A preliminary investigation of the added properties called added mass, added damping and added stiffness have been performed for a Kaplan turbine. The magnitude of dimensionless numbers have been used in order to classify the interaction of the fluid and the solid. The classification is done to bring clarity in which of the added properties are of importance for the system. The diameter of the runner and the hub have been calculated using the power output and the head for a Kaplan turbine. These dimensions have been used to determine the magnitude of the dimensionless numbers along with the velocity of the fluid. It turned out that all added properties affect the turbine, however, the magnitude of them are quite different. The magnitude of the added mass and the added damping are greater than the added stiffness, which often is neglected. The added mass can be determined if the natural frequencies of the structure in air and in water are known. The difference in natural frequencies can be used to determine the added mass factor and thereby the added mass of the system. The added damping can be determined by the change in damping ratio for different surrounding fluids. This was done using the simulation software ANSYS Workbench v.17.1, where two different types of simulation were used, ”acoustic coupled simulation” and ”two way coupled simulation”. The complexity of the geometry of the Kaplan turbine was simplified to a disc and a shaft. The result for the added mass was validated using results from an experiment [1]. The added damping could be determined, but not validated. The different types of simulation have been compared and it turned out that the added mass could be determined using ”acoustic coupled simulation” and ”two way coupled simulation”, but the added damping could only be determined using the ”two way coupled simulation”. / En preliminär undersökning av de adderade egenskaperna kallade, adderad massa, adderad dämpning och adderad styvhet har utförts för en Kaplan turbin. Magnituden av dimensionslösa tal har använts för att klassificera interaktionen av fluiden och soliden. Klassificeringen görs för att bringa klarhet i vilka av de adderade egenskaperna är av betydelse för systemet. Diametrarna för löphjulet och navet har beräknats utifrån effekt och fallhöjd för en Kaplan turbin. Dessa längder har använts för att bestämma magnituden av de dimensionslösa talen tillsammans med fluidens hastighet. Det visade sig att alla adderade egenskaper påverkar turbinen, men omfattningen av dem är helt annorlunda. Magnituden av den adderade massan och den adderade dämpningen är större än den adderade styvheten, som ofta försummas. Den adderade massan kan bestämmas om de naturliga frekvenserna av strukturen i luft och vatten är kända. Skillnaden i egenfrekvenser kan användas för att bestämma faktorn av den adderade massan och därigenom den adderade massan. Den adderade dämpningen kan bestämmas genom ändringen i dämpningsförhållande för olika omgivande fluider. Detta gjordes med hjälp av simuleringsprogrammet ANSYS Workbench v.17.1, där två olika typer av simulering användes, ”acoustic coupled simulation” och ”two way coupled simulation”. Komplexiteten i geometrin för en Kaplan turbin förenklades till en skiva och en axel. Resultatet för den adderade massan validerades med resultat från ett experiment [1]. Den adderade dämpningen kunde bestämmas, men inte valideras. De olika typerna av simulering har jämförts och det visade sig att den adderade massan kan bestämmas med hjälp av både ”acoustic coupled simulation” och ”two way coupled simulation”, men den adderade dämpningen kunde endast bestämmas med hjälp av ”two way coupled simulation”.

Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2016. / Submitted by Fernanda Percia França (fernandafranca@bce.unb.br) on 2016-09-30T18:04:30Z No. of bitstreams: 1 2016_FernandodosSantosOliveira.pdf: 6646040 bytes, checksum: a918278b21da46660beef0d43415e2b7 (MD5) / Approved for entry into archive by Raquel Viana(raquelviana@bce.unb.br) on 2016-12-19T12:36:52Z (GMT) No. of bitstreams: 1 2016_FernandodosSantosOliveira.pdf: 6646040 bytes, checksum: a918278b21da46660beef0d43415e2b7 (MD5) / Made available in DSpace on 2016-12-19T12:36:52Z (GMT). No. of bitstreams: 1 2016_FernandodosSantosOliveira.pdf: 6646040 bytes, checksum: a918278b21da46660beef0d43415e2b7 (MD5) / A construção de edificações cada vez mais altas e esbeltas tem se tornado bastante comum nos grandes centros, desafiando assim os projetistas estruturais a elaborarem projetos cada vez mais eficientes de forma que o arranjo adotado possa utilizar da melhor forma as características dos materiais. O uso de dispositivos que adicionam rigidez e amortecimento às estruturas sujeitas a ações dinâmicas, como cargas de vento e terremotos, tem se tornado cada vez mais comum nas estruturas civis. Um desses dispositivos mecânicos que tem sido amplamente utilizado é o dissipador do tipo Added Damping and Stiffness (ADAS), que se corretamente instalado, pode aumentar significativamente a resistência, rigidez e capacidade de dissipação de energia das estruturas das edificações. Os dispositivos do tipo ADAS são basicamente dissipadores de energia instalados na estrutura com o objetivo de que a dissipação ocorra de forma concentrada nesses elementos, protegendo assim a estrutura principal de maiores danos. Uma vez ocorrida a ação dinâmica que danifique esses elementos, eles podem ser facilmente substituídos sem maiores dificuldades. Esses dissipadores de energia apresentam a vantagem de não precisarem de tecnologia avançada para sua produção e podem ser facilmente instalados na estrutura. Possuem ainda a vantagem de que fatores ambientais tais como temperatura e umidade, pouco ou nada afetam seu desempenho. No presente estudo, como uma alternativa ao ADAS, é realizada a otimização topológica de um dissipador metálico aplicado à redução de vibração em edificações sujeitas a terremotos, considerando através de análise numérica e experimental o formato adequado desse tipo de dispositivo. Em seguida busca-se a obtenção da probabilidade de falha desse sistema estrutural, levando-se em consideração as incertezas inerentes ao projeto, através da análise de confiabilidade. ________________________________________________________________________________________________ ABSTRACT / The construction of increasingly tall and slender buildings has become quite common in large cities, challenging the structural engineers to develop increasingly efficient designs so that the adopted arrangement can make best use of the characteristics of materials. The use of devices that add stiffness and damping to structures subjected to dynamic actions such as wind and earthquake loads, has become increasingly common in civil structures. One of the mechanical devices that have been widely used is the Added Damping and Stiffness (ADAS), which if correctly installed, can significantly increase the strength, stiffness and energy dissipation capacity of the structures. ADAS devices are basically energy dissipators installed in the structure in order that dissipation occurs in these elements in a concentrated way, thereby protecting the main structure from further damage. Once the dynamic action that damages these elements occurs, they can be easily replaced without major costs. These energy dissipators have the further advantage of not require advanced technology for its production and can be easily installed in the structure. They also have the advantage that environmental factors such as temperature and humidity, has little or no effect in their performance. In the present study, as an alternative to ADAS, is performed the topology optimization of a metallic dissipator applied to the reduction of vibration in buildings subject to earthquakes, raising through numerical and experimental analysis the appropriate device type format. Then is searched the probability of failure of this structural system, taking into consideration the uncertainty inherent in the design, through reliability analysis.

The concept of added hydrodynamic properties such as added mass is of importance in modern hydropower development, mainly for rotor dynamic calculations. Added mass could result in reduced natural frequencies and altered mode compared to existing simulation models. It is of importance to quantify added mass but also added damping to make the simulation models more accurate. Experiments are conducted on a model Kaplan turbine, D = 0,5 m, and a steel cube, S = 0,2 m, for linear vibrations in still water confined in a cylindrical tank. The experiments are conducted in air and water for evaluation of added forces. The vibrations are generated with an electrodynamic vibration exciter with a frequency range of approximately 1-10 Hz with amplitudes 0,5-3 mm. The experiments were repeated to check test rig reliability. Each individual working point [frequency, amplitude] were in total tested 40 times in 15 s intervals. The added mass was found to be function of acceleration for the model Kaplan with an increase in added mass from 10 % at 4 m/s2 to 35 % at 0,5 m/s2. The damping forces was at best measured at ±30 %, making added damping calculations unreliable. The cube experiments resulted in small differences between water and air. Cube results must be interpreted with caution due to test rig uncertainties.

An experimental investigation of a vibrating Kaplan turbine runner was performed in order to understand the hydrodynamic effects and to obtain or confirm the mass and damping coefficients used for dimensioning at the design stage. Improved design can lead to increased efficiency and lifetime of hydropower stations. The method was based on the 90◦ phase shift between acceleration and velocity and their relationship with mass and damping respectively. The experiment examined frequencies between 1–9 Hz at displacements between 0.25–2.00 mm. Results showed a frequency dependent added mass which varied between 1.2 and 1.5 (neglecting the highest and lowest frequencies) and an added damping between 0.8 and 1.2 which became of importance at low frequencies. A mathematical interpretation of the fluid solid interactions (based on the constitutive equation for stresses in a Newtonian fluid) has been derived and connected to the obtained experimental data.

New approach for computational modeling of the dynamic behavior of elastic body immersed in incompressible viscous stagnant fluid is described in this work. It is based on determination of added effects (added mass and added damping). This effects are inserted into computational model and it replace influence of the fluid. Commonly used commercial computational software may be used. Approach is based on assumption appropriate for the linear flow. Two pressure field are determined. One for movement of the unite acceleration of the fluid boundary and the second for unite velocity. Nonlinear model (Navier-Stokes equation in ALE form) had to be used for determination of the added damping, hence results are valid only for pre-selected amplitude of vibration.