Chinese Submarine News

Forest Green said:
www.twz.com

Giant Uncrewed Submarine Put Forward By Chinese Shipbuilder, Possibly Linked To Existing Design

The new uncrewed underwater vehicle concept, which is as big as some crewed types, could be tied to a still-mysterious submarine that previously emerged in China.
www.twz.com www.twz.com
Click to expand...

Actually, that sounds like a viable plan,

The design is said to be reconfigurable to conduct different missions, including attacks on enemy vessels, mine-laying, special operations support, and act as a mothership for smaller uncrewed underwater vehicles (UUV).
Click to expand...
 
TomS said:
I've long wondered why no one has seriously tried this approach, with a small reactor tied to a generator to trickle-charge a large battery. The big challenge must be to come up with a compact reactor that does not require the large crew of a full-sized system. Probably we are looking at something akin to the new commercial small modular reactors.
Click to expand...
Probably because you need pretty much the same weight of shielding whether it's a sub-megawatt reactor or a gigawatt reactor.

The gamma and neutrons spit out by the reactor all take the same amount of shielding thickness to stop because they're all the same energy. All a bigger reactor does is make more counts per minute, which means the shielding is stopping more things but they all still take the same depth of shielding to stop individually.


Hood said:
Would such a plant be noisier than a Sterling engine?
Click to expand...
Depends on design.

It'll have a tonal from the generator, but a reactor designed the right way doesn't need pumps in the primary or in the secondary. The primary uses natural circulation (convection currents), and the secondary uses scoops to ram water through the steam condensers as the ship moves forward. Size your scoops right and you can creep along at bare steerageway without needing pumps. You'd only need seawater pumps while tied up at the pier. I'm pretty sure there's a way to design the secondary loop to not require condensate pumps, it may require the steam lines to be elevated above the steam generators.

Which leaves the only noise the plant makes is water boiling in the steam generators.

Also, most Diesel-Electric boats will have that generator tonal even when operating on batteries. Batteries store DC, all the electronics are fed AC. So subs have motor-generator sets to make many kilowatts of AC, and may have two different AC frequencies as well: 50 or 60 hertz for most things, and 400 hertz for things like radar and sonar (or anything else that needs super smooth power).
 
Scott Kenny said:
Which leaves the only noise the plant makes is water boiling in the steam generators.
Click to expand...
Well, you'd still need main feed pumps, lubricating oil pumps, and auxiliary seawater pumps at the minimum, although the latter two of course apply for any submarine regardless of propulsion. In regard to motor-generators, these days (Virginia/Astute and later) nuclear submarines are switching to solid-state power conversion.
 
Vepr157 said:
Well, you'd still need main feed pumps, lubricating oil pumps, and auxiliary seawater pumps at the minimum, although the latter two of course apply for any submarine regardless of propulsion. In regard to motor-generators, these days (Virginia/Astute and later) nuclear submarines are switching to solid-state power conversion.
Click to expand...
I think you can skip feed pumps with proper design, mounting the reactor as low as possible in the hull and putting the steam generators at the same level as the condensate trays.

Auxiliary seawater pumps can likely get away with scoops as well (with the caveat about needing pumps while pierside), I don't remember there being any on the Ohios.

Lube oil pumps are often driven directly off the item they lubricate, with only a backup electrical pump for coastdown.
 
Scott Kenny said:
I think you can skip feed pumps with proper design, mounting the reactor as low as possible in the hull and putting the steam generators at the same level as the condensate trays.
Click to expand...
Condensate pumps you could theoretically do away with (although that would be dicey on a submarine designed to pitch), but feed pumps are always going to be necessary to get the condensate/feed back up to boiler pressure. No way around it in the Rankine cycle.

Scott Kenny said:
I don't remember there being any on the Ohios.
Click to expand...
I'm pretty certain they do. It would be pretty hard to cool anything otherwise.

Scott Kenny said:
Lube oil pumps are often driven directly off the item they lubricate, with only a backup electrical pump for coastdown.
Click to expand...
Typically there is one AC LO pump for normal operation with a backup DC pump, no? I've never heard of a turbine or shaft bearing geared to an LO pump. (Granted the Virginia SSTGs don't need LO because they use magnetic bearings.)
 
Vepr157 said:
Condensate pumps you could theoretically do away with (although that would be dicey on a submarine designed to pitch), but feed pumps are always going to be necessary to get the condensate/feed back up to boiler pressure. No way around it in the Rankine cycle.


I'm pretty certain they do. It would be pretty hard to cool anything otherwise.


Typically there is one AC LO pump for normal operation with a backup DC pump, no? I've never heard of a turbine or shaft bearing geared to an LO pump. (Granted the Virginia SSTGs don't need LO because they use magnetic bearings.)
Click to expand...
It's honestly been way too long, it's been more than 20 years since I set foot on a boat.

But IMO the most important part of silencing this SSPn does is not have reduction gears attached to the prop. Electric motor drives screw at whatever speed directly. call it a 0-500rpm motor.
 

Similar threads

Back
Top Bottom