抄録
The progress of the two-phase flow research can be divided into four stages. These periods are 1948-1958, 1960-1970, 1971-1979, and 1980-1990. In this 7th Report, the development of the theoretical analyses on flow oscillations and flow instabilities in natural circulation loops in boilers and nuclear reactors at the initial stage of the second period has been described. The various analytical methods, that is, the lumped-parameter model, the distributed-parameter model, the phase plane analysis, the density wave model, etc. have been introduced.
