Optimized sample shape for rotating cage flow-accelerated corrosion experiments with lead: a CFD study

In this work, the rotating cage (RC) setup, a well-known flow-accelerated corrosion testing system, was optimized for lead-cooled nuclear reactor applications using Computational Fluid Dynamics (CFD) simulations. The experimental setup is comprised of a fixed cylindrical vessel filled with a corrosive fluid and a rotating cage, which features testing samples manufactured from the material of interest. During operation, the relative motion between the samples and the fluid induces friction on the samples’ surfaces, thereby reproducing conditions found in real applications (e.g. pipes, heat exchangers and pumps). The samples normally used in the RC setup have a blunt shape with rectangular cross section. CFD analysis shows that the complex largely detached flow around this blunt shape causes a high form drag force and the power required to spin the cage becomes prohibitively large for cases with lead as a working fluid at sample speeds of 20 m/s (𝑅𝑒=2.5∗107).
A more streamlined shape of the sample, with a simple to manufacture semi-circular nose and triangular trailing edge, reduces the required power by 56% and also suppresses the unsteady massive flow separations from the corners of the sample. This makes the wall shear stresses more uniform and simplifies the interpretation of corrosion measurements.