow boundary conditions were studied. In addition, the influence mechanism of tidal wave on the stability of the tubular turbine operation was discussed in detail. The results showed that: 1) Considering the coupling of wave and flow, most of the kinetic energy was lost after the tidal wave collided with the dam, and the reflected wave flow was therefore formed, which covered the air before the next peak of the wave and produces bubbles entering into the interior of the ocean. 2) The interaction between the incoming tidal wave and the reflected tidal wave on the wall of the dam was the cause of the vortex at the water intake of the tidal tubular turbine. The formed vortex was rotated under the liquid surface and flows into the internal flow field. The upper side of the flow path compressed the flow area to form a low-pressure and low-speed vortex region, which changed the flow distribution of the internal flow field and the characteristics of the tubular turbine. 3) The action of the dynamic wave caused the force on the rotor blades of the tidal tubular turbine to fluctuate greatly, and the low-frequency amplitude of the blade force increases with the development of the air-entraining vortex. At the same time, the fluctuation of unit output under the influence of wave current reached 3.86%, which was much higher than that of less than 1% under no-wave condition, resulting in a decline in power quality.
As a form of ocean energy, tidal energy is extremely abundant in oceans, with the characteristics of being clean, reliable, predictable and renewable. In the development of tidal energy, a bi-directional tubular turbine has been widely adopted for power generation. The tubular turbine converts the energy extracted from tides into mechanical energy, and further into useful electricity. The tubular turbine has been well designed suitable for generating power from both flow directions, in order to take full use of the tidal energy not only in the flood tide state but also during the ebb tide state. However, the operation condition of the tubular turbine will be definitely affected by the movement of the wave caused by tide, especially for the reverse power generation direction in which the flow direction is from the ocean to the turbine installed in the hydraulic dam. In this case, under the influence of ocean wave current conditions, the change of hydrodynamic performance during the reverse operation of tidal energy units is an important issue to be considered during the development of tidal energy units. In this paper, the nonlinear second-order Stokes wave law was used to simulate the ocean tide flow, and the second-order Stokes wave formula ocean wave flow condition model has been established based on actual oceanic flow conditions. The chosen tubular turbine had 4 runner blades, with a hub ratio of 0.38 and a runner diameter of 2.5 m. The turbine consisted of an intake part with body, guide vanes, runner and straight draft tube. In order to discrete the computational domains, the grid generation tool ICEM CFD was used to generate high quality structure grids. The number of grids chosen for simulations was approximately 6.5 million, after a grid-independent study with the hydraulic efficiency of the turbine being the examined criterion. The RNG k-?. turbulence model was chosen to close the time-averaged N-S equations. Transient simulations with considering the effect of the ocean wave on the flow have been realized with the help of ANSYS CFX, with a VOF(volume of fluid) model being adopted in the ocean domain to simulate the free surface of the boundary between the liquid and air. Based on the numerical results, the internal flow characteristics of a tidal energy turbine tune turbine in reverse running under dynamic wave flow boundary conditions were studied. In addition, the influence mechanism of tidal wave on the stability of the tubular turbine operation was discussed in detail. The results showed that: 1) Considering the coupling of wave and flow, most of the kinetic energy was lost after the tidal wave collided with the dam, and the reflected wave flow was therefore formed, which covered the air before the next peak of the wave and produces bubbles entering into the interior of the ocean. 2) The interaction between the incoming tidal wave and the reflected tidal wave on the wall of the dam was the cause of the vortex at the water intake of the tidal tubular turbine. The formed vortex was rotated under the liquid surface and flows into the internal flow field. The upper side of the flow path compressed the flow area to form a low-pressure and low-speed vortex region, which changed the flow distribution of the internal flow field and the characteristics of the tubular turbine. 3) The action of the dynamic wave caused the force on the rotor blades of the tidal tubular turbine to fluctuate greatly, and the low-frequency amplitude of the blade force increases with the development of the air-entraining vortex. At the same time, the fluctuation of unit output under the influence of wave current reached 3.86%, which was much higher than that of less than 1% under no-wave condition, resulting in a decline in power quality.
