Refute what, exactly? His ludicrously unsubstantiated claim that prop noise is as easy to eliminate as the mere possession of 7-axis CNC machines? His ludicrously unsubstantiated claim that there are “huge literature” out there to attenuate internal machinery noises and one just has to pick the information from the internet like peaches from a tree? That the ludicrously amateurish statement that Chinese sub hull shapes are “not much different” from any other submarine means this is a non-issue? Really? How different do hulls have to be before the noise level becomes significant? Does he even know? Do YOU know?
I’m sure according to uncritical and biased minds like yours this reads like a fanboy’s wet dream confirmation that Chinese sub tech is now Seawolf-level. For the rest of us who actually care to think through things, this is not nearly enough to constitute any kind of serious reasoning, let alone any kind of “evidence”. But I suppose the facts of the matter are not entirely relevant, at least as far as you’re concerned, amiright?
You offer nothing other than platitude Now how do you explained the fact that Soviet noise signature suddenly improve after they import the milling machine ?
Why US and cocom threw a hiss after they discover that Toshiba and Kongsberg export Milling machine to Soviet. why China cannot import CNC milling machine until today though it is how the case shooting on one own foot because China now export CNC milling machine to US
Read this article
W
hat I'd asked for was a nuclear submarine propeller, better known in the Navy as a screw. It is so secret that when a sub comes in from patrol its propeller is shrouded with a large covering, and if a sub is drydocked for any length of time, it is commonly removed and stored away from the ship for servicing and prying eyes. It is what drives a submarine quickly and quietly through the water, and it is absolutely critical to a submarine's stealth. It is an extremely high-tech piece of equipment, resulting from extensive Navy research and development, and until recently our
propeller technology exceeded the Soviet Union's by a considerable margin. As a result of this and other factors, Soviet submarines of the Cold War were noisier, and therefore easier to detect than our own. Within the context of national security and defense, as well as our nuclear deterrence policy, it is easy to see why propeller research and design have been so carefully guarded. The propellers of USS Nautilus, the first nuclear submarine, are an exception. Essentially World War II submarine propellers, they—along with the rest of the sub—are on display at the Submarine Force Museum in Groton, Connecticut, near where she was built in 1955.
But something happened to change all that. Back in the mid-1980s, the Japanese company Toshiba sold propeller milling machinery to the Soviets through the Norwegian Kongsberg firm; this and other submarine intelligence furnished by the Walker spy ring resulted in significantly quieter Soviet subs by the later part of the decade. As writer Neal Stevens wrote about the Akula-class Soviet boats, "The combined results generated a steep drop in broadband acoustic noise profiles."
The design of propeller is well known science I bet they have devoted large amount of money in research and development of the most efficient propeller
bstract
The role of cavitation research in the design of ship propellers and the influence of research on propeller design is reviewed. The historical development of research on bubble cavitation is an example of a lack of communication between research and design. Research on sheet cavitation is starting now and simplifications such as two dimensional cavitation are being made. It is argued from observations on propellers that the use of two-dimensional cavitaties is not a proper simplification to investigate sheet cavitation. An illustration is also given of the gap between the assessment of the risk of erosion on propeller models and research on erosion. Finally, the simplifications of tip vortex inception and the problems of the inception speed of propellers are discussed.
propeller - cavitation
You abviously has no clue about engineering in general when I say a huge body of literature doesn't mean Internet. Long before the advance of internet people in engineering discuss the finding of their research with publication or proceeding and do check the ASME that is they are the governing body that regulate ,publish, propagate new research and finding in engineering . There section specialized in rotating machinery and other field.
There are company that specialized in pump vibaration and its isolation . Thousands of pumps have been used in all industrial facilities all over the world for a century at least. There are consultant. specialist in this field
.
So your bravado is misplaced you just don't know a thing about pump vibration . Tell me know why pump vibrate?
Here is the primer for ship noise which is not much different from Submarine
Self-Noise Sources. Self-noise sources can be divided further into two additional categories: sonar noise and platform noise.
a. Sonar Noise. Sonar noise affects your own ship's sonar detection capability, and is discussed in Unit 7 as part of the sonar equation. Active sonar transmission signals are valuable aids for threat submarines in detecting, classifying and localizing your ship. Sonar transmissions are subject to emission control (EMCON) procedures. Since sonar noise is beyond the control of ship's force, it will not be discussed further. Control of sonar noise is NOT part of the shipboard noise control program, the purpose of the program is the control of platform noise.
b. Platform Noise. Platform noise is that noise generated by own ship other than the sonar system. Platform noise consists of radiated noise and crew generated noise. Control of this noise is the purpose of the shipboard noise control program. Platform noise is a primary concern when operating in EMCON.
3. Characteristics of Platform Noise Sources.
a. Machinery. Machinery noise originates as mechanical vibrations that are transmitted through the hull to the water, contributing to radiated noise. The vibration is also transmitted through the water and the ship's structure to own ship's sensor systems and becomes an element of self-noise. Machinery noise generates both broadband and narrowband noise.
b. Propeller Noise. Propeller noise originates outside the hull as a consequence of the propeller action and by virtue of the ship's movement through the water. The main source of propeller noise is cavitation noise caused by collapsing water vapor made by the rotating propeller blades. This noise begins above a certain speed, in the range of 9 to 15 knots, called the cavitation inception speed for ships with constant pitch propellers. For ships with variable pitch propellers, cavitation occurs at both low and high speeds; the cavitation free speeds will be in the vicinity of 12 knots, and this is usually the best speed regime for USW operations. Another important form of propeller noise is "singing" caused by propeller blade resonance. Singing generally occurs only within a narrow range of ship's speed.
c. Flow Noise (Hydrodynamic noise). External flow of water against the hull and internal flow of fluids through piping systems transmitted to the hull. External flow of water against the hull causes rattles and vibrations in hull plating and external structures. Other kinds of flow noise are the roar of the breaking bow and stern waves of a moving ship and turbulence produced by the sonar dome or towed array.
d. Electrical Noise. A source of sonar self-noise is the pickup of electrical signals from machinery and electronic equipment. This noise is called electromagnetic interference (EMI). A frequent source of EMI is arcing of brushes and motors. Electronic equipment cabinets that have high voltage switching will cause EMI unless properly grounded.
