Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

The Influence of Electromagnetic Environment on the Sound Energy of a MHD Propulsion System
Yajun Li*, Aiwu Peng, Xiaoqiang Chen, Lingzhi Zhao

Ocean Energy Power Generation and Application Research, Institute of Electrical Engineering, Chinese Academy of Sciences
Beijing, Chinato suppress the electromagnetic noise efficiently.
The electromagnetic compatibility (EMC) is an important factor thatmust be considered in ship design (Chen, 2021). The studies on EMC
noise are often carried out from three aspects: interference sources,interference paths and sensitive objects, from which the interference
path is the most critical segment which generally includes
electromagnetic conduction noise and radiation noise. For the firstterms, the generation mechanism and equivalent modeling method of
the conducted interference noise in power supply system has beenstudied by Meng (2005) and Pan (2008), and the comparison of timedomain measurement waveform results has confirmed the correctnessof this method. Wang (2013) established the conducted EMI noise
prediction model of buck converter by using the lumped parameters
method, the model parameters were extracted by the finite element
method. Gong (2013) analyzed the conducted EMI noise of thecommon mode of the equivalent circuit based on distributed parametersand evaluated the capability of the EMI filter in the frequency band of 9kHz-30MHz. In terms of EMI radiation, an equivalent dipole model topredict the EMI noise radiated by Printed Circuit Boards (PCB) has
been proposed by Tong (2010). Mirtalaei (2014) estimated the EMI
radiation noise of the PCB by comparing the measured magnetic fieldstrength of a rectangular plane near the PCB and the analytical field
distribution results obtained by the Maxwell integral formula method
and then the equivalent current source is identified. A segmented
processing model for the common mode radiation EMI noise aboutcable lines is given by Tarateeraseth (2010). Zhao (2014) established anoise separation network for the EMI noise radiated by a motor drive.
Zhang (2010) analyzed the near-field radiated noise of the PCB loop bya magnetic field test method according to the geometric parameters of
PCB loop and the calculated equivalent current parameters.
Followed with these studies, scholars have also dedicated to develop
effective EMI suppression methods. An optimized InductanceInductance-Capacitance-Inductance (LLCL) filter topology to reducethe common mode and differential mode conducted EMI noise
generated by single-phase full bridge rectifier grid converter wasproposed Wu (2014). Wang (2011) built a method of equivalent"negative inductance" and "negative capacitance" to eliminate theparasitic EMI noise of the filter. It was also noted that Tan (2013) set

ABSTRACTThe influence of peripheral electromagnetic environment on the soundof a helical-channel magnetohydrodynamics (MHD) propulsion system
was investigated with experimental methods. The results show that theunderwater sound of the MHD system are more susceptible by theelectromagnetic environment than the airborne noise. The EMI
conduction coupling has more serious influence on the sound responsethan the EMI radiation coupling, and the noise linearly increases withthe decrease of distance to the EMI source. The shielding capacity androuting design of the cables are significant for filtering both the EMI
conduction and radiation noise in the MHD performance testing.

KEY WORDS: MHD; EMI; sound response; underwater propulsion
system; electromagnetic transmission

INTRODUCTION
Quieter and faster of a propulsion system is the essential desire in theareas of marine engineering and ship equipments. The
magnetohydrodynamics (MHD) propulsion is considered to have thispotential when operated under high magnetic field and conversion
efficiency(Zhang, 2021). Compared to conventional mechanicalpropellers, the MHD thruster has no transmission noise and cavitationnoise because of which directly accelerates the flow of the electrified
seawater in channel. However, this also means that the fluid flows in astrong electromagnetic field and it will inevitably be affected by theinternal and external electromagnetic environment with complex clutter
waves. So the sound field of the MHD channel is extremely sensitive
with both the internal electromagnetic field of the thruster and theexternal electromagnetic interference(EMI). In addition, with theincreasing integration of various electronic devices in ships, more
frequently conversion of the signal transmission and communication
networks in actual navigation, the ship electromagnetic environmenthas become extensively abominable (Zhang, 2019). Accurately
distinguish the dynamic features of different EMI factors and identify
their influence on the synthetic noise performance is the key to correct
evaluation the noise performance of the MHD system and the premise992