引文
[1]富旭平,郑峰.灯泡贯流式水轮机效率问题[J].水电能源科学,2008(6):132-133.Fu Xuping,Zheng Feng.Study on efficiency of bulb turbine[J].Water Resources and Power,2008(6):132-133.(in Chinese with English abstract)
[2]刘胜柱,赵亚萍.3叶片贯流水轮机内部流动数值与试验研究[C]//中国水力发电工程学会,2013.Liu Shengzhu,Zhao Yaping.Numerical and experimental research on internal flow of three-blades[C]//Turbine China Hydroelectric Engineering Society,2013.(in Chinese with English abstract)
[3]钱忠东,魏巍,冯晓波.灯泡贯流式水轮机全流道压力脉动数值模拟[J].水力发电学报,2014,33(4):242-249.Qian Zhongdong,Wei Wei,Feng Xiaobo.Numerical simulation of pressure pulsation in the whole flow passage of bulb turbine[J].Proceedings of the Society of Hydroelectric Power,2014,33(4):242-249.(in Chinese with English abstract)
[4]Thaithacha Sudsuansee,Udomkiat Nontakaew.Simulation of leading edge cavitation on bulb turbine[J].Songklanakarin Journal of Science and Technology,2011(1):51-60.
[5]刘延泽,常近时.重力场对灯泡贯流式水轮机流场分析及水力性能评估的影响[J].水利学报,2008,39(1):96-102.Liu Yanze,Chang Jinshi.Influence of gravity on flow field analysis and hydraulic performance evaluation of bulb turbine[J].Journal of Hydraulic Engineering,2008,39(1):96-102.(in Chinese with English abstract)
[6]王正伟,杨校生,肖业祥.新型双向潮汐发电水轮机组性能优化设计[J].排灌机械工程学报,2010(5):417-421.Wang Zhengwei,Yang Xiaosheng,Xiao Yexiang.Hydraulic performance optimization of bidirectional tidal power turbine[J].Journal of Drainage and Irrigation Machinery Engineering,2010(5):417-421.(in Chinese with English abstract)
[7]王正伟,周凌九,陈炎光,等.灯泡贯流式水轮机水力损失分析[J].大电机技术,2004(5):40-43.Wang Zhengwei,Zhou Liangjiu,Chen Yanguang,et al Hydraulic loss analysis in bulb turbine[J].Large Electric Machine and Hydraulic Turbine,2004(5):40-43.(in Chinese with English abstract)
[8]赵亚萍.轴(贯)流式水轮机性能研究与优化[D].西安:西安理工大学,2014.Zhao Yaping.Performance Analysis and Optimization Design for Kaplan and Bulb Turbines[D].Xi’an:Xi’an University of Technology,2014.(in Chinese with English abstract)
[9]Soohwang A,Xiao Yexiang,Wang Zhengwei,et al.Numerical prediction on the effect of free surface vortex on intake flow characteristics for tidal power station[J].Renewable Energy,2017,101:617-628.
[10]Soohwang A,Xiao Yexiang,Wang Zhengwei,et al.Performance prediction of a prototype tidal power turbine by using a suitable numerical model[J].Renewable Energy,2017,113:293-302.
[11]Lane G L,Rigby G D,Evans G M.Pressure distribution on the surface of Rushton turbine blades-experimental measurement and prediction by CFD[J].Journal of Chemical Engineering of Japan,2001,34(5):613-620.
[12]李琪飞,张毅鹏,敏政,等.变工况下贯流式水轮机叶片形变分析[J].兰州理工大学学报,2015,41(2):61-64.Li Qifei,Zhang Yiping,Min Zheng et al.Deformation analysis of tubular turbine blades under variable working condition[J].Journal of Lanzhou University of Technology,2015,41(2):61-64.(in Chinese with English abstract)
[13]郑小波,王玲军,翁凯.基于双向流固耦合的贯流式水轮机动力特性分析[J].农业工程学报,2016,32(4):78-83.Zheng Xiaobo,Wang Lingjun,Weng Kai.Dynamic characteristics analysis of tubular turbine based on bidirectional fluid-solid coupling[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2016,32(4):78-83.(in Chinese with English abstract)
[14]王正伟,阎宗国,彭光杰,等.一种六工况双向潮汐发电水轮机:CN202140236U[P].2012-02-08.
