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Title:Sklopljen računski model za napoved erozije hidravličnih sistemov zaradi kavitacije in delcev : doktorska disertacija
Authors:ID Kevorkijan, Luka (Author)
ID Biluš, Ignacijo (Mentor) More about this mentor... New window
Files:.pdf DOK_Kevorkijan_Luka_2024.pdf (13,90 MB)
MD5: E66EC75001AB5C6010CACBA500E42742
 
Language:Slovenian
Work type:Doctoral dissertation
Typology:2.08 - Doctoral Dissertation
Organization:FS - Faculty of Mechanical Engineering
Abstract:Hidravlični sistemi so lahko podvrženi eroziji zaradi pojava kavitacije ali zaradi prisotnosti delcev v toku tekočine. V hidravličnih sistemih je pogosto prisotna hidrodinamska kavitacija, ki je posledica spremenjene dinamike toka, kjer pride do lokalnega povečanja hitrosti in posledičnega padca tlaka do tlaka uparjanja. Na trdni površini, ki je izpostavljena toku s kavitacijo, se lahko pojavi erozija zaradi kavitacije. Ob tem so lahko v tekočini tudi suspendirani delci, ki se ob trku s trdno površino odbijejo in pri tem oddajo del gibalne količine steni zaradi česar lahko nastopi erozija trdne površine. Ob poznavanju mehanizmov in sposobnosti modeliranja erozije zaradi kavitacije in delcev ostaja odprto področje hkratna obravnava pri modeliranju erozije zaradi obeh pojavov. Zato je bil razvit numeričen model za napoved erozije hidravličnih sistemov zaradi kavitacije in delcev. Numerični model sestoji iz modela homogene zmesi za večfazni tok, kjer je kavitacija modelirana z izvornim členom v dodatni prenosni enačbo mase pare, ki ga podaja Schnerr-Sauer kavitacijski model. Gibanje delcev je modelirano po pristopu Lagrangevega sledenja z dvosmernim sklapljanjem gibalne količine med delcem in tekočino. V komercialni program za računalniško dinamiko tekočin je preko uporabniško definiranih funkcij vpeljan model kavitacijske erozije. Erozija delcev je modelirana z McLaury modelom. Turbulenca je modelirana s tremi različnimi modeli, dvema RANS (k-ε RNG in k-ω SST) in enim hibridnim (DDES-SST). Z namenom validacije so izvedeni tudi eksperimenti s kavitacijo v toku z delci in brez delcev pri treh pretokih na primeru Venturijevega kanala, kjer erozijo na površini posredno napovemo z metodo barvnega nanosa. Narejena je primerjava rezultatov numeričnih simulacij z različnimi turbulentimi modeli, kjer je ugotovljeno, da daje najboljšo napoved DDES-SST model. Pri treh pretokih toka brez delcev in z delci je ugotovljeno zadovoljivo ujemanje med simulacijo in eksperimentom, s čimer je potrjena ustreznost numeričnega modela za napoved erozije zaradi kavitacije in zaradi delcev.
Keywords:kavitacija, delci, erozija
Place of publishing:Maribor
Place of performance:Maribor
Publisher:[L. Kevorkijan]
Year of publishing:2024
Number of pages:XIII, 159 str.
PID:20.500.12556/DKUM-87939 New window
UDC:[519.6:620.193.1]:532.5(043.3)
COBISS.SI-ID:212536579 New window
Publication date in DKUM:22.10.2024
Views:0
Downloads:32
Metadata:XML DC-XML DC-RDF
Categories:KTFMB - FS
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KEVORKIJAN, Luka, 2024, Sklopljen računski model za napoved erozije hidravličnih sistemov zaradi kavitacije in delcev : doktorska disertacija [online]. Doctoral dissertation. Maribor : L. Kevorkijan. [Accessed 17 April 2025]. Retrieved from: https://dk.um.si/IzpisGradiva.php?lang=eng&id=87939
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Licences

License:CC BY 4.0, Creative Commons Attribution 4.0 International
Link:http://creativecommons.org/licenses/by/4.0/
Description:This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
Licensing start date:02.04.2024

Secondary language

Language:English
Title:A coupled computational model for the prediction of erosion in hydraulic systems due to cavitation and particles
Abstract:Hydraulic systems can be subject to erosion due to cavitation or due to particles in the fluid flow. In hydraulic systems, hydrodynamic cavitation is often present, which is the result of altered flow dynamics, where there is a local increase in velocity and a consequent pressure drop to the vaporization pressure. Cavitation erosion can occur on a solid surface exposed to cavitation flow. At the same time, there may also be suspended particles in the liquid, which reflect after collision with a solid surface and thereby transfer part of the momentum to the wall, because of which erosion of the solid surface may occur. Knowing the mechanisms and the ability to model erosion due to cavitation and particles, the simultaneous treatment of erosion due to both phenomena remains an open field. Therefore, a numerical model was developed to predict erosion of hydraulic systems due to cavitation and particles. The numerical model consists of a homogeneous mixture model for multiphase flow, where cavitation is modelled by a source term in an additional vapor mass transfer unit given by the Schnerr-Sauer cavitation model. Particle motion is modelled using a Lagrange tracking approach with two-way coupling. The cavitation erosion model was implemented in a commercial software for computational fluid dynamics via user-defined functions. Particle erosion is modelled using the McLaury model. Turbulence is modelled with three different models, two RANS (k-ε RNG and k-ω SST) and one hybrid (DDES-SST). For validation, experiments with cavitation in a flow with and without particles at three flow rates are also carried out in a Venturi channel, where erosion on the surface is predicted by the soft paint method. A comparison of the results of numerical simulations with different turbulence models is made, where it is found that the best prediction of erosion is obtained by the DDES-SST model. Satisfactory agreement between simulation and experiment is provided for the three flow rates without particles and with particles, thus confirming the suitability of the numerical model for the prediction of cavitation and particle erosion.
Keywords:cavitation, particles, erosion


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