加速度計を用いた噴流法キャビテーション初生の検出とオリフィスキヤビテーションへの応用

摘要

In general, cavitation is an undesirable phenomenon in many cases. In order to prevent from cavitation which produces great damage in the valves and piping system of power plants, it is necessary to detect the occurrence of cavitation. In order to determine the initial stage of cavitation process, an accelerometer was used to establish the technique of estimating the incipient cavitation number by impact signals. On the other hand, in many cases, cavitation number in orifice part is denned with the average flow velocity, however, the definition with upstream and downstream pressure of flow is more useful. Therefore, the incipient cavitation number defined in general way by using a cavitating jet method was clarified and was extended to regular orifice cavitation.%管や管部品のキャビテーション壊食を回避するためrnには，キャビテーションの初生について充分に知る必rn要がある．沼知らは，開口比m＝0.05～0.4のJISrnの管内オリフィスを用いて実験を行い，キャビテーシrnョン数をσ＝2（p_d-p_v）/ρv~2（p_d:下流圧，p_v:蒸気圧，rnρ:液体密度，v:オリフィス開口部の平均流速）で定rn義したとき，初生時のキャビテーション数σ_iを肉眼rnおよび写真撮影から判定したところ，σはmによらrnずほぼ一定でσ_i＝2.5となることを報告している．