報告書番号

L04002

タイトル（和文）

蒸気の非平衡凝縮を考慮できる3次元流体数値計算コード"MATIS-SC"の開発

タイトル（英文）

Development of CFD Code "MATIS-SC" for Steam with Nonequilibrium Condensation

概要 （図表や脚注は「報告書全文」に掲載しております）

蒸気系配管の蒸気加減弁やオリフィス，蒸気タービン等では，局所的に発生する高速な蒸気流により，圧力変動や騒音，振動疲労・減肉等が生じる可能性があるため，その流れの挙動の把握・予測は重要な研究課題となっている．これまでに当所では，蒸気加減弁の圧力脈動に関して，実験・CFD(数値流体力学)計算によりその詳細を明らかにしてきた．しかし，これまでの研究では空気を用いており，蒸気の凝縮の影響は考慮出来ていない．そこで，高圧過熱～低圧湿りの広範囲の蒸気状態を取扱え，流れ場に急激な変動を起こす非平衡凝縮も考慮できるCFDコード"MATIS-SC"を開発する事を目的とした．既存の蒸気計算モデルを組み合わせたハイブリッドモデルを新たに構築してMATIS-SCに取り込み，実験との比較を行った結果，定量的に良い一致が見られ，開発したMATIS-SCの精度が確認された．

概要 （英文）

A steam control valve, steam turbine and other plant structures in the steam piping like orifice may cause vibration, noise and erosion. For the rationalization of maintenance and management in the plant, it is important to clarify the flow characteristics in detail and the prevention method.We have researched the flow instability of the steam control valve by both the experiment and the CFD (Computational Fluid Dynamics) calculation, and clarified the mechanism of the pressure fluctuation in the middle opening condition and suggest the way to prevent the pressure fluctuation. But, as we have used the air as a working fluid in our previous research instead of the steam that is used in the power plant, we can’t consider an effect of a condensation, especially a rapid condensation from a supersaturated steam condition, called "nonequilibrium condensation". Nonequilibrium condensation causes a discontinuous property change, and this may cause the large amplitude of the fluctuation.Therefore, in this report, we developed CFD code "MATIS-SC", which can calculate the steam flow with nonequilibrium condensation by a hybrid model that is combined with a steamtable model and a classical nucleation theory model. And we confirmed a validity of MATIS-SC by a benchmark test.

報告者

キーワード