Revista Recursos Hdricos

DOI:10.5894/rh36n1-4
O texto deste artigo foi submetido para reviso e possvel publicao em janeiro de 2015, tendo sido aceite pela Comisso de Editores Cientficos Associados em fevereiro de 2015. Este artigo parte integrante da Revista Recursos Hdricos, Vol. 36, N 1, 37-46, maio de 2015.

Avaliao de modelos de atrito varivel em transientes hidrulicos

Evaluation of unsteady friction models in transient
pipe flow

Fbio Eduardo Franco Rodrigues Ferreira¹, Joo Marcelo Costa Barbosa², Marco Aurlio Holanda de Castro³

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1 - Mestre em Engenharia Civil – Recursos Hdricos pela Universidade Federal do Cear (2011) /// Doutorando em Engenharia Civil-Recursos Hdricos do Departamento de Engenharia Hidrulica e Saneamento Ambiental da Universidade Federal do Cear. ///
Professor do Instituto Federal de Educao, Cincia e Tecnologia do Cear
2 - Mestre em Engenharia Civil – Recursos Hdricos pela Universidade Federal do Cear (2010) /// Doutorando em Engenharia Civil-Recursos Hdricos do Departamento de Engenharia Hidrulica e Saneamento Ambiental da Universidade Federal do Cear
3 - Ph.D. em Engenharia pela Drexel University (1994) /// Professor Titular do Departamento de Engenharia Hidrulica e Saneamento Ambiental da Universidade Federal do Cear /// Membro Associado da Associao Brasileira de Recursos Hdricos (ABRH) desde o ano de 1998

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RESUMO
O objetivo deste trabalho estabelecer um comparativo entre dois modelos de atrito transiente, os modelos de Brunone et al. (1991) e de Vardy et al. (1993), e o modelo elstico, com vistas a identificar a abordagem mais adequada para descrio do transiente hidrulico em cenrios de fechamento de vlvula. Para isso, foi desenvolvida uma rotina computacional para simulao dos modelos. Nesse simulador foram definidos os valores dos parmetros dos modelos de atrito varivel. Para o modelo de Brunone et al. (1991), foram utilizadas as equaes de Karney e Brunone (1999) e de Vardy e Brown (1996), para o seu coeficiente de decaimento. Para o modelo de Vardy et al. (1993) foram utilizados parmetros calibrados pelos autores. Os modelos foram avaliados atravs de dados experimentais extrados dos trabalhos de Pezzinga e Scandura (1995) e de Bergant e Simpson (1994), que conduziram experimentos em sistemas do tipo reservatrio-tubo-vlvula, com transiente gerado por fechamento de vlvula. O modelo de Brunone et al. (1991), com coeficiente de amortecimento dado por Karney e Brunone (1999), descreveu com melhor preciso os efeitos de atenuao da onda de presso.

Palavras-chave: transiente hidrulico; atrito transiente; sistema reservatrio-tubo-vlvula.

ABSTRACT
The purpose of this paper is establish a comparison between two unsteady friction models, the Brunone et al.’s model (1991) and the Vardy et al.’s model (1993), and the elastic model, in order to identify the most appropriate approach for description of hydraulic transient in valve closure scenarios. For this, a computational routine was developed to simulate the models. In this simulator the parameter values of the variable friction models were defined. For the Brunone et al.’s model (1991), were used the equations of Brunone and Karney (1999) and of Vardy and Brown (1996), for their decay coefficient. For the Vardy et al.’s model (1993) calibrated parameters by the authors were used. The models were evaluated by experimental data extracted of the researches of Pezzinga and Scandura (1995) and of Bergant and Simpson (1994), who conducted experiments in the Reservoir-Pipe-Valve systems with transient generated by a valve closure. The Brunone et al.’s model (1991), with a damping coefficient given by Karney and Brunone (1999) describe with better precision the effects of attenuation of the pressure wave.

Keywords: hydraulic transient; unsteady friction; reservoir-pipe–valve system.

 

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