An experimental study of the flow behavior inside the channels of an 8-blade backswept low specific speed impeller at design and off-design conditions is presented. The measurements took place at both the inlet and the outlet of the impeller channel at the mid height of the channel passage. The particle image velocimetry (PIV) technique was used to measure the velocity components in the inlet and outlet frames of the impeller channel. The flow behavior inside the channel, the mean normalized primary and secondary velocity components at six radial locations inside the channels, and turbulence intensity in terms of the variation in the relative velocity components were investigated at the design condition, 75%, 50%, 40%, 30% and 25% of the design flow rate. The results demonstrated a well behaved flow with no evidence of flow separation at the design condition. The fluid flow inside the impeller channel started experiencing a flow separation, when the flow rate is reduced, which propagated throughout the channel passage and caused the channel to stall with a large recirculation zone at severe off-design flow rates.

An experimental study of the flow behavior inside the channels of an 8-blade backswept low specific speed impeller at design and off-design conditions is presented. The measurements took place at both the inlet and the outlet of the impeller channel at the mid height of the channel passage. The particle image velocimetry (PIV) technique was used to measure the velocity components in the inlet and outlet frames of the impeller channel. The flow behavior inside the channel, the mean normalized primary and secondary velocity components at six radial locations inside the channels, and turbulence intensity in terms of the variation in the relative velocity components were investigated at the design condition, 75%, 50%, 40%, 30% and 25% of the design flow rate. The results demonstrated a well behaved flow with no evidence of flow separation at the design condition. The fluid flow inside the impeller channel started experiencing a flow separation, when the flow rate is reduced, which propagated throughout the channel passage and caused the channel to stall with a large recirculation zone at severe off-design flow rates.

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Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 121-122). Also available via the Internet.

published_or_final_version / Mechanical Engineering / Master / Master of Philosophy

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Thesis (M. Phil.)--University of Hong Kong, 1995. / Includes bibliographical references (leaves 188-196).

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Orientador: Antonio Carlos Bannwart / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica e Instituto de Geociências / Made available in DSpace on 2018-08-27T23:44:09Z (GMT). No. of bitstreams: 1 Fleischfresser_NataliaArgeneLovatePereira_M.pdf: 3225949 bytes, checksum: 3fa7cfd39e0757130d24fa627a6c856c (MD5) Previous issue date: 2015 / Resumo: A performance hidráulica de bombas centrífugas depende de várias entre suas dimensões hidráulicas, mas a maioria delas não é facilmente acessível. Por este motivo, a performance hidráulica da bomba deve sempre ser disponibilizada pelo seu fabricante. No entanto, para proteger sua propriedade intelectual, fabricantes raramente compartilham com o público informações mais detalhadas sobre a hidráulica da bomba. Como consequência, os usuários dos equipamentos e pesquisadores não têm acesso a todas as informações de que podem necessitar. Na literatura há diversos modelos propostos para predizer a performance hidráulica de bombas centrífugas. No entanto, até as melhores simulações por CFD não conseguem predizer a performance das bombas com precisão. Neste trabalho, uma abordagem simples (modelo) disponível na literatura, baseada nos princípios de fluido dinâmica, que prediz a performance hidráulica de bombas com poucas e acessíveis dimensões hidráulicas, é validada com uma grande variedade de dados experimentais. Os dados de oitenta testes de diferentes tipos de bomba, cobrindo uma ampla extensão de velocidades específicas, foram considerados. A partir desta análise, correlações entre os coeficientes da equação do modelo e os principais dados hidráulicos das bombas foram propostas. Em seguida, diversos métodos de predição da altura no shut-off disponíveis na literatura foram analisados para que fosse possível definir o que melhor predissesse a altura no shut-off considerando os dados de teste. Finalmente, para cada tipo de bomba, a melhor combinação entre correlações e método de predição de altura no shut-off foi selecionada para reduzir o erro na predição das curvas de altura completas. Dadas todas as premissas e simplificações, o objetivo deste trabalho é apresentar um método aplicável para diversos tipos de bomba que facilmente prediz a curva de altura com erro razoável / Abstract: The hydraulic performance of centrifugal pumps depends on several hydraulic dimensions of the pump, but most of them are not easily accessible. Therefore, the pump¿s hydraulic performance always has to be informed by the pump manufacturer. Furthermore, in order to protect their intellectual property, manufacturers rarely share more detailed information about the pump hydraulics with the public. As a consequence, pump users and researchers don¿t have access to all the data they possibly need. In literature, there are several proposed models to predict the hydraulic performance of centrifugal pumps. However, even the best CFD simulations can¿t predict the pump performance accurately. In this work, a simple approach (model) available in literature, based on fluid dynamics principles, that predicts a pump¿s hydraulic performance with only a few accessible hydraulic dimensions, is validated with several experimental data. Eighty tests of different types of pumps, with a large range of specific speeds were considered. From this analysis, correlations among the coefficients of the model equation and the main hydraulic data of the pumps were proposed. Afterwards, several shut-off head prediction methods available in literature were analyzed in order to define the one that best predicts the shut-off head of the given tested data. Finally, for each pump type, the best combination of correlations and shut-off head prediction method was selected to reduce the error on the whole head curve prediction. Given all the assumptions and simplifications, the objective of this work is to present a method applicable to several pump types that easily provides a prediction of the whole head curve with reasonable error / Mestrado / Explotação / Mestra em Ciências e Engenharia de Petróleo