Influence of the thrust bearing on the natural frequencies of a 72-MW hydropower rotor

[摘要] The thrust bearing is an essential element of a hydropower machine. Not only does it carry the total axial load but it also introduces stiffness and damping properties in the system. The focus of this study is on the influence of the thrust bearing on the lateral vibrations of the shaft of a 72-MW propeller turbine. The thrust bearing has a non-conventional design with a large radius and two rows of thrust pads. A numerical model is developed to estimate natural frequencies. Numerical results are analyzed and related to experimental measurements of a runaway test. The results show the need to include the thrust bearing in the model. In fact, the vibration modes are substantially increased towards higher frequencies with the added properties from the thrust bearing. The second mode of vibration has been identified in the experimental measurements. Its frequency and mode shape compare well with numerical results.

[发布机构] Hydro-Québec Research Institute, Varennes; QC; J3X 1S1, Canada^1;Division of Product and Production Development, Luleå University of Technology, Luleå; 97187, Sweden^2

[关键词] Conventional design;Essential elements;Higher frequencies;Lateral vibrations;Numerical results;Propeller turbines;Stiffness and damping;Vibration modes