抄録
Air bubbling into stagnant water from (a) microscopic hole (s) was examined, which was planed to simulate nucleate boiling. The size of the hole tested was 0.05 mm and 0.10 mm. Number of the hole was one and 4×4 with 1 mm pitches. When an air ejecting velocity from the hole was low, bubbles did not agglomerate after the bubbles detached from the holes. As the ejecting velocity was increased, the bubbles became to agglomerate each other after detachment to form a coalescent bubble. Comparatively large bubbles tore off from the coalescent bubble intermittently and ascended. The bubbles never coalesced in the state clinging to the holes. The distance between the bottom wall and the coalescent bubble obtained in the present experiments, which is referred to as the thickness of the macro layer in the nucleate boiling, tended to increase with an increase in the ejecting velocity. That trend conflicted with the theory that the coalescent bubble formation is related to the Helmholtz instability between the vapor stem and ambient water where the macro layer becomes considerably thin..
