Zugl.: Siegen, Univ., Diss., 2009

Wuppertal, Universiẗat, Thesis (doctoral).

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-12-12T18:05:10Z No. of bitstreams: 1 AdjairFerreiraBarrosFilho_TESE.pdf: 9926886 bytes, checksum: 1d2dea348ca690f1fa1fc74730374929 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-12-13T19:41:36Z (GMT) No. of bitstreams: 1 AdjairFerreiraBarrosFilho_TESE.pdf: 9926886 bytes, checksum: 1d2dea348ca690f1fa1fc74730374929 (MD5) / Made available in DSpace on 2017-12-13T19:41:36Z (GMT). No. of bitstreams: 1 AdjairFerreiraBarrosFilho_TESE.pdf: 9926886 bytes, checksum: 1d2dea348ca690f1fa1fc74730374929 (MD5) Previous issue date: 2017-10-09 / Esta tese tem como objetivo o estudo e a constru??o de um prot?tipo de motor de indu??o trif?sico de pequenas dimens?es (28,6 mm de di?metro externo e 15 mm de altura), com o rotor externo do tipo gaiola de esquilo sendo utilizado como motor-mancal. Esse estudo iniciou utilizando um motor Brushless convencional e que foi adaptado para funcionar como motor de indu??o com rotor externo. O motor de indu??o sem mancais utiliza a configura??o de bobinado dividido para conseguir o posicionamento radial. Foram realizados estudos de simula??es utilizando o M?todo dos Elementos Finitos ? FEM mostrando efetivamente que ? poss?vel controlar a posi??o radial para manter o rotor girando. Foi constru?do e testado um primeiro prot?tipo com sucesso, para uma pot?ncia de 100 W mostrando um bom potencial para aplica??es nesta faixa de pot?ncia e tamanho, como os aplicados em sistemas de cora??o artificial. O sistema de controle foi implementado utilizando o Processador Digital de Sinais ? DSP TMS 320F28335. / This thesis aims the study and construction of a prototype of a small three-phase induction motor (28.6 mm outside diameter and 15 mm height), with the external squirrel cage-type rotor being used as a Bearingless motor. This study started using a conventional Brushless motor and was adapted to function as an external rotor induction motor. The bearingless induction motor uses the split winding configuration to achieve radial positioning. Simulation studies were performed by using the Finite Element Method (FEM), effectively showing that it is possible to control the radial position to keep the rotor spinning. A first prototype was successfully built and tested for a power of 100 W showing good potential for applications in this power range and size, such as those applied in artificial heart systems. The control system was implemented using the Digital Signal Processor - DSP TMS 320F28335.

Vibration-based fault diagnosis (FD) with a simple spectrum can be complex, especially when considering FD of rotating machinery with multiple bearings like a multi-stage turbine. Various studies have sought to better interpret fault spectra, but the process remains equivocal. Consequently, it has been accepted that the simple spectra requires support from additional techniques, such as orbit analysis. But even orbit analysis can be inconclusive. Though promising, attempts at developing viable methods that rival the failure coverage of spectrum analysis without gaining computational complexity remain protracted. Interestingly, few researchers have developed FD methods for transient machine operation, however, these have proven to be involved. Current practices limit vibration data to a single machine, which usually requires a large unique data history. However, if sharing of data between similar machines with different foundations was possible, the need for unique histories would be mitigated. From readily available works, this has not been encountered. Therefore, a simple but robust vibration-based approach is warranted. In light of this, a novel on-bearing vibration response integration approach for condition monitoring of shaft-related faults irrespective of speed and foundation type is proposed in the present study. Vibration data are acquired at different speeds for: a baseline, unbalance, bow, crack, looseness, misalignment, and rub conditions on three laboratory rigs with dynamically different foundations, namely: rigid, flexible support 1 (FS1) and flexible support 2 (FS2). Testing is done on the rigid rig set up first, then FS1, and afterwards FS2. Common vibration features are computed from the measured data to be input to the proposed approach for further processing. First, the proposed approach is developed through its application to a machine at a steady speed in a novel Single-speed FD technique which exploits a single vibration sensor per bearing and fusion of features from different bearings for FD. Initially, vibration features are supplemented with bearing temperature readings with improved classification compared to vibration features alone. However, it is observed that temperature readings are insensitive to faults on the FS1 and FS2 rigs, when compared to vibration features, which