volume | PIER Journals

Abstract

The corrosion and anti-corrosion current of a ship modulated by the shaft can be equivalent to a time-harmonic current. Based on Maxwell's equations and boundary conditions of electromagnetic field, the Helmholtz equation of magnetic vector potential and the magnetic field expressions of the time-harmonic current in air are deduced. Then, the fast Hankel transform filtering algorithm is applied to solve the equations which contain Bessel integral. The theoretic calculation indicates that the magnetic induction intensity and its attenuation rate decrease along with the increase of distance. The three components of magnetic field have different distribution. At last, it is verified that the shaft-rate magnetic field can be observed by the experiments of carbon electrodes and ship model carried in a sea pool.

1. Lin, C. S. and S. G. Gong, Ship Physical Field, Weapon Industry Press, 2007.

2. Hoitham, P., I. Jeffery, B. Brooking, and T. Richard, "Electromagnetic signature modeling and reduction," Conference Proceeding UDT Europe, 1999.

3. Bostick, F., H. Smith, and J. Boehl, "The detection of ULF-ELF emissions from moving ships,", State Academic Educational Institutions, New York, 1977.

4. Timonov, A., I. Barrolade, and P. Holtham, "Generalized ELF propagation," Proc. Marelec 1997, 1997.

5. Wait, J. R., "Propagation of radio waves over a stratified ground," Geophysics, Vol. 18, No. 2, 1953.
doi:10.1190/1.1437893

6. Lu, X. C., S. G. Gong, and M. Sun, "Measurement of extremely low frequency field caused by shaft-rate modulated corrosion current," Acta Armamentarii, Vol. 25, No. 5, 544-546, 2004.

7. Lu, X. C., S. G. Gong, and M. Sun, "Measurement and analysis of space distribution of shaft-rate electric field of a ship," Journal of Wuhan University of Technology (Transportation Science & Engineering), Vol. 28, No. 4, 498-500, 2004.

8. Mao, W. and C. S. Lin, "The EM fields produced by a moving horizontally-directed time-harmonic dipole in two-layer media," Acta Armamentarii, Vol. 30, No. 5, 550-560, 2009.

9. Xiong, L., R. X. Jiang, and S. G. Gong, "Ship modeling method of shaft-ELFE in shallow sea," Journal of National University of Defense Technology, Vol. 36, No. 1, 98-103, 2013.

10. Zolotarevskii, Y., F. Bulygin, and A. Ponomarev, "Methods of measuring the low-frequency electric and magnetic fields of ships," Measurement Techniques, Vol. 48, No. 11, 1140-1144, 2005.
doi:10.1007/s11018-006-0035-6

11. Cheng, R., R. X. Jiang, and S. G. Gong, "Extraction of line spectrum of the ship shaft-rate electric field based on EMD and fourth-order cumulant," Ship Science and Technology, Vol. 38, No. 1, 94-98, 2016.

12. Wu, Z. Q., X. H. Zhu, and B. Li, "Modeling and measurements of alternating magnetic signatures of ships," Sensor & Transducers, Vol. 186, No. 3, 161-167, 2015.

13. Huang, F., C. S. Lin, and Z. Y. Yang, "Calculation of electric field produced by a horizontal dipole immersed in shallow sea with anisotropic seabed medium," Journal of Naval University of Engineering, Vol. 23, No. 6, 81-85, 2011.

14. Hu, P. and Z. P. Nie, "A new method to calculate Sommerfeld integral-fast hankel transform," Acta Electronica Sinica, Vol. 26, No. 3, 126-128, 1998.

15. Lei, Y. Z., Analytic Method of Time-harmonic Electromagnetic Field, Science Press, 2000.

16. Zhang, Q. G., Field Theory, Geological Publishing House, 1988.

Dr. Yuhui Sun

Dr. Chunsheng Lin

Dr. Wendou Jia

Dr. Guojun Zhai