26 KB932 KB24 KB199920252010Dular, MatevžHočevar, MarkoOsterman, AljažŠirok, Braneletnik:56številka:9str. 527-534ISSN:0039-2480COBISSID:11600411URN:URN:NBN:SI:doc-AADP1W6SenAssociation of Mechanical Engineers and Technicians of Slovenia et al.Zveza strojnih inženirjev in tehnikov Slovenije et al.Strojniški vestnikinfrardeča termografijakavitacijatemperaturaultrasoundultrazvokInfrared thermography of cavitation thermal effects in water|Although the thermal effects of cavitation are believed to be negligible for cavitation in water, they were successfully experimentally measured using infrared thermography. Cavitation was generated in a small container holding about 500 ml of water. It was oscillated with ultrasonic frequencies of 42 kHz to trigger growth and collapse of bubbles. For the temperature measurementsa high-speed thermovision camera was used. It captures light in infrared spectrum with wavelength of 3-5 m. The frequency of temperature field acquisition was set to 600 Hz. A silicon glass, which is transparent in the infrared light spectrum, was attached to a cylinder and partially submerged into water. Bubbles, which tend to appear in the vicinity of solid surface, appeared on the submerged side of the glass. The visual path for the thermovision camera was: air - silicon glass - water. In this way, the temperatures on the submerged side of the silicon glass where bubble growth and implosions occur could be measured. With the applied thermographic method small but distinctive local decreases of temperature (with magnitudes up to 0.3 K), caused by cavitation, were detectedKljub temu, da se za temperaturne učinke kavitacije v vodi meni, da so zanemarljivi, so bili eksperimentalno uspešno izmerjeni z infrardečo termografijo. Kavitacija je bila vzbujana s pomočjo ultrazvoka v majhni posodi, ki je vsebovala pribl. 500 ml vode. Frekvenca ultrazvoka, ki je povzročila rast in kolaps mehurčkov, je bila 42 kHz. Temperatura je bila merjena s hitro termokamero, ki deluje v infrardečem območju od 3 do 5 m. Termokamera je temperaturna polja zajemala s frekvenco 600 Hz. Silicijevo steklo, ki je prozorno v merjenem delu IR spektra, je bilo pritrjeno na cev, delno potopljeno v vodo. Mehurčki, ki se pojavljajo v bližini trdne površine, so se pojavljali na omočeni strani stekla. Optična pot merjenega sevanja je bila tako zrak-silicijevo steklo-voda. Na ta način je bilo možno izmeriti temperature na omočeni strani silicijevega stekla, kjer je prihajalo do rasti mehurčkov in njihovih implozij. Na podlagi uporabljene termografske metode so bili izmerjena majhna, a izrazita lokalna znižanja temperature (z velikostjo do 0,3 K), ki so bila posledica kavitacijeTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaUniverza v Ljubljani, Fakulteta za strojništvo