are standardised for consistent classification on the different rigs tested. Thus, temperature is not included as a final feature. The observed fault classifications on the different rigs at different speeds with the standardised vibration features are encouraging. Thereafter, a novel Unified Multi-speed FD technique that is based on the initial proposed approach and which works by fusion of vibration features from different bearings at different speeds in a single analysis step for FD is proposed. Experiments on the different rigs repeatedly show the novel Multi-speed technique to be suitable for transient machine operation. Then, a novel generic Multi-foundation Technique (also based on the proposed approach) that allows sharing of vibration data of a wide range of fault conditions between two similarly configured machines with similar speed operation but different foundations is implemented to further mitigate data requirements in the FD process. Observations made with the rigs during steady and transient speed tests show this technique is applicable in situations where data history is available on one machine but lacking on the other. Comparison of experimental results with results obtained from theoretical simulations indicates the approach is consistent. Thus, the proposed approach has the potential for practical considerations.

The Large Eddy Simulation approach is employed to predict the flow physics and heat transfer characteristics of a film-cooling problem that is formed from the interaction of a coolant jet with a hot mainstream flow. The film-cooling technique is used to protect turbine blades from thermal failure, allowing the gas inlet temperature to be increased beyond the failure temperature of the turbine blade material in order to enhance the efficiency of gas turbine engines. A coolant fluid is injected into the hot mainstream through several rows of injection holes placed on the surface of a gas turbine blade in order to form a protective coolant film layer on the blade surface. However, due to the complex, unsteady and three-dimensional interactions between the coolant and the hot gases, it is difficult to achieve the desired cooling performance. Understanding of this complex flow and heat transfer process will be helpful in designing more efficiently cooled rotor blades. A comprehensive numerical investigation of a rotating film-cooling performance under different conditions is conducted in this thesis, including film-cooling on a flat surface and film-cooling on a rotating gas turbine blade. The flow-governing equations are discretised based on the finite-volumes method and then solved iteratively using the well-known SIMPLE and PISO algorithms. An in-house FORTRAN code has been developed to investigate the flat plate film-cooling configuration, while the gas turbine blade geometry has been simulated using the STAR-CCM+ CFD commercial code. The first goal of the present thesis is to investigate the physics of the flow and heat transfer, which occurs during film-cooling from a standard film hole configuration. Film-cooling performance is analysed by looking at the distribution of flow and thermal fields downstream of the film holes. The predicted mean velocity profiles and spanwise-averaged film-cooling effectiveness are compared with experimental data in order to validate the reliability of the LES technique. Comparison of adiabatic film-cooling effectiveness with experiments shows excellent agreement for the local and spanwise-averaged film-cooling effectiveness, confirming the correct prediction of the film-cooling behaviour. The film coverage and film-cooling effectiveness distributions are presented along with discussions of the influence of blowing ratio and rotation number. Overall, it was found that both rotation number and blowing ratio play significant roles in determining the film-cooling effectiveness distributions. The second goal is to investigate the impact of innovative anti-vortex holes on the film-cooling performance. The anti-vortex hole design counteracts the detrimental kidney vorticity associated with the main hole, allowing coolant to remain attached to the blade surface. Thus, the new design significantly improves the film-cooling performance compared to the standard hole arrangement, particularly at high blowing ratios. The anti-vortex hole technique is unique in that it requires only readily machinable round holes, unlike shaped film-cooling holes and other advanced concepts. The effects of blowing ratio and the positions of the anti-vortex side holes on the physics of the hot mainstream-coolant interaction in a film-cooled turbine blade are also investigated. The results also indicate that the side holes of the anti-vortex design promote the interaction between the vortical structures; therefore, the film coverage contours reveal an improvement in the lateral spreading of the coolant jet.

