Brumby
Major
Then I am all ears. Please outline your case.
09III/09IV (093/094) Nuclear Submarine Thread
- Thread starter SinoSoldier
- Start date
Then I am all ears. Please outline your case.
duncanidaho
Junior Member
The study describes, how the soviets could reduce the noise of their submarine by using CNC-tools from Kongsberg-Toshiba to produce their propeller, which cause lesser cavitation then before.
So there is a correlation between advanced cnc-maschines and "cavitation less" propellers.
shen
Senior Member
Propeller cavitation noise is only relevant for submarines operating close to the surface. For example, diesel submarine snorkeling during transit or nuclear boat operating at periscope depth as part of a carrier battle group.
You don't have to go very deep to dramatically reduce propeller cavitation due to increase water pressure.
A transiting nuclear boat at depth doesn't need to worry about cavitation.
You don't have to go very deep to dramatically reduce propeller cavitation due to increase water pressure.
A transiting nuclear boat at depth doesn't need to worry about cavitation.
Brumby
Major
I have already given you scientific studies on the correlation between cavitation, speed and depth in an earlier post (#289). I have a better suggestion. Moored it at pierside and switch off all your machineries. You then don't have a problem with cavitation.
Brumby
Major
I personally think it is professional etiquette if you are going to quote from a 33 page document to actually reference to the page.
The study talks about how the Soviets by-passed export restrictions and sourced some milling equipment that enabled them to produce precision propellers. This needs to be read in context with the Walker spy scandal where the Soviets gained a lot of know how and technology.
The equipment is simply an enabler in the scheme of things. CNC machinery by nature performs according to input data. As the saying goes "garbage in garbage out". Without the stolen technology on propeller design, the milling equipment is no more than a big paper weight. The notion that advancement in CNC is the enabler of acoustic reduction is both misleading and plainly false. There are significant research and development that goes into acoustic propagation management. Please actually demonstrate some scientific development that demonstrate a direct correlation and not by inference.
Brumby
Major
You did not mentioned in your blog but what is your opinion on the following that supposedly is already factored into the design and development of the type 093/094 and reasons given why some China-watchers feel that it has reached improved Los Angeles acoustic level :
(i)That China Ship Scientific Research Centre has already developed relatively advanced guide vane propeller and that seven blade propeller with cruciform vortex dissipaters is already installed in the indigenous Song class and hence likely on the 093/094;
(ii)Research at Qingdao's 4808 Factory already has demonstrated sound isolation couplings to the circulation pump of fresh water system within the steam cycle;
(iii) Achievement in advanced composites materials in absorbing vibration and sound; and
(iv) Successful breakthrough in high-temperature gas-cooled reactor in propulsion .
broadsword
Brigadier
Perhaps, what they meant is that the CNC machinery was the missing link -- the concept of the ideal propeller was there, but not the execution. But even then, we have seen pictures of huge CNC milling machinery at a Chinese yard working on a propeller a few years ago. The machine was developed as part of a govt project to develop core technologies.
So the sub noise cannot be pinned down to the CNC machinery as the main cause.
thunderchief
Senior Member
Where did you get that ? For example, even those who downplay PLAN capabilities claim that 093 is equal to Victor III
To be honest, I agree - I don't think the CNC is that much of an issue. the basics of CNC is all there and the precision control is there; the only real advantage of western/japan milling machines is the optimization logic which increases production speed, material strength retention, tool life, etc.
It is like medieval armorers cutting screws, they can do it and precision is as good as modern screws, but it is really slow; until machine screw cutting was invented. Similarly, if China have the design for a good propeller, then they can build it even if the tool is inefficient at doing it. - at the end of the day, submarines are small batch production item.