轴转动调制腐蚀电流产生的极低频电场的测定

钢制船壳和青铜制螺旋桨之间在海水中会因电化学作用而产生腐蚀电流,该电流会从螺旋桨、经转轴、轴承、密封圈及其他一些机械线路回到船壳.随着螺旋桨转轴的转动,这个回路的电阻抗会发生周期性的变化,使得海水中的电流受到调制,从而产生极低频的电磁场由船体向外传播.文中利用船模和Ag/AgCl电极在实验室具体测量了螺旋桨转动时调制船模在海水中的腐蚀电流而产生的极低频电场.测量结果表明,由不同金属制成的船壳和螺旋桨之间的腐蚀电流经螺旋桨转动的调制后, 会产生与螺旋桨转速具有相同频率的极低频电场, 成为舰船的一个重要目标特性.

MEASUREMENT OF EXTREMELY LOW FREQUENCY FIELD CAUSED BY SHAFT-RATE MODULATED CORROSION CURRENT

Due to electrochemical effects corrosion current circulates between steel (of the hull) and bronze (of the propeller) in sea water. The current returns from the propeller, through the shaft, and through various bearings, seals, and mechanical routes back to the hull. The electrical impedance of this return path varies as the shaft rotates, causing modulation of the electrical current in the sea-water. These time-varying currents generate electric and magnetic waves that propagate from the ship. By using the ship model and Ag/AgCl electric pole, the extremely low frequency electric field produced by corrosion current modulated by shaft rotation in sea water was measured in the laboratory. Experiments show that, modulated by shaft rotation, the corrosion current between the hull and propeller, which are made of different metals will generate an ELEF at the shaft rotation rate. Therefore, the ELEF becomes an important characteristic of a ship.