Made available in DSpace on 2014-06-11T19:27:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-09-30Bitstream added on 2014-06-13T18:31:09Z : No. of bitstreams: 1 caldiron_l_me_ilha_prot.pdf: 995296 bytes, checksum: dc02ada2316a49ff3c8fd3dca71338ba (MD5) / Neste trabalho são otimizadas rotinas computacionais de um método de estimação de rigidez de mancais de máquinas através de um processo de ajuste de modelo, utilizando a análise de sensibilidade. Este método consiste em utilizar a análise de sensibilidade dos autovalores com relação à variação da rigidez dos mancais de um rotor. A eficácia e a robustez do método são analisadas através de simulações teóricas, bem como através de dados experimentais obtidos de um rotor de rotação variável e rigidezes dos mancais ajustáveis. O modelo matemático de ajuste do sistema é desenvolvido pelo método dos elementos finitos e o método de ajuste converge empregando-se um processo iterativo. Este método de ajuste baseia-se na minimização da diferença entre autovalores experimentais e autovalores obtidos com o modelo matemático de ajuste a partir de valores de rigidez dos mancais previamente adotados. A análise é feita com o rotor em diversas velocidades de rotação para verificar a influência do efeito giroscópio, e em diversas condições de valores da rigidez dos mancais para analisar o método quando aplicado em rotores flexíveis e em rotores rígidos. O desempenho do método é analisado com resultados teóricos e experimentais. / In this work, computational routines of estimation method of stiffness bearing of machine via a model updating process are optimized, using the sensitivity analysis. This method consists of using the eigenvalue sensitivity analysis, relating to the stiffness bearing variation of a rotor. The efficacy and the robustness of the method are analyzed through the theoretical simulations, as well as, based on the experimental data obtained of a test rotor with variable rotating speeds and adjustable bearing stiffness values. The mathematical model system is developed by the finite element method and the method of adjustment should converge employing an iterative process. The method of adjustment is based on the minimization of the difference between experimental eigenvalues and eigenvalues obtained via mathematical model from previously adopted stiffness bearing values. The analysis is made by using the rotor in different rotating speeds in order to check the influence of the gyroscopic effect, and in several conditions of the stiffness bearing values to analyze the method when applied on flexible and rigid rotors. The performance of the method is analyzed through theoretical and experimental results.

Submitted by maria angelica Varella (angelica@sibi.ufrj.br) on 2018-01-31T13:18:36Z No. of bitstreams: 1 146266.pdf: 1696911 bytes, checksum: 00a8e33aea3bf9b1692147c7d267546e (MD5) / Made available in DSpace on 2018-01-31T13:18:37Z (GMT). No. of bitstreams: 1 146266.pdf: 1696911 bytes, checksum: 00a8e33aea3bf9b1692147c7d267546e (MD5) Previous issue date: 1977-09 / Desenvolveu-se um modelo de rotor que pudesse funcionar a altas rotações e com algumas particularidades visando um posterior estudo de dinâmica de gases. Obteve-se corro estrutura do modelo um conjunto formado por duas bases circulares (onde se localizam os mancais) separadas por três colunas, sendo o conjunto fixado a uma bancada. O rotor compõem-se de três peças: duas tampas-eixo encaixadas nas extremidades de um cilindro oco feito de acrílico translúcido. Construído e montado o modelo realizou-se o balanceamento dinâmico do rotor medindo-se a vibração na altura de cada tampa-eixo. Colocando-se o rotor a girar a uma determinada velocidade em três situações diferentes (com o rotor ''no estado com o acréscimo de um peso conhecido em uma das tampas – eixo e com acréscimo do mesmo peso na outra tampa-eixo)fica-se conhecendo posição e magnitude das maiores vibrações nesses três testes, podendo-se, a partir daí balancear o sistema. Utilizou-se para a medição da vibração: a) sensores especialmente desenvolvidos, capazes de detetar deslocamentos radiais do rotor, da ordem de micra; b) equipamento para registrar os sinais provenientes dos