報告書番号

L08019

タイトル（和文）

液滴衝撃エロージョン評価システムの実用性の向上 －流動・液滴評価式の導入および水/高湿り度蒸気領域への適用範囲の拡大－

タイトル（英文）

Improvement of Practical Utility of Evaluation System for Liquid Droplet Impingement Erosion - Application of Evaluation Equation for Flow and Droplet Calculation and Expansion of Applicable Region to Water/High-Wetness-Steam-

概要 （図表や脚注は「報告書全文」に掲載しております）

これまでに構築したLDI評価システムは，部分的に3次元計算を必要とする箇所があるために計算負荷が大きく，
また，高湿り度蒸気や水系配管には現状では適用できない
そこで，
①流量計算の解析的手法の導入
②水・高湿り度蒸気への適用が可能なコード"MATIS-SP2"の開発
③液滴の挙動評価の相関式化
によってシステムを高度化し，3次元計算を必要とせず，広い蒸気状態に適用可能なLDI評価システムへと改良を行った．

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.
In a power plant, pipe wall thinning by LDI is observed steam piping system.
Because LDI usually occur very locally and is difficult to detect,
a prediction of LDI location is required for the safety of the plant system.
Therefore, as ultimate objectives,
we set the development of the prediction tool of LDI location that can use in power plants easily (LDI Prediction Code).
In previous researches,
we developed LDI evaluation system, core part of LDI Prediction Code,
to organize past achievements and knowledge systematically.
However, this system needs 3 dimensional simulations to evaluate the mass flow rate and the droplet behavior
which are important parts of the system.
As 3 dimensional simulations have heavy loads, it is difficult to use as is in power plants.
In this study, we tried to develop new methods to evaluate the mass flow rate and the droplet behavior easily instead of 3 dimensional simulations
and to modify the 1 dimensional flow evaluation code MATIS SP to apply high wetness and water region.
For the mass flow rate evaluation, we assumed the flow choked at the orifice, and suggested an analytical method with experimental and computational results.
This approach agrees well with experiments and computations within acceptable range.
For the flow evaluation, we developed a new code MATIS SP2 by adopting a simplified model
that only considered pressure loss evaluation and applicable to all region of the steam and water.
And for the droplet behavior evaluation,
we conducted much simulations of the droplet behavior and suggested the correlation between droplet collision rate and flow state quantities from simulation results.
Then, we suggested new evaluation system with no 3 dimensional simulations and wide applicable region,
and compared them with previous system by LDI evaluation in model system.
As a result, we found that the new system can evaluate LDI possibility with applicable conservativeness as compared with previous system.

報告者

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