Flow accelerated corrosion (FAC) caused many accidents of nuclear energy or thermal-power-generation plants. The main cause of FAC is known as promotion of mass transfer from the wall by the turbulence accompanied by separation, reattachment, and rotating of the flow. However, the relation between mass transfer and flow field is not clarified. In this study, we investigate the relation between the flow field behind the orifice and the mass transfer rate by means of PIV measurement and electrochemical method. It is concluded that the mass transfer coefficient is scaled by the cross-sectional averaged velocity at the orifice U_D and the parameter Re_s in an interaction with a swirling flow.
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