sensores. Primeiramente utilizou-se para registro um gravador e um oscilógrafo. Esse equipamento mostrou-se inadequado devido a introdução, pelo gravador de ruídos estranhos e devido a densificação de dados pelo oscilógrafo. Utilizou-se então para registro uma máquina fotográfica POLAROID acoplada a um osciloscópio. A caracterização da vibração foi feita graficamente a partir de ampliações das fotos feitas durante o teste. Concluiu-se que na tampa-eixo próxima da bancada não se detetava vibração e que na altura da outra tampa o nível de vibração era considerável. Balanceou-se o rotor na região onde a vibração se manifestava empregando-se o método do disco. Os resultados satisfatórios mostram a viabilidade do método desenvolvido. / It was developed a high speed rotor modelas a basis for a further study on dynamic of gases. We have obtained a model structure consisting of two round bases (where are fixed the bearings), spaced by three small columns. This assembly has one of its ends fixed to a bench. The rotor consists of three parts: two shaft-plates fitted each one at the ends of a hollow cilinder made with acrilic. Since we have this model carefully machined and assembled we have proceed toward the dynamic balance of the system. That was obtained through the vibration measurement at each one of the shaft-plates in three different arrangements: 1. the rotor as built up. 2. the rotor with a known weight in one of the shaft-plates. 3. the rotor with the sarne known weight at the other shaft- plate. So we have known the position and magnitude of its largest vibration and then we are able to balance the system. For the above mentioned measurements we have used a sensor specialls developed for measuring radial displacemenxs, in arder of micra, and also equipments for recording the vibrations detected by those sensors. At first have been used for recording a tape-recorder and an oscilograph. However these equipment was not adequate dueto the noise added to the sensors input signal by the tape-recorder. Also there have been demonstrated that the oscilograph could not respond quickly enough to the frequency generated by the sensors. Therefore it was used an osciloscopy anda Polaroid camera in order to register graphically the vibration amplitudes. We have concluded that in the shaft-plate close to the bench there was no vibration at all, however in the upper plate the vibration was considerable. Then the rotor was dinamically balanced using the ''discmethod". The results were well satisfactory, proving in that way the viability of the method.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-01-12T14:19:58Z No. of bitstreams: 1 AntonioRobertoAugusto_DISSERT.pdf: 15947966 bytes, checksum: 6137cc9dd87967a91d0ea2a7fd5913a0 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-01-17T13:19:05Z (GMT) No. of bitstreams: 1 AntonioRobertoAugusto_DISSERT.pdf: 15947966 bytes, checksum: 6137cc9dd87967a91d0ea2a7fd5913a0 (MD5) / Made available in DSpace on 2017-01-17T13:19:05Z (GMT). No. of bitstreams: 1 AntonioRobertoAugusto_DISSERT.pdf: 15947966 bytes, checksum: 6137cc9dd87967a91d0ea2a7fd5913a0 (MD5) Previous issue date: 2014-09-01 / A lideran?a mundial brasileira na obten??o de etanol derivado da cana de a??car pode ser associada ? produ??o do vinhoto, em uma raz?o de 10 a 18 litros de vinhoto para cada litro de etanol produzido durante o processo de destila??o. Nos cultivos da cana-de-a??car, esse vinhoto tem sido aplicado como adubo org?nico, onde o seu bombeamento ? um elemento cr?tico dessa cadeia produtiva. O objetivo deste trabalho foi investigar os principais mecanismos de desgaste de um rotor e de partes de uma bomba centr?fuga ap?s bombear vinhoto tratado em reator (pH 7,3?0.5). Um filme de 300?75 ?m de metal duro ? base de carboneto de tungst?nio-cobalto (WC-Co) foi aplicado ao rotor de ferro fundido cinzento da bomba atrav?s da t?cnica de aspers?o t?rmica HVOF. Considerando-se os trinta anos de experi?ncia do autor no projeto de sistemas de bombeamento, uma bancada para o bombeamento de vinhoto a 27?2oC foi desenvolvida em Laborat?rio para um servi?o de 1.000 horas atrav?s de ensaios durante dez horas di?rias e cont?nuas de uma bomba modelo INI 32-125 