China's Type 093 SSN has acoustic signature of 110 decibels

[Martian2]

China's Type 093 SSN has acoustic signature of 110 decibels

https://www.usnwc.edu/getattachment...ture-Nuclear-Submarine-Force_NWCR_2007-01.pdf (p. 67)

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American Innovation: China's Anti Access Strategy: Submarine Force - Part I

China's Type 093 Shang nuclear submarine has an acoustic signature of 110 decibels. This is approximately the same acoustic emission as an American Los Angeles submarine. It makes sense that both submarines have the same decibel level. Both were designed on supercomputers, built with precise five-axis CNC machine tools, and have a seven-bladed asymmetric propeller.

The Seawolf and Virginia class nuclear attack submarines are substantially quieter than the Type 093 Shang (and Los Angeles class), because they have a shrouded propeller.

The Kilo is quieter than the SSBNs and the Shang, because the Kilo is a small diesel-electric submarine. A smaller submarine requires a smaller propeller that generates less cavitation. A diesel-electric submarine also lacks a noise-generating compressor pump for a nuclear power plant. The disadvantage of a diesel-electric submarine is that a shrouded propeller is too heavy and would drain the batteries.

China's Type 094 Jin-class SSBN is ten decibels noisier than a Russian Akula-class submarine, because the hump on the Type 094 disrupts the water flow. By eliminating the hump, the Type 094 SSBN can be as silent as an Akula. By adding a shrouded propeller design, the Type 094 can be quieter than an Akula.

Ocean background noise - 90 decibels
Seawolf-class - 95 decibels (has shrouded propeller)
Virginia-class - 95 decibels (has shrouded propeller)
636 Kilo class - 105 decibels (smaller propeller, lacks coolant pump for a nuclear submarine)
Akula-class - 110 decibels (lacks shrouded propeller)
Type 093 - 110 decibels (lacks shrouded propeller)
Type 094 - 120 decibels (has hump, lacks shrouded propeller)

 

[ChineseTiger1986]

The Type 094 is on par with the Delta IV, I don't have any objection with that, since China first cares about the performance of the SLBM, then about the SSBN itself.

The SSBN will always be escorted by the SSN, so it is important to build a better performance for the SSN.

 

[Sasquatch]

@ChineseTiger1986 @S10 @Martian2

Whats the acoustic signature for the Type 095 Sub ? Western sources don't trust have already put it behind an Akula when it hasn't even come out yet.

 

[ChineseTiger1986]

Type 093B ~ 100 decibels
Type 095 ~ 95 decibels

Just my own assessment.

 

[Martian2]

Shrouded propeller and Curtiss-Wright coolant pumps mean 95-100 decibel Chinese nuclear submarines

China's Type 093 Shang-class nuclear attack submarine has an acoustic signature of 110 decibels.

There are two important upgrades that will drive future Chinese nuclear attack submarines into the 95-100 decibel range.

I have already mentioned the shrouded propeller design. Obviously, the propeller generates more cavitation at higher propeller speeds. This problem is significantly reduced by enclosing the propeller in a ducted fan.

The other major noise-generator is the nuclear reactor coolant pump. China can reverse-engineer the latest American advanced Curtiss-Wright nuclear reactor pumps for the AP1000 nuclear reactor.

China's original Type 093 nuclear attack submarine was built between 1998-2012. This means China was using Chinese technology to build its coolant pump for the submarine's nuclear reactor.

"The coin with the words, 'Commemorating the construction of the first nuclear-powered Type 093 submarine,' followed by the date. (Internet photo)"

However, Curtiss-Wright shipped highly-advanced coolant pumps for the AP1000 to China in 2012. There is also a technology-transfer agreement between Curtiss-Wright and China.

China Wants ‘Made in China’ Nuclear Reactors - WSJ

The only question is whether China has reverse-engineered the Curtiss-Wright coolant pumps and adapted them for use in new Chinese nuclear submarines.

Obama’s quiet nuclear deal with China raises proliferation concerns - The Washington Post

In conclusion, if China has implemented a shrouded propeller and Curtiss-Wright technology for coolant pumps then Chinese nuclear submarines should be in the 95 to 100 decibel range.

 

[ChineseTiger1986]

Martin, what is your assessment for China's recently deployed Type 09IIIB which also known as the Type 093G?

