混流式水轮机高于额定水头下叶道涡的研究
发布时间：2019-04-12 14:10
【摘要】：当混流式水轮机在偏离最优工况,高于额定水头下运行时,水流在转轮叶片进口靠近上冠处形成了部分脱流,产生叶道涡,并从叶片之间流出,影响水轮机的内部流场,叶道涡发展到一定程度时就会引起水轮机的水力振动,当振动超过允许值,尤其是长期处于振动状态,甚至与水轮机零部件产生共振时,会严重威胁到水电站机电设备的稳定安全运行和工作人员的人身安全。 导水机构作为混流式水轮机重要的过流部件。水流从蜗壳及固定导叶流出,通过绕流导叶,水流的流态发生改变,影响着转轮进口处水流速度的大小和方向。因此导叶翼型的形状和安放位置对水轮机转轮内部流场有着重要的影响。 本文针对某混流式水轮机在高于额定水头产生叶道涡并引起水力振动的情况,根据流体力学理论,分析水轮机产生叶道涡的原因。通过改变导叶的出流角和活动导叶形状,从而改变水轮机内部流场,以达到满足转轮进口水流的要求。运用ANSYS CFX软件,对研究的工况进行流场的数值模拟,与电站的实测数据进行对比,提出解决方案,达到减少振动的目的。
[Abstract]:When the Francis turbine deviates from the optimal operation condition and is higher than the rated water head, the water flow is partially separated from the inlet of the runner blade near the upper crown, resulting in the passage vortex, which flows out from the blades and affects the internal flow field of the turbine. When the blade vortex develops to a certain extent, it will cause the hydraulic vibration of the turbine. When the vibration exceeds the allowable value, especially if it is in a long-term state of vibration, and even resonates with the parts and components of the turbine, It will seriously threaten the stable and safe operation of electrical and mechanical equipment of hydropower station and the personal safety of staff. The guiding mechanism is an important overflow component of Francis turbine. The flow of water flows out of the volute and the fixed guide vane, and the flow pattern changes through the guide vane, which affects the size and direction of the flow velocity at the inlet of the runner. Therefore, the shape and placement position of the guide blade have an important influence on the internal flow field of the turbine runner. In this paper, according to the hydrodynamics theory, the cause of turbine vane vortex is analyzed according to the case that a Francis turbine produces blade vortex above the rated head and results in hydraulic vibration. By changing the outlet angle and the shape of the moving guide vane, the internal flow field of the turbine can be changed to meet the requirements of the inlet flow of the runner. By using ANSYS CFX software, the numerical simulation of the flow field under the studied condition is carried out, compared with the measured data of the power station, and the solution is put forward to reduce the vibration.
【学位授予单位】：西华大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TK733.1
本文编号：2457089
[Abstract]:When the Francis turbine deviates from the optimal operation condition and is higher than the rated water head, the water flow is partially separated from the inlet of the runner blade near the upper crown, resulting in the passage vortex, which flows out from the blades and affects the internal flow field of the turbine. When the blade vortex develops to a certain extent, it will cause the hydraulic vibration of the turbine. When the vibration exceeds the allowable value, especially if it is in a long-term state of vibration, and even resonates with the parts and components of the turbine, It will seriously threaten the stable and safe operation of electrical and mechanical equipment of hydropower station and the personal safety of staff. The guiding mechanism is an important overflow component of Francis turbine. The flow of water flows out of the volute and the fixed guide vane, and the flow pattern changes through the guide vane, which affects the size and direction of the flow velocity at the inlet of the runner. Therefore, the shape and placement position of the guide blade have an important influence on the internal flow field of the turbine runner. In this paper, according to the hydrodynamics theory, the cause of turbine vane vortex is analyzed according to the case that a Francis turbine produces blade vortex above the rated head and results in hydraulic vibration. By changing the outlet angle and the shape of the moving guide vane, the internal flow field of the turbine can be changed to meet the requirements of the inlet flow of the runner. By using ANSYS CFX software, the numerical simulation of the flow field under the studied condition is carried out, compared with the measured data of the power station, and the solution is put forward to reduce the vibration.
【学位授予单位】：西华大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TK733.1
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