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Visualization study of film boiling onset and transition to noisy film boiling in He II

1995; Elsevier BV; Volume: 35; Issue: 10 Linguagem: Inglês

10.1016/s0011-2275(99)80003-4

1879-2235

Yasuo Katsuki, Masahide Murakami, Teruhito Iida, T. Shimazaki,

Combustion and flame dynamics

The transient boiling phenomena occurring on a planar heater in He II are visually studied to investigate the onset condition and the bifurcation criterion. The whole flow field is visualized with the aid of Schlieren and shadowgraph optics. After step-wise heating, local boiling sites appear and develop, eventually covering the heater surface, followed by the onset of film boiling. The state may further proceed to noisy boiling if the hydrostatic pressure is sufficiently large. A distinctive feature between the noisy and silent boiling states is visually confirmed in the present experiment. The onset time of film boiling as a function of heat flux is obtained via a transparent heater. It is found that there is some distinction between cases with large and small q values in the functional relationship for the onset time on q, presumably originating from different states of the precursor nucleate boiling before film boiling.