Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Transient Friction in Pressurized Pipes. I: Investigation of Zielke’s Model
This paper investigates the well-known model for unsteady friction developed by Zielke in 1968. The model is based on weights of past local bulk accelerations and is analytically correct for laminar flow, but computationally demanding. Different models have been proposed using dynamic properties, typically based on instantaneous accelerations (IAB) that are more rapid in computational schemes. Unfortunately, they are not as accurate as Zielke’s model and fail to model certain types of transients. This paper points out that the water hammer transient is dominated by a periodicity varying along the pipe. Because of this, the unsteady friction calculated by the Zielke model is distributed nonuniformly along the pipe, and changes in the pipe length change the local unsteady friction. This phenomenon may explain why IAB models using calibrated coefficients to match experimental results have a large span in value for the reported coefficients. This paper will hopefully contribute to further work to find highly accurate and rapid models. The subject deserves to be brought up for discussion as a part of a total understanding of the problem.
Transient Friction in Pressurized Pipes. I: Investigation of Zielke’s Model
This paper investigates the well-known model for unsteady friction developed by Zielke in 1968. The model is based on weights of past local bulk accelerations and is analytically correct for laminar flow, but computationally demanding. Different models have been proposed using dynamic properties, typically based on instantaneous accelerations (IAB) that are more rapid in computational schemes. Unfortunately, they are not as accurate as Zielke’s model and fail to model certain types of transients. This paper points out that the water hammer transient is dominated by a periodicity varying along the pipe. Because of this, the unsteady friction calculated by the Zielke model is distributed nonuniformly along the pipe, and changes in the pipe length change the local unsteady friction. This phenomenon may explain why IAB models using calibrated coefficients to match experimental results have a large span in value for the reported coefficients. This paper will hopefully contribute to further work to find highly accurate and rapid models. The subject deserves to be brought up for discussion as a part of a total understanding of the problem.
Transient Friction in Pressurized Pipes. I: Investigation of Zielke’s Model
Storli, Pa˚l-Tore (Autor:in) / Nielsen, Torbjo&slash;rn K. (Autor:in)
Journal of Hydraulic Engineering ; 137 ; 577-584
01.05.2011
8 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Transient Friction in Pressurized Pipes. I: Investigation of Zielke's Model
| British Library Online Contents | 2011
Transient Friction in Pressurized Pipes. I: Investigation of Zielke's Model
| Online Contents | 2011
Transient Friction in Pressurized Pipes. II: Two-Coefficient Instantaneous Acceleration-Based Model
| Online Contents | 2011
Transient Friction in Pressurized Pipes. II: Two-Coefficient Instantaneous Acceleration-Based Model
| British Library Online Contents | 2011