Infrared Thermography of Cavitation Thermal Effects in Water

摘要

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 measurements a high-speed thermovision camera was used. It captures light in infrared spectrum with wavelength of 3 to 5 μm. 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 detected.