1995 Volume 44 Issue 4 Pages 226-232
A three-dimensional boundary element method (3D-BEM) was developed to estimate quantitatively catholic protection and macro-cell corrosion. To confirm the validity and usefulness of the BEM for analysis of fluid machines handling seawater with complex 3D fields, experiments and analyses were performed. A cast iron vertical pump with Zn anodes for cathodic protection, was submerged in seawater and operated. Potential distributions inside the pump and anodic currents on the Zn anodes were measured. The polarization curves of the pump material were measured as functions of flow rate, time and temperature, and the polarization characteristics were applied as boundary conditions in performing the BEM analysis. Through the analyses and experimental works, the following conclusions were obtained.
By means of appropriate modelling that takes account of the symmetry of the object being analyzed, it is possible to apply the BEM effectively to corrosion problems of machines with complex 3D fields. Furthermore, extremely high accurate analysis on potential and current density distributions can be performed for fluid machines handling seawater, by exactly ascertaining the dependency of the polarization curves on flow rate, time and temperature, and reflecting these dependencies in the boundary conditions.