地磁模拟法测量舰船感应磁场的数值模拟

地磁模拟法测量舰船感应磁场具有测量速度快、实施方便等优点，但感应磁场测量精度受模拟地磁场均匀度所限制，研究其影响规律对推广应用地磁模拟法具有重要意义。从地磁模拟法原理出发，借助COMSOL多物理场有限元仿真平台，设计椭球壳解析算例来验证该仿真平台分析地磁模拟法测量感应磁场的有效性。设计某舰船算例进行数值模拟研究，定量分析了地磁模拟法测量舰船感应磁场的精度受模拟地磁场均匀度影响的变化规律，以及舰桥结构对感应磁场测量精度的影响程度。结果表明：当模拟地磁场均匀度达到91%时，感应磁场测量精度优于90%，若继续增加均匀度，则感应磁场测量精度提升效果变缓，工程效费比降低；舰桥结构对均匀度评估的影响程度为0.2%，对感应磁场测量精度的影响程度为2.7%，且当整体均匀度高于91%后，其影响程度降至2.5%，可忽略该结构对感应磁场测量的影响。研究结论为实际舰船消磁中进一步推广应用地磁模拟法提供了依据,也为地磁模拟线圈的优化设计提供了一定的参考。

Numerical Simulation of Measuring Ship's Induced Magnetic Field by Geomagnetic Field Simulation Method

Geomagnetic field simulation method has the advantages of fast measurement speed and convenient implementation, but the measurement accuracy of induced magnetic field is restricted by the uniformity of simulated geomagnetic field, so it is of great significance to study its influence law for popularizing and applying geomagnetic field simulation method. Based on the principle of geomagnetic field simulation method, with the help of COMSOL Multiphysics, an analytical example of an ellipsoidal shell is designed to verify the effectiveness of the simulation platform in analyzing geomagnetic field simulation method to measure induced magnetic field, and then a ship-type example is designed for numerical simulation. The variation law of the accuracy of measuring ship's induced magnetic field by geomagnetic field simulation method affected by the uniformity of simulated geomagnetic field and the influence of bridge structure on the measurement accuracy of induced magnetic field are quantitatively analyzed. The results show that the measurement accuracy of induced magnetic field is better than 90% when the uniformity of simulated geomagnetic field reaches 91%. If the uniformity continues to increase, the improvement effect of induced magnetic field measurement accuracy will slow down and the cost-effectiveness ratio of engineering will decrease. The influence of bridge structure on uniformity evaluation is 0.2%, and the influence degree of induced magnetic field measurement accuracy is 2.7%. When the overall uniformity is higher than 91%, its influence degree drops to 2.5%, so the influence of this structure on measuring induced magnetic field can be ignored. The research conclusion provides a basis for the further popularization and application of geomagnetic field simulation method in practical ship degaussing, and also provides a certain reference for optimization design of geomagnetic field simulation coils.