Računalna simulacija hidrauličkog udara izazvanog zatvaranjem ventila u cjevovodu zrakaste strukture

undergraduate thesis

• Title (english): Numerical simulation of the water hammer caused by closing the valve in tree-like structure pipeline
• Author: Luka Kovačić
• Mentor: Ivo Džijan (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2018-09-26, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

U ovom radu se, u programskom paketu MATLAB®, računalno simulira hidraulički udar izazvan zatvaranjem ventila na kraju cijevi kroz koju fluid struji između dva otvorena spremnika. Pri modeliranju hidrauličkog udara koristi se numerička metoda karakteristika. Računalnom simulacijom analizira se utjecaj promjene prostorno vremenskog koraka integracije, viskoznosti fluida i vremena zatvaranja ventila na promjene piezometričke visine (tlaka) i brzine u cjevovodu. Dobiveni rezultati računalne simulacije prikazani su dijagramski. Pri strujanju viskoznog fluida s vremenom dolazi do smanjivanja amplitude piezometričke visine i brzine u cijevi te promjena piezometričke visine u vremenu poprima karakteristični oblik pile. Promjena prostorno vremenskog koraka integracije nema utjecaja na rezultate simulacije nestacionarnog neviskoznog strujanja kada je CFL broj jednak jedan, dok se kada je CFL broj manji od jedan javlja negativni utjecaj numeričke difuzije. Pri brzom zatvaranju ventila maksimalne vrijednosti tlaka u sustavu jednake su onima kod trenutnog zatvaranja ventila, dok se pri sporom zatvaranju ventila maksimalne vrijednosti tlaka u sustavu smanjuju.

Abstract (english)

This paper presents, with the use of softaware package MATLAB®, computer simulation of the water hammer caused by closing the valve in the pipeline in which water flows between two open tanks. The numerical method of the characteristics is used in modeling the water hammer. Computer simulation analyzes the influence of space and time integration step, fluid viscosity, along with valve closure time on changes in the piezometric height (pressure) and velocity in the pipeline. The obtained computer simulation results are shown in diagrams. For the flow of viscous fluid the amplitude of the piezometric height and velocity in the pipe reduces over time, and the change of the piezometric height takes on the characteristic shape of the saw. The change in space and time integration step has no effect on the results of the simulation of non viscous fluid flow when the CFL number is equal to one, but when the CFL number is less than one the negative impact of the numerical diffusion occurs. The maximum pressure values in the system are the same at quick and at instant closing of the valve, as opposed to the slow closing of the valve when the maximum pressure values in the system are reduced.

• Keywords: hidraulički udar; metoda karakteristika; hidrodinamika cijevnih mreža; CFL broj
• Keywords (english): water hammer; method of the characteristics; hydrodynamics of pipe networks; CFL number
• Language: croatian
• URN:NBN: urn:nbn:hr:235:845514
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-05-22 23:06:03