C216 オリフィス下流における流れ加速型腐食の評価 : 3. LDVとLESによる流れ場の詳細(配管減肉評価法(2),OS5 保全・設備診断技術),動力エネルギーシステム部門20周年,次の20年への新展開)

概要

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In this study, in order to evaluate the effects of flow field on flow accelerated corrosion (FAC), an orifice flow was measured using laser Doppler velocimetry (LDV) and calculated by large eddy simulation (LES). The diameter of the pipe is 50 mm and that of the orifice is 24.3 mm; the diameter ratio is about 0.5. In LDV measurement, the flow velocity was changed from Re=2.32×10^4 to 1.20×10^4 and it was confirmed that flow structure did not depend on the flow velocity in that range. The reattachment point was about 2.5D downstream of the orifice. LES results agreed well with LDV data especially near the wall. Time-averaged wall shear stress calculated by LES decreased to almost 0 around the reattachment point, which had resulted in underestimation of the FAC rate. On the other hand, the RMS value of the wall shear stress did not decreased around the reattachment point. Hence the RMS evaluation can improves that underestimation.
一般社団法人日本機械学会の論文
2010-06-20