[15]李正贵,任明月,杨逢瑜.水位变化对贯流式水轮机组出力及稳定性影响[J].水力发电学报,2017,36(7):74-82.Li Zhenggui,Ren Mingyue,Yang Fengyu.Effects of changes in water levels on power output and stability of tubular turbine sets[J].Journal of Hydroelectric Engineering,2017,36(7):74-82.(in Chinese with English abstract)
[16]王树青,梁丙臣.海洋工程波浪力学[M].青岛:中国海洋大学出版社,2013.
[17]赵理工,梁书秀.波流耦合作用下台风浪的模拟[J].中国水运,2016,16(6):100-103.Zhao Ligong,Liang Shuxiu.Wave Simulation under Wave-Current Coupling[J].China Water Transport,2016,16(6):100-103.(in Chinese with English abstract)
[18]Luo Yongyao,Wang Zhengwei,Xiao Yexiang,et al.Optimization of the runner for extremely low head bidirectional tidal bulb turbine[J].Energies,2017,10(6):787-799.
[19]Luo Yongyao,Wang Zhengwei,Xin Liu,et al.Numerical prediction of pressure pulsation for a low head bidirectional tidal bulb turbine[J].Energies,2015,89:730-738.
[20]邹志利.海岸动力学[M].北京:人民交通出社,2009.
[21]王福军.计算流体力学-CFD软件原理与应用[M].北京:清华大学出版社,2004.
[22]吴玉林,刘树红,钱忠东.水力机械计算流体动力学[M].北京:中国水利水电出版社,2006.
[23]刘树红,吴玉林.水力机械流体动力学基础[M].北京:中国水利水电出版社,2007.
[24]王福军.流体机械旋转湍流计算模型研究进展[J].农业机械学报,2016,47(2):1-14.Wang Fujun.Research progress of computational model for rotating turbulent flow in fluid machinery[J].Transactions of the Chinese Society for Agricultural Machinery,2016,47(2):1-14.(in Chinese with English abstract)
[25]IEC-60193.Hydraulic turbines,storage pumps and pump-turbines model acceptance tests[S].
[26]杨爱菊,杨丽洁,李红星,等.海洋能之潮汐电站开发技术概要-浅析潮汐电站选址基本要素[J].西北水电,2010(2):89-95.Yang Aiju,Yang Lijie,Li Hongxing,et al.An overview of technology for development of tidal power stations-Analysis of basic elements for site selection of tidal power stations[J].Northwest Hydropower,2010(2):89-95.(in Chinese with English abstract)
[27]刘莎莎,顾煜炯,惠万馨,等.基于边界造波法的波浪数值模拟[J].可再生能源,2013,31(2):100-103.Liu Shasha,Gu Yujiong,Hui Wanxin,et al.Wave numerical simulation based on wave-generation method of defining inlet boundary conditions[J].Renewable Energy Resources,2013,31(2):100-103.(in Chinese with English abstract)
[28]于龙基,杨森,张华昌,等.弧形防浪墙的迎浪面波压力数值模拟[J].水运工程,2017(11):29-35.Yu Longji,Yang Sen,Zhang Huachang,et al.Numerical simulation of wave pressure on upright section of arc crown wall[J].Port and Waterway Engineering,2017(11):29-35.(in Chinese with English abstract)
[29]刘师辉,胡金鹏.基于Fluent的数值造波及其对水平板冲击作用初步研究[J].广东造船,2017,36(6):13-16.Liu Shihui,Hu Jinpeng.A preliminary study on numerical waves and its impact on horizontal plate with fluent[J].Guangdong Shipbuilding,2017,36(6):13-16.(in Chinese with English abstract)
[30]刘秀丽,段梦兰,高攀,等.基于OpenFOAM的数值波浪水槽研究[J].复旦学报:自然科学版,2015,54(3):373-378.Liu Xiuli,Duan Menglan,Gao Pan,et al.Development of numerical wave flumes based on openfoam[J].Journal of Fudan University:Natural Science,2015,54(3):373-378.(in Chinese with English abstract)
[31]乐清湾水利开发委员会.江厦潮汐试验电站:1969-2005[M].北京:中国电力出版社,2008.