operando sob condi??es de cavita??o, conforme o c?lculo de NPSH. Um sistema de recircula??o do vinhoto foi adotado e controlado por uma v?lvula de descarga empregada comumente em processos industriais. Ap?s os ensaios, tanto o rotor revestido pelo metal duro como algumas partes n?o revestidas da bomba apresentaram um desgaste severo por cavita??o-eros?o, enquanto partes do rotor onde os efeitos da cavita??o s?o menores, o revestimento apresentou um desgaste moderado. / The Brazilian capability concerning to the world's leading producer of sugarcane ethanol can be joined together the vinasse production, which inherent amount discharged by distilling is from 10 to18 liters of vinasse per liter of ethanol produced. This vinasse has been applied in sugar-cane crops as organic fertilizer, where its pumping process is a critical element in this string. The aim of this work was investigate the main wear mechanisms of an impeller and parts of a centrifugal pump after pumping vinasse treated in reactor (pH 8,3?0,7). A tungsten carbide-cobalt (WC10Co4%Cr) film based hard metal of 360?35?m ?m was applied on the grey cast iron pump impeller by HVOF thermal aspersion. Based on the 30 years of experience of the author in the design and mounting of pumping systems, a test rig was developed in Laboratory for 1,000 hours of pumping tests of vinasse at 27?2oC for a continuous service during 10 hours by day for a pump model 32-125, working under cavitation conditions through the calculation of Net Positive Suction Head (NPSH), A recirculating system of the vinasse was adopted and controlled by a discharge valve usually employed in the industrial processes. After the tests, both the coated rotor as the uncoated parts of the pump showed severe wear by cavitation-erosion, while parts of the rotor where the effects of cavitation are smaller, the coating showed a moderate wear.

Orientador: Katia Lucchesi Cavalca Dedini / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-09T21:40:12Z (GMT). No. of bitstreams: 1 Ramalho_DeniseAlves_M.pdf: 10823264 bytes, checksum: 8b25eba0e7c26b9c543a70020d208299 (MD5) Previous issue date: 2006 / Resumo: O objetivo deste trabalho é estender e melhorar a análise dinâmica de um sistema rotorfundação-solo através da inclusão de modelos distintos de perfis de solo. Obtém-se a resposta desbalanceada de um rotor Laval (Jeffcott) simples bidimensional com mancais rígidos. O rotor é colocado sobre uma fundação de bloco rígido. Os perfis de solo incluem o modelo clássico de semi-espaço e o modelo de solo sobre base rígida. Em particular, uma camada sobre base rígida com diferentes valores de profundidade será considerada. A resposta dinâmica do solo é obtida no domínio da freqüência. O mecanismo de amortecimento interno do solo é considerado. Vários estudos paramétricos são realizados para avaliar o papel da espessura da camada do solo, do coeficiente de amortecimento do solo, da inércia da fundação e da altura dos mancais na resposta ao desbalancemento do rotor. Acredita-se que a análise deste modelo simples de rotor-fundação-solo ajudará a esclarecer o papel dos parâmetros mencionados na resposta dinâmica do rotor / Abstract: The aim of the present work is to extend and improve the dynamic analysis of a rotorfoundation-soil system by including the modelling of distinct soil profiles. The unbalance response of a simple two-dimensional Laval (Jeffcott) rotor with rigid bearings is performed. The rotor is attached to a rigid strip foundation (block foundation). The soil profiles, on the other hand, include the classical half-space but also stratified soils. In particular, a layer with various depths over a bedrock will be considered. The soil¿s dynamic response is furnished in terms of frequency dependent complex impedances. The soil internal damping mechanism is also addressed by making the soil a viscoelastic continuum. A series of parametric studies are perfomed to assess the role of soil layer thickness, soil internal damping coefficient, foundation inertia and bearing height on the rotor unbalance response. It is believed that the analysis of this simple otor-foundation-soil model will help to clarify the role of the mentioned parameters on