The effect of flowing water on turbine rotor vibrations

• Main Author: Jansson, Ida
• Format: Master Thesis
• Language: English
• Published: Luleå tekniska universitet, Strömningslära och experimentell mekanik 2010
• Subjects: Fluid Mechanics and Acoustics; Strömningsmekanik och akustik; Luleå
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17485

There is a lack of standardized rules on how the fluid in the turbine should be included in rotor models of hydraulic machinery. This thesis is an attempt to shed some light on this issue. We approach the problem from two viewpoints, situated at place at a hydropower plant and by mathematical analysis.One goal of the thesis is to develop a measurement system that monitors the instantaneous pressure at several locations of a runner blade on a 10 MW Kaplan prototype in Porjus along Lule river. Paper A outlines the development of the measurement system and the instrumentation of the runner blade. Miniature piezo-resisitive pressure transducers were mounted flush to the surface. If instrumentation is successful, the pressure field of the runner blade could be measured simultaneously as the loads and displacements of the guide bearings and the generator.The second objective is concerned with how the motion-induced fluid force affects the dynamic behaviour of the rotor. Inertia and angular momentum of the fluid and shrouding are expected to influence the dynamic behaviour of the turbine. Paper B scrutinizes this assumption by presenting a simple fluid-rotor model that captures the effects of inertia and angular momentum of the fluid on the motion of a confined cylinder. The simplicity of the model allows for powerful analytical solution methods. The results show that fluid inertia, angular momentum and shrouding of hydraulic turbines could have substantial effects on lateral rotor vibrations. This calls for further investigation with a more complex fluid-rotor model that accounts for flexural bending modes. Godkänd; 2010; 20100915 (idajoh); LICENTIATSEMINARIUM Ämnesområde: Strömningslära/Fluid Mechanics Examinator: Professor Staffan Lundström, Luleå tekniska universitet Diskutant: Filosofie doktor Jörgen Burman, ITT Water & Wastewater Sverige, Sundbyberg Tid: Fredag den 15 oktober 2010 kl 10.00 Plats: E243, Luleå tekniska universitet