[2]刘胜柱,赵亚萍.3叶片贯流水轮机内部流动数值与试验研究[C]//中国水力发电工程学会,2013.Liu Shengzhu,Zhao Yaping.Numerical and experimental research on internal flow of three-blades[C]//Turbine China Hydroelectric Engineering Society,2013.(in Chinese with English abstract)
[3]钱忠东,魏巍,冯晓波.灯泡贯流式水轮机全流道压力脉动数值模拟[J].水力发电学报,2014,33(4):242-249.Qian Zhongdong,Wei Wei,Feng Xiaobo.Numerical simulation of pressure pulsation in the whole flow passage of bulb turbine[J].Proceedings of the Society of Hydroelectric Power,2014,33(4):242-249.(in Chinese with English abstract)
[4]Thaithacha Sudsuansee,Udomkiat Nontakaew.Simulation of leading edge cavitation on bulb turbine[J].Songklanakarin Journal of Science and Technology,2011(1):51-60.
[5]刘延泽,常近时.重力场对灯泡贯流式水轮机流场分析及水力性能评估的影响[J].水利学报,2008,39(1):96-102.Liu Yanze,Chang Jinshi.Influence of gravity on flow field analysis and hydraulic performance evaluation of bulb turbine[J].Journal of Hydraulic Engineering,2008,39(1):96-102.(in Chinese with English abstract)
[6]王正伟,杨校生,肖业祥.新型双向潮汐发电水轮机组性能优化设计[J].排灌机械工程学报,2010(5):417-421.Wang Zhengwei,Yang Xiaosheng,Xiao Yexiang.Hydraulic performance optimization of bidirectional tidal power turbine[J].Journal of Drainage and Irrigation Machinery Engineering,2010(5):417-421.(in Chinese with English abstract)
[7]王正伟,周凌九,陈炎光,等.灯泡贯流式水轮机水力损失分析[J].大电机技术,2004(5):40-43.Wang Zhengwei,Zhou Liangjiu,Chen Yanguang,et al Hydraulic loss analysis in bulb turbine[J].Large Electric Machine and Hydraulic Turbine,2004(5):40-43.(in Chinese with English abstract)
[8]赵亚萍.轴(贯)流式水轮机性能研究与优化[D].西安:西安理工大学,2014.Zhao Yaping.Performance Analysis and Optimization Design for Kaplan and Bulb Turbines[D].Xi’an:Xi’an University of Technology,2014.(in Chinese with English abstract)
[9]Soohwang A,Xiao Yexiang,Wang Zhengwei,et al.Numerical prediction on the effect of free surface vortex on intake flow characteristics for tidal power station[J].Renewable Energy,2017,101:617-628.
[10]Soohwang A,Xiao Yexiang,Wang Zhengwei,et al.Performance prediction of a prototype tidal power turbine by using a suitable numerical model[J].Renewable Energy,2017,113:293-302.
[11]Lane G L,Rigby G D,Evans G M.Pressure distribution on the surface of Rushton turbine blades-experimental measurement and prediction by CFD[J].Journal of Chemical Engineering of Japan,2001,34(5):613-620.
[12]李琪飞,张毅鹏,敏政,等.变工况下贯流式水轮机叶片形变分析[J].兰州理工大学学报,2015,41(2):61-64.Li Qifei,Zhang Yiping,Min Zheng et al.Deformation analysis of tubular turbine blades under variable working condition[J].Journal of Lanzhou University of Technology,2015,41(2):61-64.(in Chinese with English abstract)
[13]郑小波,王玲军,翁凯.基于双向流固耦合的贯流式水轮机动力特性分析[J].农业工程学报,2016,32(4):78-83.Zheng Xiaobo,Wang Lingjun,Weng Kai.Dynamic characteristics analysis of tubular turbine based on bidirectional fluid-solid coupling[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2016,32(4):78-83.(in Chinese with English abstract)
[14]王正伟,阎宗国,彭光杰,等.一种六工况双向潮汐发电水轮机:CN202140236U[P].2012-02-08.
