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Liu B.,Changjiang Institute of Survey Planning Design and Research | Liu B.,Wuhan University | Liu J.,Yalong River Hydropower Development Co. | Wu H.,Wuhan University
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2013

A three-dimensional nonlinear simulation was made for analysis of a preloaded filling steel spiral case and its overload computation on the basis of an elastoplastic damage model for concrete and the contact nonlinear theory. The analysis focuses on the behavior of spiral case under water pressure increasing, including stress and reinforcement, damage range of surrounding concrete, displacement of generator pier, and deformation of stay ring. The results show that the spiral case alone almost bears all the internal water pressure and its stress increases very rapidly before the internal water pressure reaches the design preloading value. When internal pressure reaches the design value, the damage range of surrounding concrete and the stress of reinforcement become very small. If the overload coefficient exceeds 1.1, the damage range and damage degree on the surrounding concrete increase rapidly, and the deformations of generator pier and stay ring are significant. The spiral case structure still has a certain margin of safety, however, even when this coefficient reaches 1.5. Three-dimensional nonlinear algorithm can produce a simulation closer to the real case, and it should be adopted in design and study of preloaded filling spiral case structure. © right. Source

Liu B.,Changjiang Institute of Survey Planning Design and Research | Lai J.T.,Yalong River Hydropower Development Co.
Progress in Civil, Architectural and Hydraulic Engineering - Selected Papers of the 4th International Conference on Civil, Architectural and Hydraulic Engineering, ICCAHE 2015 | Year: 2016

A three-dimensional finite element model of the water distribution ring pipe in hydropower station has been carried out, using the finite element program ANSYS and nonlinear contact theory. With different preloading water head (0.7, 0.8 and 0.9 times of minimum hydrostatic pressure), the stress of surrounding concrete of the water distributing ring pipe has been analyzed, which provide reference for the optimal selection of the preloading water head. The result shows that the surrounding concrete will not crack in the three schemes, because the design tensile strength of the surrounding concrete of the water distributing ring pipe is high (3.27 MPa). Considering the stress of surrounding concrete and the requirements of unit’s long-term stable operation comprehensively, the water distribution ring pipe’s preloading water head of this project is suggested to be 4.8 MPa, 80% of the minimum head (598.5 m). © 2016 Taylor & Francis Group, London. Source

Zhang L.,Yalong River Hydropower Development Co. | Zhang Y.N.,North China Electrical Power University
IOP Conference Series: Materials Science and Engineering | Year: 2015

Partial Averaged Navier Stokes (PANS) is a numerical approach developed for studying practical engineering problems (e.g. cavitating flow inside hydroturbines) with a resonance cost and accuracy. One of the advantages of PANS is that it is suitable for any filter width, leading a bridging method from traditional Reynolds Averaged Navier-Stokes (RANS) to direct numerical simulations by choosing appropriate parameters. Comparing with RANS, the PANS model will inherit many physical nature from parent RANS but further resolve more scales of motion in great details, leading to PANS superior to RANS. As an important step for PANS approach, one need to identify appropriate physical filter-width control parameters e.g. ratios of unresolved-to-total kinetic energy and dissipation. In present paper, recent studies of cavitating flow based on PANS approach are introduced with a focus on the influences of filter-width control parameters on the simulation results. © Published under licence by IOP Publishing Ltd. Source

Wang H.,Tianjin University | Zheng H.,Tianjin University | Zhou J.,Yalong River Hydropower Development Co.
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2016

This paper presents a combined method for modal identification of hydropower house structures with closely spaced modes, which can reduce mode intensity and improve the precision of modal separation by combining a reverse attenuation index window with wavelet packet frequency division. After modal separation of a signal, a random decrement technique and spare time domain method are used to identify its modal parameters. We have applied this combined method in a case study of the signals of in-situ vibrations in a large-size hydropower house structure with closely spaced modes, and compared with finite element analysis results. The calculations showed that the identification results were in good agreement with the finite element calculations and the damping ratios identified were in the normal range of reinforced concrete structures. © 2016 All right reserved. Source

Yao Y.Q.,Chengdu University of Information Technology | Wang W.B.,Yalong River Hydropower Development Co.
Applied Mechanics and Materials | Year: 2014

A new method to store the harmonic energy is proposed, by offering harmonic energy to DC load directly by combining the diode's one-way electric conduction theory with the first-harmonic resonance theory. Using the PSCAD/EMTDC software to simulate the project in single phase and three phases. And it turn out that the theory is feasible. © (2014) Trans Tech Publications, Switzerland. Source

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