China reportedly completes 3 advanced nuclear attack subs — RT News

 

[ChineseTiger1986]

Now China is the leading pioneer for the fourth generation nuclear reactor, so I wonder what major leap it could help for the supercarrier and nuclear sub to improve in the future?

GCR - News - China set to build world’s first fourth-generation nuclear reactor

 

[Oldman1]

Now China is the leading pioneer for the fourth generation nuclear reactor, so I wonder what major leap it could help for the supercarrier and nuclear sub to improve in the future?

GCR - News - China set to build world’s first fourth-generation nuclear reactor

A1B reactor - Wikipedia, the free encyclopedia
If its anything like the new nuclear reactor used in the Ford class carriers which provides more power while being more compact.

Initial plans for the Gerald R. Ford-class carrier program include a two-reactor complex intended to replace the A4W reactor design used on the Nimitz-class carriers. The new A1B reactor plant is a smaller, more efficient design that provides approximately three times the electrical power of the Nimitz-class A4W reactor plant.[4] The modernization of the plant led to a higher core energy density, lower demands for pumping power, a simpler construction, and the use of modern electronic controls and displays. These changes resulted in a two-thirds reduction of watch standing requirements and a significant decrease of required maintenance.[5]

 

[ChineseTiger1986]

No need to refuel, maybe the clean nuclear power, that's definitely nice.

 

[Martian2]

Martin, what is your assessment for China's recently deployed Type 09IIIB which also known as the Type 093G?

China reportedly completes 3 advanced nuclear attack subs — RT News

Road to 95 decibels

If the Type 093G has a shrouded propeller design, that alone should bring the noise level down to the 105 decibel range.

Here's my best estimate.

Shang: 110 decibels.
-5 decibels for shrouded propeller
-5 decibels for advanced nuclear reactor coolant pump
-5 decibels for all other minor improvements combined
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95 decibels (equivalent to Virginia class)

90 decibels is ocean background noise. There really isn't much room for improvement beyond 95 decibels.

China's "Huludao Shipyard has completed the construction of three Type 093G nuclear-powered attack submarines" with a Vertical Launch System (VLS).

 

[Keel]

Very nice report @Martian2 !

These much slicker and stream-lined SSBN "tear-drop" 095 and 098 designs and the new propulsion systems will greatly reduce the noise levels since the the dates of above reports (the referenced Chinese reports included)

098:

 

[S10]

110 decibel travelling at what speed? That's the real question.

 

[Martian2]

110 decibel travelling at what speed? That's the real question.

Type 093 Shang SSN has a normal speed of 30 knots

At zero knot, the propeller is not moving. The only major sound source for an SSN is the coolant pump for the nuclear reactor. The sound generated by water flowing over the submarine hull drops to zero.

At zero knot, the Shang should be 95 decibels (e.g. 90 decibels background + 5 decibels for coolant pump).

At normal operating speed, the Shang moves all the way up to 110 decibels (e.g. 90 decibels background + 5 decibels for coolant pump + 5 decibels for propeller + 5 decibels for moving shaft and gears + 5 decibels for water-hull interface noise).

Shang range: 95 decibels (not moving) to 110 decibels (at normal speed)

As the Shang increases speed, the noise from the propeller increases. The coolant pump may increase activity to keep the nuclear reactor within normal temperature. The noise from the mechanical parts (ie. shafts and gears) will increase too. Finally, the noise from the water-submarine hull interface increases as well.

The difference is 30 knots. The decibel difference is 15 decibels. Assuming a linear relationship, a rough guess looks like the following.

Shang (not moving): 95 decibels
Shang (10 knots): 100 decibels
Shang (20 knots): 105 decibels
Shang (30 knots): 110 decibels

Note: "A change in power by a factor of 10 is a 10 dB change."
Also, a knot is 1.15 miles per hour.

This means a Shang traveling at 30 knots should be ten times louder compared to a speed of 10 knots.
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At zero knot, a diesel-electric submarine is basically at the level of background ocean noise (or 90 decibels). There is no major SSK sound source when it's not moving.

 

[Martian2]

Type 095 SSN will feature two expected upgrades to Type 093 Shang SSN

1. We expect China to move from "shaft seal pumps" to "canned motor reactor coolant pumps."

2. If they haven't already, we expect China to adopt a "digital instrumentation and control (I&C) system."

3. We might see a ducted fan to shroud the propeller.

http://www.uscc.gov/sites/default/files/8.13.08Mladineo.pdf (p. 3)