Unsteady pressures influenced by trapped air pockets in water-filled pipelines
| Autor: | Anton Bergant, Angus R. Simpson, Uros Karadzic, Ling Zhou, Young-il Kim, Martin F. Lambert, AS Arris Tijsseling |
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| Přispěvatelé: | Center for Analysis, Scientific Computing & Appl., Scientific Computing |
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
pipeline apparatus
Water hammer Trapped air pocket Mechanical Engineering 0208 environmental biotechnology Flow (psychology) fluid transients 02 engineering and technology Mechanics 020801 environmental engineering Pipeline transport Discrete gas cavity model Amplitude Closure (computer programming) Mechanics of Materials Parasitic drag unsteady skin friction Boundary value problem Transient (oscillation) Geology |
| Zdroj: | Strojniški vestnik Strojniski Vestnik / Journal of Mechanical Engineering, 64(9), 501-512. Association of Mechanical Engineering and Technicians of Slovenia |
| ISSN: | 0039-2480 |
| Popis: | Trapped air pockets may cause severe operational problems in water-filled pipelines. This paper investigates the dynamic behaviour of a single trapped air pocket. A single air pocket creates distinct changes of amplitude, shape and timing of unsteady flow pressure waves when it is located at some point in a pipeline. The severity of the resulting hydraulic transients depends on the size, pressure and position of the trapped air pocket. In this paper, the air pocket is incorporated as a boundary condition in the discrete gas cavity model (DGCM) that also considers the effects of unsteady skin friction. Two distinct case studies are presented: (1) start-up test case (flow starting from rest) and (2) shut-down test case (flow stoppage). The start-up test case has been performed in the University of Montenegro pipeline apparatus (length 55 m, internal diameter 18 mm). A trapped air pocket is confined at the downstream end of the pipeline. The transient event is initiated by rapid opening of a valve positioned at the initial air/water interface. The shut-down test case has been carried out in the University of Adelaide laboratory apparatus (length 37 m, internal diameter 22 mm). A trapped gas pocket is maintained near the midpoint of the pipeline. The shut-down event is initiated by rapid closure of the downstream-end valve. Results of numerical simulations and laboratory investigations are presented and they show profound effects of unsteady skin friction on pressure histories. |
| Databáze: | OpenAIRE |
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