09V/09VI (095/096) Nuclear Submarine Thread

[taxiya]

The calculation does not lie it only need 30 MW to push thru a bluff body with 15m Diameter it does not need length. So size is not factor here all you need is diameter and speed that it in the equation So what are you talking here?
Beside they normally also carry turbine generator as a back up system

Firstly, it is 10 (or 11 09III) meters not 15 meters. That's very big difference.

Secondly, 09 type are about the same length, so in my consideration length was NOT a factor. What I meant was 09 and LA/Virginia should have the same power requirement due to the similar sizes.

Thirdly, it is NOT 30MW on the propeller shaft in case of LA/Virginia. LA (later model) has a S6G reactor of 168 MWth, which drives TWO turbines. Considering about 1/3 efficiency, there is 56 MW mechanical power from these two turbines (break power), taking away some for electricity generation there is about at least 50MW (90%) to drive the propeller shaft (shaft power).

IF the reported 20MW class is 20MW electrical power after the generator, that is the whole power to drive both the propeller motor and deliver some electricity to equipment. Let's say 18MW (90%) left for the motor. IF there are two such turbine-generators, there will be 36MWe in total to drive the propeller shaft.

It is 36MW against 50MW shaft power for subs of the similar diameters (11 against 10). It is 72% (36/50) power driving a larger diameter (more force needed) column of water.

See the point?

So I was saying, either the 20MW class means something higher (over 25MW), or whatever sub built on it (20MW) will be slower.

P.S. backup is backup, you can not take that into consideration of the normal operation, otherwise they are not backup anymore.

 

[taxiya]

The calculation does not lie it only need 30 MW to push thru a bluff body with 15m Diameter it does not need length. So size is not factor here all you need is diameter and speed that it in the equation So what are you talking here?
Beside they normally also carry turbine generator as a back up system

The calculation did not lie, neither did I say it lied. But the calculation was only an example that is not reflective of any specific class. While I was talking specifically about LA's claimed (believe it or not) 20+ knot speed and its needed power which is greater than 30MW (50MW) that is related to any specific turbo-generator to be installed on a 09 type to reach the same 20+ knot top speed.

Here is my calculation according to the formula in the article.

V(km/h) V(knot) V(m/s) P (MW) D (M)
32.62 17.61 9.06 30 10 << the author's example
38.67 20.88 10.74 50 10 << my calculation and point related to LA/Virginia and 09III

 

[Anlsvrthng]

What is the benefit of an all electric submarine?

What can be the usage of the surplus electricity ?

I mean, the US talked lot of about it 15 years ago,but there is no visible usage of the electrical power from generators.

Rail gun shelved , drone killer lasers are nice, but not justify 50+ MWe power, what else left?

 

[Hendrik_2000]

Firstly, it is 10 (or 11 09III) meters not 15 meters. That's very big difference.

Secondly, 09 type are about the same length, so in my consideration length was NOT a factor. What I meant was 09 and LA/Virginia should have the same power requirement due to the similar sizes.

Thirdly, it is NOT 30MW on the propeller shaft in case of LA/Virginia. LA (later model) has a S6G reactor of 168 MWth, which drives TWO turbines. Considering about 1/3 efficiency, there is 56 MW mechanical power from these two turbines (break power), taking away some for electricity generation there is about at least 50MW (90%) to drive the propeller shaft (shaft power).

IF the reported 20MW class is 20MW electrical power after the generator, that is the whole power to drive both the propeller motor and deliver some electricity to equipment. Let's say 18MW (90%) left for the motor. IF there are two such turbine-generators, there will be 36MWe in total to drive the propeller shaft.

It is 36MW against 50MW shaft power for subs of the similar diameters (11 against 10). It is 72% (36/50) power driving a larger diameter (more force needed) column of water.

See the point?

So I was saying, either the 20MW class means something higher (over 25MW), or whatever sub built on it (20MW) will be slower.

P.S. backup is backup, you can not take that into consideration of the normal operation, otherwise they are not backup anymore.

36MW generator output fed into high efficiency motor some of those motor can go as high 95% so 0.95X36 MW = 36.1MW right at propeller shaft More than enough for 11 M beam which is the bean of type 93 submarine
So what is your problem I don't care how big a reactor is because we are talking the output of the generator!
Even using your Calc it come out 38 MW and not 50 MW

20MW is nominal power output the real output nobody know !

 

[Hendrik_2000]

View attachment 50443
View attachment 50444 View attachment 50445

Absorption over 300 km
100 Hz: 0.3db (50 Hz should have less absorption )
400 Hz :5.1db
1000 Hz:17.4db

Any more question ?

What water absorption has to do with submarine noise GENIUS! You are really dense The noise frequency is not the same as the motor electric frequency.Where you get that ideas University of the dummy!
There is the attenuating effect of the shaft, supporting raft etc You have to calculate the whole thing Genius capricci!
There is no single frequency It is a spectrum a series of frequencies and amplitude. Here is a typical sonar image of submarine

 

[taxiya]

36MW generator output fed into high efficiency motor some of those motor can go as high 95% so 0.95X36 MW = 36.1MW right at propeller shaft More than enough for 11 M beam which is the bean of type 93 submarine
So what is your problem I don't care how big a reactor is because we are talking the output of the generator!
Even using your Calc it come out 38 MW and not 50 MW

20MW is nominal power output the real output nobody know !

I have said that the efficiency of electrical motor is close to the efficiency of gear box. I have never take that as a disadvantage of e-drive. Never an issue.

0.95X36MW=34.2MW

34.2MW at shaft is the supposed 09 type. If that is true, it can not reach 20+ knot according to the formula that YOU put forward.

