A Simulation Research On The Numerical Method Of Vessels' Magnetic Field Caused By Cathodic Protection

Cathodic protection method has been widely used to extend the life of the ship body so as to ensure the normal function of a ship hull. The protection current around the ship hull resulted from the cathodic protection system would surely bring the related magnetic field (the corrosion related magnetic field), which is generally difficult to be measured. The study shows that the corrosion related magnetic field is the main component in the far magnetic field. The controlling of the corrosion related magnetic field can make vessels safer and the ships more stable. It is also a very significant for development of intelligentized ship.In this thesis, by reading a lot of literature review, and studying the basic principle of the related magnetism, research on the corrosion related magnetic field problem is carried out based on the basic theory. A boundary integral equation for the corrosion related electric field is educed under certain conditions by using the differential equation of current and voltage, and current density of any point in the electric field can be obtained. Then the corrosion related magnetic field on the basis of Biot-Savart law is calculated, and a program for the numerical analysis of the corrosion magnetic field is developed. The research work in this thesis would provide an effective method for understanding the corrosion related magnetic field resulted from the cathodic protection system around a ship hull, and then a design for the cathodic protection system being optimal for the corrosion related magnetic field would become possible.This paper studies the numerical simulated calculation method and calculates the corrosion current density of any point in the electric field by BEM firstly. The magnetic field caused by the current is far greater than that caused by the object that can be magnetized, so we consider only the three-dimensional corrosion related magnetic field caused by the current. This paper solves the analytical solution for a simple three-directional electric cell models and some good results are obtained.