冷却空洞の壊縮水撃の減衰とピーク周期短縮

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This paper prenents some waveform analyses on the recorded pressure fluctuation in a waterhammer by collapse of a cooling cavity and the estimated collision velocity of the liquid column to the blind end of a pipe. Real damping and peak period shortening, whose effects are alike in appearance on a graph of the change with passage of time, are separated by means of graphs of the change with passage of cycle number. The discussion on the damping is generalized using logarithmic decrements. The obtained results are that the air in the cavity strengthens the damping, its strengthening is larger early in the waterhammer, and the peak period shortening takes place rapidly not later than between the 2nd and the 3rd peaks in the case where the initial air concentration is over 30% and is almost finished by the peak periods. In addition, taking note of the ripple of bottom pressure, the physical mechanisms of those damping and peak period shortening are discussed.
一般社団法人日本機械学会の論文
1993-03-25