I actually own one of these.
Posted on 08/24/2014 6:00:06 AM PDT by sukhoi-30mki
Chinese eye 'supercavitation' technology as future of underwater travel
China has moved a step closer to creating a supersonic submarine that could travel from Shanghai to San Francisco in less than two hours.
New technology developed by a team of scientists at Harbin Institute of Technology's Complex Flow and Heat Transfer Lab has made it easier for a submarine, or torpedo, to travel at extremely high speeds underwater.
Li Fengchen, professor of fluid machinery and engineering, said the team's innovative approach meant they could now create the complicated air "bubble" required for rapid underwater travel. "We are very excited by its potential," he said.
Water produces more friction, or drag, on an object than air, which means conventional submarines cannot travel as fast as an aircraft.
However, during the cold war, the Soviet military developed a technology called supercavitation, which involves enveloping a submerged vessel inside an air bubble to avoid problems caused by water drag.
A Soviet supercavitation torpedo called Shakval was able to reach a speed of 370km/h or more - much faster than any other conventional torpedoes.
In theory, a supercavitating vessel could reach the speed of sound underwater, or about 5,800km/h, which would reduce the journey time for a transatlantic underwater cruise to less than an hour, and for a transpacific journey to about 100 minutes, according to a report by California Institute of Technology in 2001.
However, supercavitation technology has faced two major problems. First, the submerged vessel has needed to be launched at high speeds, approaching 100km/h, to generate and maintain the air bubble.
Second, it is extremely difficult - if not impossible - to steer the vessel using conventional mechanisms, such as a rudder, which are inside the bubble without any direct contact with water.
As a result, its application has been limited to unmanned vessels, such as torpedoes, but nearly all of these torpedoes were fired in a straight line because they had limited ability to turn.
Li said the team of Chinese scientists had found an innovative means of addressing both problems.
Once in the water, the team's supercavitation vessel would constantly "shower" a special liquid membrane on its own surface. Although this membrane would be worn off by water, in the meantime it could significantly reduce the water drag on the vessel at low speed.
After its speed had reached 75km/h or more the vessel would enter the supercavitation state. The man-made liquid membrane on the vessel surface could help with steering because, with precise control, different levels of friction could be created on different parts of the vessel.
"Our method is different from any other approach, such as vector propulsion," or thrust created by an engine, Li said. "By combining liquid-membrane technology with supercavitation, we can significantly reduce the launch challenges and make cruising control easier."
However, Li said many problems still needed to be solved before supersonic submarine travel became feasible. Besides the control issue, a powerful underwater rocket engine still had to be developed to give the vessel a longer range. The effective range of the Russian supercavitation torpedoes, for example, was only between 11 km and 15 km.
Li said the supercavitation technology was not limited only to military use. In future, it could benefit civilian underwater transport, or water sports such as swimming.
"If a swimsuit can create and hold many tiny bubbles in water, it can significantly reduce the water drag; swimming in water could be as effortless as flying in the sky," he said.
Besides Russia, countries such as Germany, Iran and the United States have been developing vessels or weapons using supercavitation technology.
Professor Wang Guoyu, the head of the Fluid Mechanics Laboratory at Beijing Institute of Technology who is leading another state-funded research project on supercavitation, said the global research community had been troubled for decades by the lack of innovative ideas to address the huge scientific and engineering challenges.
"The size of the bubble is difficult to control, and the vessel is almost impossible to steer," he said. While cruising at high speed during supercavitation, a fin could be snapped off if it touched the water because of the liquid's far greater density.
Despite many scientists worldwide working on similar projects, the latest progress remains unclear because they are regarded as military secrets.
Wang, a member of the water armament committee of the China Society of Naval Architects and Marine Engineers, said even he had been kept in the dark about recent supercavitation developments in China.
"The primary drive still comes from the military, so most research projects are shrouded in secrecy," he said.
Rather than create an air bubble in the water through which to travel, why not just travel through the air ala an aircraft?
I think you nailed it here. The first practical use is as a weapon. If it’s already being spoken of in a civilian type application, how far along is the weapon?
Years ago I worked temporary for a short time at a company that had R&D facilities in China. They had many precautions to keep someone like me from stealing their trade secrets. I recall the irony thinking that their secrets were probably already for sale by corrupt Chinese officials.
I think they are on to something.....my farts in the bathtub are super cavatating
The Russians have had torpedoes based on this tech for years.
I don’t know about that. I’m not sure I can get a non classified answer here, but how close can you pin down a passive sonar signal at 100 miles? I cannot imagine it is good enough for a targeting solution.
Of course on the converse, I cannot see how a torpedo in a curtain of bubbles will be able to detect anything outside for guidance, and there’s no way you are going to have a tethered torpedo at this speed or range.
Guidance overall could be the limiting issue for how serious a threat this really is. Perhaps that limitation is why they have even brought it into daylight. Could be they have already determined that the military uses are impractical.
There’s a lot of interesting questions surrounding this tech.
Are they guided though? The article implies that the ability to actually maneuver is a brand new update in the tech.
Yes, the Russian torpedoes are guided.
I don't think a moose can go that fast.
At 100 miles, you'll probably have to send an anti-submarine rocket and/or ASW helo out after it. In fair seas I imagine the wake created by such supercavitating object will be very prominent and guide the pilot straight to it's source.
The bad news is that it is theoretically possible if you can pack enough propellant on a sub and still have room for crew or payload. The good news is that it would be a cinch to find... The soviets tried super cavitation torpedoes in the ‘80s but they proved impractical. It sounds scary though.
Great for torpedoes, though
I actually own one of these.
Ping! To a submarine thread. This should sound familiar to you.
Cavitation torpedoes are nothing new.
You own a tripod?
A supersonic airplane has a smooth deceleration to subsonic then to landing speed. I imagine the transition from supersonic to full stop in a submarine would be severe. As soon as you lose the supercavitation effect, that water is gonna catch hold and slow you down in a hurry.
Sounds like typical planet-killing Chicom pollution.
Yes, I know—see post 25.
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