Fluid-Structure Interaction in a Francis Turbine Runner of Splitter Blades
|School||Kunming University of Science and Technology|
|Course||Hydraulic Structure Engineering|
|Keywords||ADINA fluid-structure interaction modal analysis splitter blade runner|
Recently,some of large-scale mixed-flow hydraulic turbine appears strong vibrationn frequently during the operation at home and abroad,especially the problem of turbine blade cracking at high specific speed is very common to see in most hydropower stations around the world,Therefore, it was suggested that application of large density of the splitter blades runner should be used instead of the past.At present, this splitter blades runner are used for high head francis turbine.In some literature there are also existence referred to this cracking phenomenon in this form of the blade runner.This paper will carry out the splitter blades runner(HL-A351)about its modal analysis and analysis of fluid-structure interaction.This paper overviews the dynamic characteristics of the domestic and foreign mixed-flow hydraulic turbine and give a brief introduction about the advantages and disadvantages of the splitter blades runner.Here are the results carried out in the following:1、With the help of the finite element software ANSYS Workbench Geometry, establish the splitter blades runner and fluid regions geometry model. Input Wood-mode to Geometry by the way of draft.Then the blade initial geometric entity is obtained.With the help of ANSYS Workbench Geometry of Entity operating function, the geometric model(1/15 of the runner of regional fluid runner and 1/24 of guide vane fluid region and a group of splitter blades) is completed.2、In order to improve the quality of finite element mesh.This paper will import the geometry model established in ANSYS Workbench Geometry which included the 1/15 of the runner of regional fluid runner and 1/24 of guide vane fluid region and a group of splitter blades into the ICEM CFD to establish the finite element model.The ICEM CFD is a Professional mesh Software.After a long period of exploration and of numerous attempts, it gets a good quality of pure hexahedral mesh finally.3、In this paper, it carries out the modal analysis of the long runner blades, short blades and the splitter blades in the air and the water medium.Numerical calculation is divided into six groups,frequencies and mode shapes are obtained and compared.Hope to find the law of value in the dynamic analysis of splitter blades runner turbine.Blades of modal analysis is relatively simple in the air.Because of the effect of water medium the modal analysis in the water is relatively more complex.This paper adopted potential flow element (ADINA software provided)to simulate water and obtained better results of the mode of blade stress, frequency and mode of vibration.4、The focus of this paper is analysis of fluid-structure interaction in the splitter blades runner. Generally, it gives a rotation angular velocity to the water in runner to describe the movement during flow field analysis for turbine runner.However,in the analysis of fluid-structure interaction,such kind of rotary machine like hydroturbine will rotate under the action of the waterpwer so it can not directly take an angular velocity to make the runner rotate.According to the kinematics,in one case a runner is driven, the other is active.This paper will use the ADINA finite element analysis software to analyze the rotating movement of the splitter blades runner under the action of the hydraulic fluid for fluid-structure interaction analysis,and make a comparison of the results.Finally,some valuable results are obtained.