Vpliv termodinamskega učinka na agresivnost kavitacijske erozije

Petrič, David (author), Dular, Matevž (mentor)

Kavitacija je fizikalni pojav, pri katerem se zaradi lokalnega padca tlaka pojavijo mehurčki, medtem pa temperatura medija ostane približno nespremenjena. V večini primerov so učinki kavitacije nezaželeni, ki se odražajo kot hrup, vibracije, erozija, tlačne izgube, toplotne izgube. V sklopu diplomskega dela smo izdelali tlačno posodo, v kateri smo lahko nastavljali poljuben tlak. Tlak smo nastavljali tako, da smo v posodi s pomočjo kompresorja zvišali tlak, nato pa z regulacijskim ventilom nastavljali željene tlačne pogoje. Znotraj tlačne posode se je nahajala manjša posoda v katero smo natočili tekoči dušik in nato v nadaljevanju tudi hladno, ter vročo vodo. Generiranje kavitacije smo ustvarili z ultrazvočno sondo na katero smo namestili vzorec iz aluminija. Vzorec smo po vsakih 12 sekundah v tekočem dušiku, vzeli iz posode, ter ga slikali pod veliko povečavo. Slike so nam služile za nadaljnjo analizo, kjer smo opazovali poškodbe na vzorcu, ki so nastale zaradi kavitacijske erozije. Za obdelavo slik smo si pomagali s programom Inkscape in programom Matlab. S pridobljenimi rezultati smo lahko primerjali agresivnost kavitacije v hladni, ter vroči vodi in v kapljevitem dušiku.

• Language: Slovenian
• Keywords: kavitacija kavitacijska erozija tekoči dušik hladna in vroča voda poškodbe agresivnost kavitacije
• Work type: Bachelor thesis/paper
• Organization: FS - Faculty of Mechanical Engineering
• Year: 2017
• PID: 20.500.12556/RUL-98864
• Publication date in RUL: 09.12.2017

Secondary language

• Language: English
• Title: Influence of termodynamic effect on aggressiveness of cavitation erosion

Abstract

Cavitation is a physical phenomenon where, due to local pressure drop, bubbles appear, while the temperature of the medium remains approximately unchanged. In most cases the effects of cavitation are undesirable, which are reflected as noise, vibration, erosion, pressure losses, heat losses. Within this project the pressure vessel was made in which we could adjust any pressure. The pressure was adjusted by increasing the pressure in the container with the help of compressor and then the desire pressure conditions were adjusted with the control valve. Inside the pressure vessel was a small container fillled with liquid nitrogen or with hot and cold water. Cavitation was generated with ultrasonic probe on which we placed sample of aluminium. After every 12 second the sample was taken out of the container. Then we took a photos of the surface. The images were used for further analysis where we observed damage to the sample caused by cavitation erosion. For the image processing we used Inkscape and Matlab software. With the obtained results we could compare the aggressiveness of cavitation in cold, hot water and in liquid nitrogen.

• Keywords: cavitation cavitation erosion liquid nitrogen cold and hot water damage aggressiveness of cavitation