What are USN "waves"?Oh I see,the wrong typewriting from "狼" to "浪" causes this mistake.It should be Sea Wolf.
09III/09IV (093/094) Nuclear Submarine Thread
- Thread starter SinoSoldier
- Start date
Think of it this way. If China's indigenous diesal subs have achieved very high noise reduction, then the most likely reason they can't achieve the same with their nuclear subs will either be the reactor and its subsystems, or the propeller, if propeller design and quality is impacted by the size of the sub. If those are the limiting factors and they have been addressed, it's not unlikely that they can get very high noise reduction from their nuclear subs too.
antiterror13
Brigadier
@Blackstone and @Hendrik_2000
I don't think Chinese objective (at least for now) is to have SSN/SSBN as quiet as the US subs ... but quiet enough to make a big headache for the US to track them. 10 years gap with the US is in my opinion good enough ... and its achievable (not yet though).
Note : I didn't say "the West" ... because the US is the benchmark, not "the West"
I don't think Chinese objective (at least for now) is to have SSN/SSBN as quiet as the US subs ... but quiet enough to make a big headache for the US to track them. 10 years gap with the US is in my opinion good enough ... and its achievable (not yet though).
Note : I didn't say "the West" ... because the US is the benchmark, not "the West"
Concerning the news tha 095 might indeed have natural circulation cooled reactor... To compare, when did other navies put into service serial production standard attack submarines with similar solution?
US did it with Seawolf class, first one launched in 1995. (They had prototype working on an one-off sub back before 1970 but political bickering lead to use of pump cooled reaction for LA class which then stuck throughout)
France had it with Rubis in 1979, though I read that in their case it was a necessity due to reactor/sub design and lack of space. Not that it was primarily meant as a noise lowering measure.
UK had it in Swiftsure, first launched in 1971, though text i read (warship design since 1945 by D. K. Brown) noted it was used for up to moderate speeds. Follow up trafalgar class used much the similar components and it also had a mix of natural circulation and pump cooling.
For Russian SSN, i read Sierra I was the first one to use it, launched in 1983. I've no idea if Akula used it as well, it was developed alongside Sierra.
Anyway, it doesn't seem to be a binary issue, though. It's very much connected to the reactor design itself, machinery design and overall efficiency. Issue in the past was how to get enough energy from the whole powerplant to attain desired speed, yet keep the size of the system small enough (as too large of powerplant inside a small sub doesn't leave much space for other important systems) So it was again a matter of noise versus speed. Ohio is, for example, said it could rely on natural cooling at almost any speed. (so i guess all but very top speeds?) That would certainly be better than Swiftsure or Typhoon classes which are quoted with natural circulation for moderate speeds only. One could often read unsubstantiated claims that French Rubis was somewhat slow. But when reading it only had natural circulation and no pumps, that sort of makes some sense.
Anyway, if 095 does get natural circulation cooling, it might mean that particular aspect of submarine design will have caught up with what operationally others had back in 1980s or so.
US did it with Seawolf class, first one launched in 1995. (They had prototype working on an one-off sub back before 1970 but political bickering lead to use of pump cooled reaction for LA class which then stuck throughout)
France had it with Rubis in 1979, though I read that in their case it was a necessity due to reactor/sub design and lack of space. Not that it was primarily meant as a noise lowering measure.
UK had it in Swiftsure, first launched in 1971, though text i read (warship design since 1945 by D. K. Brown) noted it was used for up to moderate speeds. Follow up trafalgar class used much the similar components and it also had a mix of natural circulation and pump cooling.
For Russian SSN, i read Sierra I was the first one to use it, launched in 1983. I've no idea if Akula used it as well, it was developed alongside Sierra.
Anyway, it doesn't seem to be a binary issue, though. It's very much connected to the reactor design itself, machinery design and overall efficiency. Issue in the past was how to get enough energy from the whole powerplant to attain desired speed, yet keep the size of the system small enough (as too large of powerplant inside a small sub doesn't leave much space for other important systems) So it was again a matter of noise versus speed. Ohio is, for example, said it could rely on natural cooling at almost any speed. (so i guess all but very top speeds?) That would certainly be better than Swiftsure or Typhoon classes which are quoted with natural circulation for moderate speeds only. One could often read unsubstantiated claims that French Rubis was somewhat slow. But when reading it only had natural circulation and no pumps, that sort of makes some sense.
Anyway, if 095 does get natural circulation cooling, it might mean that particular aspect of submarine design will have caught up with what operationally others had back in 1980s or so.
natural circulation is nothing new, US already achieved that with the Sturgeon, but it's at what level the rate and the quietness efficiency attained, kinda like building a HVAC system. Slayerhuahua already said 095 will be equal to early blocks of Virginia
Cavitation occurs when the pressure in the flow field of a ship or its propeller falls below the pressure of the water at that depth. So you can eliminate cavitation by "sailing" deep enough.
Cavitation erodes the ship or propeller on which it occurs and is to be avoided except in super cavitating devices where you go for high speed and use it to reduce drag.
The advantage of a pump jet is that the propeller in the duct is smaller than a free propeller and so reduces the speed differential between motor and propeller and so the size and weight of the gearing and it allows the application of noise absorbing materials near the propeller
BTW the first time I read about machining a propeller with a CNC machine was more than sixty years ago and came out of USSR.
Cavitation erodes the ship or propeller on which it occurs and is to be avoided except in super cavitating devices where you go for high speed and use it to reduce drag.
The advantage of a pump jet is that the propeller in the duct is smaller than a free propeller and so reduces the speed differential between motor and propeller and so the size and weight of the gearing and it allows the application of noise absorbing materials near the propeller
BTW the first time I read about machining a propeller with a CNC machine was more than sixty years ago and came out of USSR.
Yes pump jet fix that problem completely ? but there are a thing why right now only big nuclears submarines no SSK classes are equiped with pump jet ? the first SSK planned for have is the futur Australian Shortfin Barracuda ( A 26 and Type 218 SG don' t have also ) but very big so what is the reason ?
I have read that pump jets are supposed to be inefficient at low speeds, this would not matter in a nuclear sub that has power to spare, but in a typical SSK that spends most time going very slowly to save battery life that would be a big problem.
Either this problem has been solved or Australia intends to operate its submarines in a different way (patrolling at a relatively high speed instead of waiting in ambush) or they would not have choosen this solution.
Hendrik_2000
Lieutenant General
That is incorrect! The bubble is formed when the water attached to the propeller accelerate and causing reduction in pressure allowing bubble to form and grow. it then separate from the propeller .But because of higher static pressure of the water column above it . The bubble will collapsed and cause noise
So diving it deeper make it worse because of higher static pressure I don't know where you got this theory!
So the propeller need to reduce the speed to inhibit the bubble formation . But reducing speed decrease the thrust the solution is to make the propeller bigger not smaller and reduce friction( higher efficiency). that need complicated volute
Cavitation happened everywhere where the water get accelerated specially in the pump