Kavitacijska erozija v Venturijevem kanalu : magistrsko delo

Jernejc, Tilen

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Title:	Kavitacijska erozija v Venturijevem kanalu : magistrsko delo
Authors:	ID Jernejc, Tilen (Author) ID Biluš, Ignacijo (Mentor) More about this mentor...
Files:	MAG_Jernejc_Tilen_2023.pdf (7,30 MB) MD5: 080392421C0A9B42A6D41237236B6BA1
Language:	Slovenian
Work type:	Master's thesis/paper
Typology:	2.09 - Master's Thesis
Organization:	FS - Faculty of Mechanical Engineering
Abstract:	Kavitacijska erozija je ena od številnih neželenih posledic pojava kavitacije v hidravličnih strojih, saj zmanjša učinkovitost in poveča vzdrževalne stroške tovrstnih strojev. Namen magistrske naloge je bil eksperimentalno in numerično spremljati razvoj kavitacijskih struktur ter kavitacijske erozije na izpostavljeni površini v Venturijevem kanalu. Eksperimentalno delo je temeljilo na uporabi ustreznega indikatorja za zaznavanje kavitacijske erozije, pri čemer je bilo ugotovljeno, da črna akrilna barva razredčena z vodo v razmerju 1:2 daje najboljše rezultate v smislu zaznavanja poškodb. Poleg tega je bilo ugotovljeno, da največ poškodb nastane na območju separacije in kolapsa kavitacijskih struktur ter da je agresivnost kavitacije pogojena s kavitacijskim številom, saj se z manjšanjem omenjenega parametra obseg poškodb na površini znatno poveča. Časovno odvisna numerična analiza nestisljivega kavitirajočega toka je bila izvedena s programskim paketom Ansys FLUENT in je temeljila na RANS pristopu reševanja vodilnih enačb ter na uporabi RNG k-\varepsilon turbuletnega modela. Večfazni tok je bil obravnavan kot homogena zmes kapljevite in parne faze. Modeliranje kavitacije je bilo izvedeno s Schnerr-Sauer modelom. Za modeliranje kavitacijske erozije na izpostavljeni površini je bil uporabljen model Melissaris-Schenke-van Terwisga, ki temelji na hipotezi o tlačnih valovih. Primerjava rezultatov nakazuje na določeno odstopanje numerične simulacije od rezultatov eksperimentalnega dela, vendar pa je bilo kljub temu doseženo zadovoljivo ujemanje, kar potrjuje dejstvo, da je uporabljena numerična metoda primerna za nadaljnjo uporabo.
Keywords:	kavitacijska erozija, Ansys FLUENT, RANS, Schnerr-Sauer, Melissaris-Schenke-van Terwisga
Place of publishing:	Maribor
Place of performance:	Maribor
Publisher:	[T. Jernejc]
Year of publishing:	2023
Number of pages:	1 spletni vir (1 datoteka PDF (XII, 119 f.))
PID:	20.500.12556/DKUM-84226
UDC:	620.193.1(043.2)
COBISS.SI-ID:	158072323
Publication date in DKUM:	31.05.2023
Views:	574
Downloads:	153
Metadata:
Categories:	KTFMB - FS
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Licences

License:	CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International

Link:	http://creativecommons.org/licenses/by-nc-nd/4.0/
Description:	The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.
Licensing start date:	05.05.2023

Secondary language

Language:	English
Title:	Cavitation Erosion in the Venturi Section
Abstract:	Cavitation erosion is one of the many undesirable consequences of cavitation in hydraulic machinery, as it reduces the efficiency and increases the maintenance costs of such machinery. The aim of the master thesis was to experimentally and numerically monitor the evolution of cavitation structures and cavitation erosion on the exposed surface in the Venturi section. The experimental work was based on the use of suitable indicator for the detection of cavitation erosion, and it was found that black acrylic paint diluted with water in ration of 1:2 gave the best results in terms of damage detection. In addition, it was found that most damage occurs in the region of separation and collapse of cavitation structures, and that aggressiveness of cavitation is dependent on the cavitation number, as the extend of the damage on the surface increases significantly with decreasing cavitation number. The time-dependent numerical analysis of incompressible cavitating flow was performed using Ansys FLUENT and was based on the RANS approach to solving the governing equations and on the use of the RNG k-\varepsilon turbulent model. The multiphase flow was considered as a homogeneous mixture of a liquid and vapour phase. The cavitation modelling was performed using Schnerr-Sauer model. The Melissaris-Schenke-van Terwisga model, based on the pressure wave hypothesis, was used to model cavitation erosion on the exposed surface. Comparison of the results shows some deviation of the numerical simulation from the experimental results, but nevertheless a satisfactory agreement was achieved, confirming that numerical method used is suitable for further use.
Keywords:	Cavitation Erosion, Ansys FLUENT, RANS, Schnerr-Sauer, Melissaris-Schenke-van Terwisga

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