You may not care about the reactor, but big or small reactor directly determine the mechanical or electrical power generated which I am sure you care, plain physics (about 30%). Do yourself a favour, put the formula in excel. How could you get 38MW instead of 50MW to get 20+ knot?

While on the one hand you use that article to support your statement, but on the other hand when I use the same formula to give you 50MW, you don't care. I don't really care if you have a problem with me, but do you have problem with mathematics?

The only thing we may be in agreement is that (in my interpretation) 20MW class in the article designates that the engine in question actually produces about 25MW or more in standard (constant long time) condition. And my question (not to you, I know you don't know) was how should the "class" to be interpreted, and has to be interpreted in my suggestion so any outcome sub can run 20+ provided if that is what PLAN want.

 

[Hendrik_2000]

I have said that the efficiency of electrical motor is close to the efficiency of gear box. I have never take that as a disadvantage of e-drive. Never an issue.

0.95X36MW=34.2MW

34.2MW at shaft is the supposed 09 type. If that is true, it can not reach 20+ knot according to the formula that YOU put forward.

You may not care about the reactor, but big or small reactor directly determine the mechanical or electrical power generated which I am sure you care, plain physics (about 30%). Do yourself a favour, put the formula in excel. How could you get 38MW instead of 50MW to get 20+ knot?

While on the one hand you use that article to support your statement, but on the other hand when I use the same formula to give you 50MW, you don't care. I don't really care if you have a problem with me, but do you have problem with mathematics?

The only thing we may be in agreement is that (in my interpretation) 20MW class in the article designates that the engine in question actually produces about 25MW or more in standard (constant long time) condition. And my question (not to you, I know you don't know) was how should the "class" to be interpreted, and has to be interpreted in my suggestion so any outcome sub can run 20+ provided if that is what PLAN want.

Ok I make mistake 34.2 out put at the shaft assuming the diameter is 10 the calculation that I quote show 30 MW so I don't know where you got 38 or where is this 50 MW come from ?
Based on which diameter ? and what speed and where did you get this speed form reference Show me in this forum. My computer crash I don't have excel now
Do Hand calc using speed of 30mph that is the bench mark and not 30 KNot

 

[Hendrik_2000]

I think you use 90% efficiency for both motor and shaft that is a bit low for IEPS the shaft is connected directly to the motor with coupling No transmission gear
so 40 at generator output assuming motor efficiency of 95%=38 MW loss in coupling etc is 5% so multiply 38X0.95=36 so I am right.What you do is double DIPPING you already calculate loss due to motor and coupling then you calculate loss to motor again ! That is CHEATING
20 knots is the normal running speed they can go temporary higher
And the generator can run at 110% temporary

How fast can a Seawolf submarine go?
The class was the first class of American submarine to utilize pump-jet propulsors over propellers, a feature that has carried over to the newest Virginia class. As a result, a Seawolf is capable of eighteen knots on the surface, a maximum speed of35 knots underwater, and a silent running speed of about 20 knots.Oct 22, 2016

 

[Anlsvrthng]

What water absorption has to do with submarine noise GENIUS! You are really dense The noise frequency is not the same as the motor electric frequency.Where you get that ideas University of the dummy!
There is the attenuating effect of the shaft, supporting raft etc You have to calculate the whole thing Genius capricci!
There is no single frequency It is a spectrum a series of frequencies and amplitude. Here is a typical sonar image of submarine

Because they purposefully eliminated fro mteh spectrum the peaks. The commercial ships has a peak vibration frequency at (surprise, surprise ) 50 Hz .

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Let say by other ways ( I hope it is easy )
The 50 HZ generator makes 50 HZ noise.
400 Hz generator makes 400 Hz noise.
1000 Hz generator makes 1000 Hz noise.
Do you understand up to this point?

If you put together the above with the frequencies / attenuation that I calculated, then for a 50 Hz generator you need bigger and more complex vibration suppression than for a 1000 Hz. (later practically doesn't need any )

No, to make 20 MWe you need
64 tons of 50 MHz generator
8 tons of 400 Hz generator
3.2 tons of 1000 Hz generator.
Do you understand the mass-rpm(frequency )ratio of the generators?
It is within the high school knowledge.

3.2 tons of generator is half cubic meter, 8 tons is one cubic meter.
The generator on the pictures way bigger than this.
So, 50 HZ generator is very big, requiring complex noise suppression, 1000 Hz is very small, and doesn't need any noise suppression. Interesting ?

 

[Anlsvrthng]

I think you use 90% efficiency for both motor and shaft that is a bit low for IEPS the shaft is connected directly to the motor with coupling No transmission gear
so 40 at generator output assuming motor efficiency of 95%=38 MW loss in coupling etc is 5% so multiply 38X0.95=36 so I am right.What you do is double DIPPING you already calculate loss due to motor and coupling then you calculate loss to motor again ! That is CHEATING
20 knots is the normal running speed they can go temporary higher
And the generator can run at 110% temporary

How fast can a Seawolf submarine go?
The class was the first class of American submarine to utilize pump-jet propulsors over propellers, a feature that has carried over to the newest Virginia class. As a result, a Seawolf is capable of eighteen knots on the surface, a maximum speed of35 knots underwater, and a silent running speed of about 20 knots.Oct 22, 2016

C'mon. Use the knowledge.
Submarines propeller rpm is in which range?
500 rpm?
Maybe 1000 rpm?

Do you know how big is an electrical motor for that rpm at 20 MW?
And you have to put that into the narrowest point of ship.