Vpliv zračnega mehurja na prehodne tlake v hidravličnem cevnem sistemu

Pekolj, Jošt (author), Perpar, Matjaž (mentor), Bergant, Anton (co-mentor)

V magistrskem delu obravnavamo vodni udar v hidravličnih cevnih sistemih z ujetim zračnim mehurjem. Raziskovali smo, kako posamezne lastnosti sistemov vplivajo na potovanje tlačnih valov po njih. Izmed vseh lastnosti je vpliv zračnega mehurja prevladujoč. V ta namen smo razvili enorazsežni numerični model za napovedovanje prehodnih tlakov med polnjenjem cevovoda, ki ima na zaprtem koncu ujet zračni mehur. Numerični model temelji na metodi karakteristik. Ugotovili smo, da uporaba ustaljenega stenskega trenja v modelu ni zadostna, zato smo za fizikalno bolj ustrezen popis v model vključili neustaljeno stensko trenje. Vpliv začetnega volumna zračnega mehurja na prehodne tlake smo opredelili s parametrično analizo. Za primere v tem delu se maksimalni tlak med polnjenjem cevovoda pojavi takrat, kadar znaša začetna dolžina zračnega mehurja med 1% in 5% dolžine cevovoda.

• Language: Slovenian
• Keywords: vodni udar, metoda karakteristik, neustaljeno trenje, zračni mehurji, numerični model, tlačni valovi, cevovodi, nihanje vode
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FS - Faculty of Mechanical Engineering
• Place of publishing: Ljubljana
• Publisher: [J. Pekolj]
• Year: 2022
• PID: 20.500.12556/RUL-138952
• UDC: 621.643:532.595(043.2)
• COBISS.SI-ID: 119305219
• Publication date in RUL: 26.08.2022

Secondary language

• Language: English
• Title: The influence of an air pocket on transient pressures in a hydraulic pipe system

Abstract

This master's thesis deals with water hammer events in a hydraulic pipe system with an entrapped air pocket. We examined how the system's characteristics affect the attenuation and shape of pressure waves. The air pocket impacts pressure waveform the most. For this reason, we developed a one-dimensional numerical model, based on the method of characteristics, that predicts transient pressures during the filling of a pipeline with an entrapped air pocket. We found that the use of steady wall friction does not describe the physical process sufficiently. Consequently, the numerical model was equipped with unsteady wall friction calculation. A parametric study was used to specify the effect of initial air pocket length on transient pressures. For the cases presented in this work, the maximum pressure during pipeline filling occurs when the initial length of the air pocket is between 1 % and 5% of the total pipe length.

• Keywords: water hammer, method of characteristics, unsteady friction, air pocket, numerical model, pressure waves, pipelines, water oscillation