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Luo Y.,Tsinghua University | Wang Z.,Tsinghua University | Zeng J.,Fujian Shuikou Hydropower Station | Lin J.,Fujian Shuikou Hydropower Station
Engineering Failure Analysis | Year: 2010

The stresses in Kaplan turbine piston rod were analyzed to predict failure conditions based on the 3D unsteady flow through the Kaplan turbine. The results show that the predicted stress concentration position in the rod agrees well with the actual fracture position. The mean stress and the dynamic stress in the rod varied greatly with operating conditions. The dynamic stress reached 46.0 MPa at the high head low output condition, which caused the final rod failure. The mean of the dynamic stresses in the rod increase with increasing blade angle error, but the amplitudes decrease. © 2009 Elsevier Ltd. All rights reserved.

Luo Y.,Tsinghua University | Wang Z.,Tsinghua University | Zhang J.,Tsinghua University | Zeng J.,Fujian Shuikou Hydropower Station | And 2 more authors.
Engineering Computations (Swansea, Wales) | Year: 2013

Purpose - Hydraulic instabilities are one of the most important reasons causing vibrations and fatigues in hydraulic turbines. The present paper aims to find the relationship between pressure pulsations and fatigues of key parts of a Kaplan turbine. Design/methodology/approach - 3D unsteady numerical simulations were preformed for a number of operating conditions at high heads for a prototype Kaplan turbine, with the numerical results verified by online monitoring data. The contact method and the weak fluid-structure interaction method were used to calculate the stresses in the multi-body mechanism of the Kaplan turbine runner body based on the unsteady flow simulation result. Findings - The results show that vortices in the vaneless space between the guide vanes and blades cause large pressure pulsations and vibrations for high heads with small guide vane openings. The dynamic stresses in the runner body parts are small for high heads with large guide vane openings, but are large for high heads with small guide vane openings. Originality/value - A comprehensive numerical method including computational fluid dynamics analyses, finite element analyses and the contact method for multi-body dynamics has been used to identity the sources of unit vibrations and key part failures. © Emerald Group Publishing Limited.

Wang Z.,Tsinghua University | Qin L.,Tianjin Dredging Co. | Zeng J.,Fujian Shuikou Hydropower Station | Lin J.,Fujian Shuikou Hydropower Station | And 4 more authors.
Science China Technological Sciences | Year: 2010

The operating states of hydroelectric generating units vary widely as the operating condition change. The details of the operating characteristics and the operating region partitioning method are discussed for two types of large Francis turbines in the Wanjiazhai Hydropower Plant and two same type large Kaplan turbines in the Shuikou Hydropower Plant. For the Wanjiazhai Hydropower units, the most critical factor affecting the operating stability is the hydraulic pressure fluctuations caused by the vortex rope in the draft tube. For Shuikou Hydropower units, the dynamic stresses as in the piston rod and the blade and the hydraulic thrust on the runner induced by the pressure fluctuations in the flow passage should be used to partition the operating regions. Analyzing the distribution cloud of operating characteristic factors which affects the operating stability in the hill-chart for each individual unit, the forbidden, stable and transient operating regions can be obtained. © 2010 Science in China Press and Springer Berlin Heidelberg.

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