Holographic Interferometry Studies of the Temperature Field near a Condensing Bubble
For a better understanding of the mechanism of bubble collapse, holographic interferometry combined with high-speed cinematography was used as measuring technique to study the temperature field near a condensing bubble.
To ensure well-defined reproducible conditions, experiments have been carried out by injecting single vapour bubbles into subcooled liquid through a nozzle. The experiments were performed for a range of pressure from 0.25 to 4 bar, for subcoolings from 5 to 50 K and for initial bubble diameters of about 2 mm. Freon 113 and Ethanol were used as test fluids.
To evaluate the axisymmetric temperature field around the bubble from the interference fringe field, the methods of Abel-integral are not sufficient. A correction procedure considering the light deflection caused by the local temperature gradient has been developed and applied to calculate the heat transfer coefficient. Calibration tests with a heated solid sphere showed that the experimental results agree with additional thermocouple measurements to ± 10%.
Some interferograms and the experimental results are presented.
KeywordsConvection Argon Steam Boiling Cavitation
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