[15]李正贵,任明月,杨逢瑜.水位变化对贯流式水轮机组出力及稳定性影响[J].水力发电学报,2017,36(7):74-82.Li Zhenggui,Ren Mingyue,Yang Fengyu.Effects of changes in water levels on power output and stability of tubular turbine sets[J].Journal of Hydroelectric Engineering,2017,36(7):74-82.(in Chinese with English abstract)
[16]王树青,梁丙臣.海洋工程波浪力学[M].青岛:中国海洋大学出版社,2013.
[17]赵理工,梁书秀.波流耦合作用下台风浪的模拟[J].中国水运,2016,16(6):100-103.Zhao Ligong,Liang Shuxiu.Wave Simulation under Wave-Current Coupling[J].China Water Transport,2016,16(6):100-103.(in Chinese with English abstract)
[18]Luo Yongyao,Wang Zhengwei,Xiao Yexiang,et al.Optimization of the runner for extremely low head bidirectional tidal bulb turbine[J].Energies,2017,10(6):787-799.
[19]Luo Yongyao,Wang Zhengwei,Xin Liu,et al.Numerical prediction of pressure pulsation for a low head bidirectional tidal bulb turbine[J].Energies,2015,89:730-738.
[20]邹志利.海岸动力学[M].北京:人民交通出社,2009.
[21]王福军.计算流体力学-CFD软件原理与应用[M].北京:清华大学出版社,2004.
[22]吴玉林,刘树红,钱忠东.水力机械计算流体动力学[M].北京:中国水利水电出版社,2006.
[23]刘树红,吴玉林.水力机械流体动力学基础[M].北京:中国水利水电出版社,2007.
[24]王福军.流体机械旋转湍流计算模型研究进展[J].农业机械学报,2016,47(2):1-14.Wang Fujun.Research progress of computational model for rotating turbulent flow in fluid machinery[J].Transactions of the Chinese Society for Agricultural Machinery,2016,47(2):1-14.(in Chinese with English abstract)
[25]IEC-60193.Hydraulic turbines,storage pumps and pump-turbines model acceptance tests[S].
[26]杨爱菊,杨丽洁,李红星,等.海洋能之潮汐电站开发技术概要-浅析潮汐电站选址基本要素[J].西北水电,2010(2):89-95.Yang Aiju,Yang Lijie,Li Hongxing,et al.An overview of technology for development of tidal power stations-Analysis of basic elements for site selection of tidal power stations[J].Northwest Hydropower,2010(2):89-95.(in Chinese with English abstract)
[27]刘莎莎,顾煜炯,惠万馨,等.基于边界造波法的波浪数值模拟[J].可再生能源,2013,31(2):100-103.Liu Shasha,Gu Yujiong,Hui Wanxin,et al.Wave numerical simulation based on wave-generation method of defining inlet boundary conditions[J].Renewable Energy Resources,2013,31(2):100-103.(in Chinese with English abstract)
[28]于龙基,杨森,张华昌,等.弧形防浪墙的迎浪面波压力数值模拟[J].水运工程,2017(11):29-35.Yu Longji,Yang Sen,Zhang Huachang,et al.Numerical simulation of wave pressure on upright section of arc crown wall[J].Port and Waterway Engineering,2017(11):29-35.(in Chinese with English abstract)
[29]刘师辉,胡金鹏.基于Fluent的数值造波及其对水平板冲击作用初步研究[J].广东造船,2017,36(6):13-16.Liu Shihui,Hu Jinpeng.A preliminary study on numerical waves and its impact on horizontal plate with fluent[J].Guangdong Shipbuilding,2017,36(6):13-16.(in Chinese with English abstract)
[30]刘秀丽,段梦兰,高攀,等.基于OpenFOAM的数值波浪水槽研究[J].复旦学报:自然科学版,2015,54(3):373-378.Liu Xiuli,Duan Menglan,Gao Pan,et al.Development of numerical wave flumes based on openfoam[J].Journal of Fudan University:Natural Science,2015,54(3):373-378.(in Chinese with English abstract)
[31]乐清湾水利开发委员会.江厦潮汐试验电站:1969-2005[M].北京:中国电力出版社,2008.