Rear Admiral Ma Weiming, China’s top naval engineer, is notably responsible for the development of multiple Chinese naval electromagnetic programs, including the electromagnetic catapult and railguns. He said the Chinese navy is adding a “shaftless” rim-driven pumpjet, a revolutionary and silent propulsion system to their newest attack submarine, the Type 095 SSN.
This electric drive is an attempt to leap beyond current submarine technology to technology with a long history of attempted development. This is similar to China making a stronger commitment to develop a submersible arsenal ship. China is taking technology and designs with decades of history and actually implementing them.
Previous submarine pumpjets are “shrouded propellers,” which consist of a tubular nozzle covering the propeller. By removing the shaft of the propeller, the reduction in the number of moving parts decreases the noise made by the pumpjet, as well as saving hull space. Smaller civilian rim driven electric pumpjets are easier to maintain, and have less cavitation (bubbles that form during propeller movement), which make them even more quiet.
CCTV13 had a “Focus on the interview” segment on May 30,2017. They discussed the of electric propulsion technology power of Admiral Ma Weiming. There was some discussion of the technology and spin about how China was moving beyond copying to attempt to create breakthroughs.The first few minutes of the video discussed telecommunication switching work of Zhang Ping.
Integrated Electrical Propulsion System (IEPS) turns all the output of the ship’s engine into electricity, unlike traditional propulsion designs, which convert engine and reactor output into mechanical action to turn the propeller shaft. The high electrical output can also be used to power motors for the propellers or potentially high-energy weapons. Additionally, IEPS has far fewer moving parts, making them quieter, and thus ideal for use on submarines. When coupled with quieter reactors like the Type 095’s reported natural circulation reactor, the rim-driven pumpjet and IEPS can drastically reduce the acoustic signature of any SSN.
Yamato-1 in 1991
Westinghouse, the leading U.S. advocate, gave up in the late 1960s — because the weight required to create a sufficiently powerful magnetic field would sink most ships.
In the early 1990s, Japan succeeded in making a 100 foot long 8 mph prototype surface ship called the Yamato. A group of Japanese physicists and naval architects quickly realized that the powerful magnetic coil made possible by superconductors could transform the MHD ship from old dream to new reality. Aconsortium of universities and major high-tech firms here committed about six years ago to forge ahead with a $40 million-plus project to build the propellerless MHD ship.
US and UK have tried to get electric drive to work but have not committed to it for their next generation submarines
The US Columbia submarine and UK Dreadought will not start construction for a few years and the first unit will be ready around the 2031. They have not decided to use electric drive and may choose more conventional propulsion systems.
The US and UK military and researchers have been working on electric drive propulsion tests for at least two decades. The RED-I motor used a wet gap permanent magnet motor to turn a ring of propeller blades. Two RED-I motors are mounted in free flood areas in the submarine mud tank, forward of the stern planes. The permanent magnet motor employed is large enough to permit a four feet diameter UUV to internally pass through the RED-I propulsor system in order to deploy from the stern of the submarine.
There has been general acceptance that there is potential benefit for quieter submarines using this technology but the US has opted for more conventional approaches for quieter submarines.
Various electric motors are being or have been developed for both military and non-military vessels.Those being considered for application on future U.S. Navy submarines include: permanent magnet motors (being developed by General Dynamics and Newport News Shipbuilding) and a high-temperature superconducting (HTS) synchronous motors (being developed by American Superconductors as well as General Atomics).
More recent data shows that the US Navy appears to be focusing on permanent-magnet, radial-gap electric propulsion motors (e.g. Zumwalt-class destroyers use an advanced induction motor). Permanent magnet motors are being tested on the Large Scale Vehicle II for possible application on late production Virginia class SSNs as well as future submarines. Permanent magnet motors (developed by Siemens AG) are used on Type 212 class submarines.
Reports on the Royal UK Navy Dreadnought-class submarine (i.e., the class that will replace the Vanguard class SSBNs) state that the submarines may have submarine shaftless drive (SSD) with an electric motor mounted outside the pressure hull. SSD was evaluated by the U.S. Navy as well but it remains unknown whether the Ohio class replacement will feature it. On contemporary nuclear submarines steam turbines are linked to reduction gears and a shaft rotating the propeller/pump-jet propulsor. With SSD, steam would drive electric turbogenerators (i.e., generators powered by steam turbines) that would be connected to a non-penetrating electric junction at the aft end of the pressure hull, with a watertight electric motor mounted externally (perhaps in an Integrated Motor Propulsor arrangement) powering the pump-jet propulsor, although SSD concepts without pump-jet propulsors also exist. More recent data, including an Ohio Replacement scale model displayed at the Navy League’s 2015 Sea-Air-Space Exposition, indicates that the Ohio Replacement will feature a pump-jet propulsor visually similar to the one used on Virginia class SSNs. The class will share components from the Virginia class in order to reduce risk and cost of construction
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