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Effect of drop in pipe wall stiffness on water-hammer speed and attenuation / Fadi E. Hachem in Journal of hydraulic research, Vol. 50 N° 2 (Mars/Avril 2012) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 218-227 Titre : Effect of drop in pipe wall stiffness on water-hammer speed and attenuation Type de document : texte imprimé Auteurs : Fadi E. Hachem, Auteur ; Anton J. Schleiss, Auteur Année de publication : 2012 Article en page(s) : pp. 218-227 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Geophone  Monitoring  Steel-lined  tunnel  Wall  stiffness  Water-hammer  Wave  attenuation  Wave  speed Résumé : The effect of local drop of wall stiffness in pressurized waterways on the pressure wave speed and the wave attenuation during transients is investigated experimentally. A new signal-processing procedure to identify the presence of a weak reach is introduced and validated by physical experimentation based on assessing the pressure and vibration records acquired at both ends of a multi-reach steel test pipe. Water-hammer was generated by closing a downstream valve, whereas the weak reaches were simulated by replacing the steel portions with aluminium and PVC material. The wave speed and wave attenuation factor during transients are considered as global indicators of local and large changes in stiffness of the pipe wall. The method is capable of locating the stiffness weakness along the test pipe if one PVC reach is used. The error in estimating the position of such a reach relative to the real position of its mean value varies up to 23%. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.656838 [article] Effect of drop in pipe wall stiffness on water-hammer speed and attenuation [texte imprimé] / Fadi E. Hachem, Auteur ; Anton J. Schleiss, Auteur . - 2012 . - pp. 218-227. Hydraulique Langues : Anglais (eng) in Journal of hydraulic research > Vol. 50 N° 2 (Mars/Avril 2012) . - pp. 218-227 Mots-clés : Geophone  Monitoring  Steel-lined  tunnel  Wall  stiffness  Water-hammer  Wave  attenuation  Wave  speed Résumé : The effect of local drop of wall stiffness in pressurized waterways on the pressure wave speed and the wave attenuation during transients is investigated experimentally. A new signal-processing procedure to identify the presence of a weak reach is introduced and validated by physical experimentation based on assessing the pressure and vibration records acquired at both ends of a multi-reach steel test pipe. Water-hammer was generated by closing a downstream valve, whereas the weak reaches were simulated by replacing the steel portions with aluminium and PVC material. The wave speed and wave attenuation factor during transients are considered as global indicators of local and large changes in stiffness of the pipe wall. The method is capable of locating the stiffness weakness along the test pipe if one PVC reach is used. The error in estimating the position of such a reach relative to the real position of its mean value varies up to 23%. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.tandfonline.com/doi/abs/10.1080/00221686.2012.656838