The influence of peripheral electromagnetic environment on the sound of a helical-channel magnetohydrodynamics (MHD) propulsion system was investigated with experimental methods. The results show that the underwater sound of the MHD system are more susceptible by the electromagnetic environment than the airborne noise. The EMI conduction coupling has more serious influence on the sound response than the EMI radiation coupling, and the noise linearly increases with the decrease of distance to the EMI source. The shielding capacity and routing design of the cables are significant for filtering both the EMI conduction and radiation noise in the MHD performance testing.
Quieter and faster of a propulsion system is the essential desire in the areas of marine engineering and ship equipments. The magnetohydrodynamics (MHD) propulsion is considered to have this potential when operated under high magnetic field and conversion efficiency(Zhang, 2021). Compared to conventional mechanical propellers, the MHD thruster has no transmission noise and cavitation noise because of which directly accelerates the flow of the electrified seawater in channel. However, this also means that the fluid flows in a strong electromagnetic field and it will inevitably be affected by the internal 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 the external electromagnetic interference(EMI). In addition, with the increasing integration of various electronic devices in ships, more frequently conversion of the signal transmission and communication networks in actual navigation, the ship electromagnetic environment has 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 premise to suppress the electromagnetic noise efficiently.