Doctoral Thesis

Flow Induced Vibration Fatigue Analysis of Tube Bundle

Main document 11.97 MB Appendix 95.81 kB Thesis 5.07 MB

FSIDoctoral ThesisStudent: Ing. Jiří Buzík, Ph.D.Acad. year: 2017/2018

Leader: prof. Ing. Stanislav Vejvoda, CSc.

Opponents: Ing. Dušan Vincour, Ph.D., doc. Ing. Jiří Lukavský, CSc.

The aim of the dissertation thesis is the control of the tube bundle on the cyclic fatigue caused by the flow past tube bundle. Fatigue due to flow is caused by flow-induced vibrations. Examined vibrations are caused by the mutual interaction of two phases (solid and liquid). The present work is focused mainly on the interaction of tube bundles with fluid. The current level of knowledge in this field allows to predict mainly static respectively quazi-static loading. These predictions are based on methods of comparing key vibration variables such as frequencies, amplitudes or speeds (see TEMA [1]). In this way, it is possible to determine quickly and relatively precisely the occurrence of a vibrational phenomenon, but it is not possible to quantitatively assess the effect of these vibrations on the damage of to the tube beam and to predict its lifespan, which would require the determination of the temperature field and the distribution of forces from the fluid on the beam. The aim of the work is to evaluate the-state-of-the-art, to perform a numerical simulation of the flow of fluids in the area of shell side under the inlet nozzle. Current methods of numerical analyses very well solve this problem, but at the expense of computing time, devices and expensive licences.
The benefit of this work is the use of user-defined function (UDF) as a method for simulating interaction with fluid and structure in ANSYS Fluent software. This work places great emphasis on using the current state of knowledge for verifying and validation. Verifying and validation of results include, for example, experimentally measured Reynolds and Strouhal numbers, the drag coefficients and for example magnitude of pressure coefficient around the tube. At the same time, it uses the finite element method as a tool for the stress-strain calculation of a key part on tube such as a pipe-tube joint.
Another benefit of this work is the extension of the graphical design of heat exchanger according to Poddar and Polley by vibration damages control according to the method described in TEMA [1]. In this section, the author points out the enormous influence of flow velocity on both the tube side and the shell side for design of the heat exchanger to ensure faultless operation. As an etalon of damage, the author chose a heat exchanger designated 104 from the Heat Exchanger Tube Vibration Data Bank [3]. With this heat exchanger, vibrational damage has been proven to be due to cutting of the tubes over the baffles.
The last part outlines the possibilities and limits of further work.




Defended (thesis was successfully defended)

Hodnocení známka




Study branch

Design and Process Engineering

Classification by leader
prof. Ing. Stanislav Vejvoda, CSc.

viz. posudek v pdf.

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Vyjádření školitele_Buzík.pdf 600.82 kB

Classification by opponent
Ing. Dušan Vincour, Ph.D.

viz. posudek v pdf.

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Oponentský posudek disertační práce (automaticky uloženo).pdf 182.41 kB

Classification by opponent
doc. Ing. Jiří Lukavský, CSc.

Vyjádření k tézím doktoranda Ing. Jiřího Buzíka:
„Analýza cyklické únavy trubkového svazku vlivem
proudění pracovního média“
Současný stav znalostí je popsán v úvodní části tezí, je zde vysvětlen i vliv proudění
na rizika vzniku vibrací trubek výměníků, které mohou vést až k poškození trubek. Je
zde popsán výběr typu výměníku, u něhož se prováděl výpočtový postup stanovení
vzniku vibrací.
Tím jsou splněny požadavky na zvolené řešení problematiky s hlavními výsledky
práce. V závěru jsou vyčíslené výsledky, které popisují přínos aplikace uživatelem
definovaných funkcí pro vybrané sledování pohybu v osách x a y.
Překlepy a další podněty pro srozumitelnost tezí jsou předány přímo doktorandovi.
Praha 06. 02. 2018
Doc. Ing. Jiří Lukavský, CSc.
ČVUT v Praze, FS

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Posudek_Buzík_akt.verze.pdf 215.36 kB


Flow-induced vibration, heat exchanger, tube bundle, fatigue, Karman’s vortex street, lift force, drag forces, turbulent excitation, vortex shedding, fluid-elastic instability, acoustic resonance, graphical design of heat exchanger by Poddar and Polley, finite element method, computational fluid dynamics, user define function