Abstract
The working principle of a large hydropower station is to guide the high‐pressure water flow to impact the turbine to rotate and generate electricity. The high‐pressure water flow impacts the turbine blades, which forms complex high‐speed eddy currents in the spiral case and the draft tube and causes complicated vortex‐induced vibration problems. Traditionally used harmonic response methods and dynamic time‐history analysis methods are difficult to reflect this complex fluid‐solid dynamic coupling problem. In this paper, the bidirectional fluid‐structure interaction (FSI) simulation analysis theory for a large hydropower house is studied, and the analysis methods of geometric simulation, mechanical simulation, and vibration energy transmission path simulation are presented. A large‐scale 3D fluid‐hydraulic machinery‐concrete structure coupled model of a hydropower house is established to study the vortex‐induced vibration mechanism and coupled vibration law during transient unit operation. A comparison of the fluid results against the in‐site data shows good agreement. Structural responses of vibration displacement, velocity, and acceleration reveal coupled regularity of hydraulic machinery‐concrete structure‐fluid during blades rotating periods, and it comes to the conclusion that the turbine blade rotation is the main vibration source of the hydropower house. The research results can provide a scientific basis for the design and safe operation of the hydropower house.
Highlights
[17] performed a failure analysis of runner blades based on the results of fluid pressure in CFD simulation and concluded that the most likely cause of failure was that turbine operation at low loads, accelerated by detected cavitation, and high water levels in the upper reservoir and tailwater
In existing papers for studying the vibration of the hydropower house, the fluid model and hydraulic machinery are often omitted, or the machinery is simulated as a onedimensional numerical model. e main purpose of this paper is to perform the research on the bidirectional fluid-structure interaction (FSI) simulation analysis theory applicable to large hydropower houses by combining CFD theory and Computational structural dynamics (CSD) theory and to propose the analytical method of geometric simulation, mechanical simulation, and vibration energy transmission path simulation
Based on the powerful FSI function of the commercial software ADINA, a fluid-hydraulic machinery-concrete structure coupled model for Xiangjiaba hydropower house is established, including the concrete structure of the hydropower house, the mechanical structure of the turbine, the generator, the upper and lower brackets, and the fluid inside the entire flow passage. e techniques of the sliding mesh and the upwind scheme are adopted to carry out the FSI bidirectional iterative calculation, and the high-nonlinear dynamic problems are effectively resolved. e vortex-induced vibration mechanism and coupled vibration regularity during transient operation of the unit are discussed. e main vibration source and the transmission path of the hydropower house vibration are clarified, which provides an important reference for the design and construction of the hydropower house
Summary
Connected by the principal axis. e FSI coupled model and transmission path simulation could reflect the transient transmission process of the structural vibration induced by unit operation and the vibration transmitting in the entire structure of the hydropower house. As the core component of the hydraulic turbine, the runner, motivated by high-speed flowing water, drives the generator rotor through the main shaft and transmits the energy of the vibration source upwards through its coupling with water. Vertical dynamic loads such as runner-axis-rotor coupled gravity and axial water pressure imposed on the runner are transferred to the base pier through thrust bearing and bracket. Appropriate element types and well-designed mesh division are chosen to perform geometric and mechanical simulation, Design parameters of the turbine
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