Investigation of the Cavitation Aggressiveness Using PVDF Sensors

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dc.contributor Sedlář Milan, RNDr. CSc. : 65631
dc.contributor.advisor Müller Miloš, Ing. Ph.D. : 55450 Duran, Myka Mae Campo 2019-10-14T10:25:36Z 2019-10-14T10:25:36Z 2018-11-1
dc.description.abstract The assessment of aggressiveness of cavitation phenomena through direct measurement of impact forces produced by bubble collapse is studied. This was done by recording impact forces from a commercially available Polyvinylidene Fluoride (PVDF) film sensor which is exposed to cavitation generated by ultrasonic transducer equipment. The ideal number of runs which will better represent the cavitation phenomena was first identified. Results showed good repeatability of every run and that a minimum of 3 experimental trials with time duration of 15 ms are enough to get a consistent data. The preparation of the PVDF films was optimized by selecting among four PVDF films that were setup differently, namely, a PVDF film as obtained from the supplier, a PVDF film topped with one layer of tape as an added protection, PVDF film with two layers of protective tape, and lastly a PVDF film which is folded into half. The PVDF film with one layer of tape is found to be the most suitable film for aggressiveness tests in terms of sensitivity and durability from cavitation damage. This film was then subjected to three different vibration amplitudes and it showed that increasing the oscillation amplitude leads to stronger impacts. Although most impacts were seen to occur at each horn vibration period, there were prominent high impact forces observed to arise after some cycles of horn vibration. This suggests that bubbles coagulate to form large cavity and then collapse more violently at a frequency lower than the frequency of ultrasonic horn vibration. Moreover, these strong impacts occur at a frequency that decreases as the vibration amplitude is increased. The obtained impact force signal was then compared to a previously obtained pitting test data which utilized the same experimental setup as used in this study. A remarkably high difference in the order of magnitude was seen between the cumulative peak rate and pit rate indicating that not all impacts cause pits on the surface of the material. Additionally, if it is assumed that a pit is formed from a single impact force during the incubation period, then a load of 319 N is necessary to create a 0.9 m diameter pit on aluminum alloy. en
dc.format 75
dc.format.extent Ilustrace, Grafy, Tabulky None
dc.language.iso an
dc.relation.isbasedon matsymblbrack1matsymbrbrack KIM, Ki-Han, Georges CHAHINE, Jean-Pierre FRANC a Ayat KARIMI. Advanced experimental and numerical techniques for cavitation erosion prediction. Dordrecht: Springer, [2014]. Fluid mechanics and its applications, v. 106.
dc.relation.isbasedon vsp5mm matsymblbrack2matsymbrbrack Acoustic cavitation and bubble dynamics. New York, NY: Springer Berlin Heidelberg, 2017. ISBN 9783319682365.
dc.relation.isbasedon vsp5mm matsymblbrack3matsymbrbrack BRENNEN, Christopher E. Cavitation and bubble dynamics. New York: Oxford University Press, 1995. ISBN 0195094093.
dc.relation.isbasedon vsp5mm matsymblbrack4matsymbrbrack FRANC, Jean-Pierre a Jean-Marie MICHEL. Fundamentals of cavitation. Boston: Kluwer Academic Publishers, c2004. ISBN 1402022328.
dc.rights Vysokoškolská závěrečná práce je autorské dílo chráněné dle zákona č. 121/2000 Sb., autorský zákon, ve znění pozdějších předpisů. Je možné pořizovat z něj na své náklady a pro svoji osobní potřebu výpisy, opisy a rozmnoženiny. Jeho využití musí být v souladu s autorským zákonem a citační etikou cs
dc.rights A university thesis is a work protected by the Copyright Act. Extracts, copies and transcripts of the thesis are allowed for personal use only and at one?s own expense. The use of thesis should be in compliance with the Copyright Act. and the citation ethics en
dc.subject Cavitation cs
dc.subject ultrasonic cavitation cs
dc.subject PVDF Sensor cs
dc.subject Cavitation en
dc.subject ultrasonic cavitation en
dc.subject PVDF Sensor en
dc.title Investigation of the Cavitation Aggressiveness Using PVDF Sensors cs
dc.title Investigation of the Cavitation Aggressiveness Using PVDF Sensors en
dc.type diplomová práce cs 2019-5-29 Ing. 2019-05-29 2020-4-30
local.faculty Fakulta strojní cs
local.department.abbreviation KEZ
dc.identifier.signature V 201901434
local.identifier.stag 39425 Mechanical Engineering KSA
local.faculty.abbreviation FS
dc.description.mark N2301
local.note.administrators automat
local.identifier.verbis kpw06584670 Navazující
local.poradovecislo 1434 S17000401

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