Huge Water Turbine Vibration Analysis And The Viscous Fluid-Elastic Structure Interaction Finite Element Scheme

Three Gorges Hydroelectric Station is one of gigantic projects in the world with enormous economical and social benefits. The hydraulic generator units will be among the largest in the world. As the size of the hydraulic generator units increases, the operation stability becomes the very important consideration in the design process. Two aspects will affect the operation stability: the draft tube surges, and the flow induced vibration of turbine blade. The later aspect is one kind of fluid-structure interaction. In engineering, there are many similar problems such as the vibration of suspend bridges in the wind. These, together with the stability consideration of hydraulic generator units, are the engineering background of this thesis.The draft tube surges influence the operation stability by exerting periodical unbalanced transverse forces on the ainner. Very few work has been carried out in this area because of the complexity of the flow inside the huge turbine. There are many methods for solving fluid-structure interaction problems. Most of these methods take the fluid as non-viscid media with limited fluid displacement. As a result, these methods are lack of the ability to analyze the complex fluid-structure interaction problems, in which viscosity of fluid plays an important role.As to the flow-induced vibration of turbine blade and other fluid-structure interaction problems in engineering, a general numerical procedure is developed. The fluid is considered to be incompressible viscous media and many related complex phenomena are taken inconsideration. The detailed works in this part can be summarized as follows: 1). Based on the investigation of the engineering problems, the fluid is considered to be imcompressible viscous. SU/PG finite element is employed to analysis the fluid flow. The theory is proved here, and the upwind parameter is obtained through deduction. 2). A simplified SU/PG finite element method is employed to analyze the flow and based on this method a program is completed. Two numerical examples are given. The results of steady and unsteady problems are quite accurate. 3). Arbitrary Lagrangian-Eulerian description is used to incorporate the interface condition between the structure and the fluid. Based on the essence of ALE, some regulations of mesh regeneration are put forward. 4). The interaction modal of incompressible viscous fluid and structure is given. 5). A modified Predictor-Multicorrector solving procedure is proposed to solve the nonlinear equations of the coupled system. 6). A program is completed. Three numerical examples are computed. The influences of different parameters of fluid are analyzed. The fluid-induced vibration of a plate is obtained.As the auxiliary works, some efforts are made to visualize the computational results. The color contour of pressure, and the vector distribution of fluid can be directly perceived in graphic sense. A simple method is used to produce simple cartoons, which display the interacting process of fluid and structure in the engineering analysis.