報告書番号

L14002

タイトル（和文）

液滴衝撃エロージョンによる減肉速度の予測モデルの高度化 －液膜挙動を考慮した液膜厚さモデルの導入－

タイトル（英文）

Improvement of a Wall Thinning Rate Model for Liquid Droplet Impingement Erosion -Implementation of Liquid Film Thickness Model with Consideration of Film Behavior-

概要 （図表や脚注は「報告書全文」に掲載しております）

液滴衝突によって生じる材料表面の液膜厚さについて，液膜の発生メカニズムに基づいた液膜厚さの評価モデルを構築してLDI減肉モデルに組込み，
実機プラントにおけるLDIの評価精度の向上を実施した．
LDI減肉実験体系での液膜の流量・運動量の保存を考慮し，液膜厚さの評価モデルを構築した．
この液膜厚さモデルを組込んだ新たなLDI減肉モデルにおいて実験条件での減肉速度を評価したところ，
液膜厚さの評価に経験式を用いている従来のLDI減肉モデルよりも評価精度の改善が見られた．
更に，実機プラント条件での減肉速度評価を実施した結果，
液膜厚さモデルを組込んだ新たなLDI減肉モデルは-50％以上の精度で実測値を評価可能であり，
これまでのLDI減肉モデルに比べて評価精度も改善された．

概要 （英文）

Liquid droplet impingement erosion (LDI) is defined as an erosion phenomenon caused by high-speed droplet attack in a steam flow. Pipe wall thinning by LDI is sometimes observed in a steam piping system of a power plant. As LDI usually occurs very locally and is difficult to detect, predicting LDI location is required for safe operation of power plant systems. Therefore, we have involved in the research program to develop prediction tools that will be used easily in actual power plants.
Our previous researches developed a thinning rate evaluation model due to LDI (LDI model) and the evaluation system of the thinning rate and the thinning shape within a practically acceptable time (LDI evaluation system). Though the LDI model can include a cushioning effect of liquid film which is generated on the material surface by droplet impingement as an empirical equation with fluid parameter, the liquid film thickness is not clarified due to complex flow condition.
In this study, to improve the LDI model and the LDI evaluation system, an analytical model of the liquid film thickness was proposed with consideration of the liquid film flow behavior on the material surface. The mass balance of the liquid film was considered, and the results of CFD calculations and existing researches were applied to obtain the liquid film thickness in this model. As a result of the LDI evaluation of the new LDI model with liquid film model, improvement of the LDI model was achieved.

報告者

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