the rotor dynamic response / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Orientador: Milton Dias Junior / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-10T08:27:27Z (GMT). No. of bitstreams: 1 Idehara_SergioJunichi_D.pdf: 6234443 bytes, checksum: 5071d7a2383df6369dbeaf00f65fb511 (MD5) Previous issue date: 2007 / Resumo: Este trabalho consiste na investigação de algoritmos da filtragem adaptativa utilizados no contexto da identificação de parâmetros. Apesar de ainda ser uma técnica pouco explorada na engenharia mecânica, os algoritmos adaptativos, com destaque para o método dos mínimos quadrados recursivo e mínimos quadrados com decomposição QR, podem ser implementados na prática com base na equação diferencial de segunda ordem para a caracterização dos parâmetros modais. A partir dessa colocação, esse estudo tem como objetivo compreender como se dá a dinâmica de estruturas e máquinas rotativas. Muitas vezes, ao se executar uma análise em campo, depara-se com a situação em que as máquinas da planta não podem ter seu funcionamento interrompido. Dessa forma, ao realizar medições nestes equipamentos ou nas estruturas ao redor, adquirem-se também componentes de vibrações desconhecidas provenientes da operação destas máquinas. Nesse sentido, a metodologia desenvolvida apresenta contribuição em duas áreas distintas. Primeiramente, ela permite realizar a análise modal experimental de estruturas mesmo com a presença de excitação harmônica desconhecida nas medições, necessitando, para isto, apenas conhecer a freqüência instantânea da harmônica. Na visão da dinâmica de rotores, por outro lado, a metodologia possibilita a identificação dos parâmetros modais do sistema com este operando em uma condição não-estacionária, por exemplo, durante a partida ou parada da máquina, bastando que se conheça a rotação da mesma. Os resultados apontam para uma boa precisão da estimativa das freqüências naturais e dos modos de vibrar, mesmo quando há variação temporal dos parâmetros modais. As análises numéricas e experimentais revelam uma maior dificuldade de identificar o fator de amortecimento, principalmente quando o sinal é malcondicionado. Dentre as várias características destes métodos destaca-se a possibilidade de determinar os parâmetros modais em tempo-real / Abstract: This work investigates the use of adaptive filters for parameter identification. Although adaptive algorithms are still rarely utilized in the mechanical engineering field, the recursive least square and recursive least square with QR decomposition methods can be implemented based on the second ordinary differential equations in order to characterize the modal parameters. With this in mind, this study seeks to understand structure and rotating machine dynamics. In many case, when performing field analysis, it is common to face the situation where it is impossible to stop some critical equipments. In this case, all measurements performed on these equipments and the neighboring structures will be corrupted by the harmonic noise generated during the operation of these machines. In this direction, the proposed methodology contributes to the solution of this problem in two distinct ways. First, this approach can handle with measurements coming from experimental modal analysis of structures even when they are corrupted by harmonic noise. The only information needed is the instantaneous frequency of this noise. For rotor dynamics, on the other hand, the methodology allows the identification of the modal parameters of the system while this is operating in non-stationary condition, for example, during start-up or shut-down. In this case the measurement of the rotational speed is also required. The results suggest that the natural frequency and the vibration modes are precisely estimated, even for time varying systems. The numerical and experimental analysis reveals difficulty on the identification of the damping factor, especially when the signal is poorly conditioned. Amongst the nice characteristics of these methods, maybe one of the most interesting is the possibility to extract modal parameters in realtime / Doutorado / Mecanica dos Sólidos e Projeto Mecanico / Doutor em Engenharia Mecânica