Investigation of the chaotic pressure fluctuation induced by the vapor bubble oscillation in the film boiling of superfluid helium
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Superfluid helium is often used in the contemporary applications. However, the cooling capacity of superfluid helium is often deteriorated due to the appearance of the vapor phase, even boiling. Experimental investigation of the boiling phenomena of superfluid helium is carried out to explore the mechanism of it. The experimental results show that film boiling of superfluid helium is very paticular. A vapor bubble as big as the heater size is seen to be expanding and crushing on the heater surface, and also a lot of noise could be heard. The pressure fluctuation caused by the expanding and crushing of the vapor bubble is measured. The amplitude of the pressure fluctuation is very large, which shows that the film boiling is rather violent. The pressure fluctuation is also investigated by various analysis methods: FFT (Fast Fourier Transformation), auto-correlation function, re-constructing of the state-space, estimation of Lyapunov exponent and the correlation dimension. The analysis results show that the film boiling of superfluid helium has some chaotic characteristic, which will lead to the full understand of the film boiling phenomena in superfluid helium and related chaotic oscillatory phenomena.
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