Study of the onset condition of noisy film boiling in superfluid helium

Book · Sun Dec 31 04:00:00 EST 1995

OSTI ID:187917

Murakami, Masahide; Katsuki, Yasuo ^[1]

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1. Univ. of Tsukuba (Japan). Inst. of Engineering Mechanics

Noisy film boiling appears in He II in the case of large heat flux from a heater under a large hydrostatic pressure condition. The transient boiling phenomena on a planar heater in He II are studied with the aid of Schlieren and shadow graph visualization methods while putting special emphasis on the onset condition of noisy boiling. For a pulsative heating, transient spotwise nucleate boiling first appears and develops to cover the whole heater surface with the lapse of time. Then film boiling starts and, furthermore, may proceed to noisy boiling if the hydrostatic pressure is sufficiently large. It is an interesting finding that no noisy boiling appears for sufficiently large heat flux. The frequency at which the large scale unstable motion of a large vapor bubble is seen to repeat expansion-eruption-and-crush quasi-regularly above a vapor layer on a heater is examined to investigate the dependence of the audible noise on the heat flux and the heater size. Forced transition to noisy boiling is investigated by imposing small oscillating thermal disturbance superposed on constant heat flux. It is found that the effect of oscillating thermal disturbance is so large at rather low frequencies between 0.05 and 100 Hz that the transition takes place even at the half value of the steady critical heat flux. The dependent property of noisy boiling transition on the size and orientation of a heater is also studied.

• OSTI ID: 187917
• Report Number(s): CONF-950729--
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
COOLING
CRYOGENIC FLUIDS
CRYOGENICS
EXPERIMENTAL DATA
FILM BOILING
FLOW VISUALIZATION
HELIUM II
NOISE
SUPERCONDUCTING MAGNETS