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.
Thank you big business for moving jobs to China...you should be ashamed, but you don’t give a F about the US.
I agree.
However neither party, is currently supporting an increase in American hiring, and a return of US jobs.
GOP needs to stop its sell-out, and become militantly pro-American.
Buy American. Bring back jobs, to America.
For real. Bring back US jobs.
Someone will eventually step up and run with this issue. If the GOP waits for the Dems to do so, it will mean the GOP no longer have any America constituency.
It will in effect, be the end of the GOP.
I want the GOP to win, and become ever stronger. That will in my opinion only happen, when the GOP becomes the party of American jobs.
Get with it GOP.
Support American jobs.
I had one of those on my Lionel set.
So true... I try to buy American as much as I can. If not American made, Canada then Mexico...but we need to get jobs back in the USA.
Not even supersonic speeds are required for this to be a big issue. Imagine ... you've managed to get the submarine up to, say 300kph or so, and are cruising along just fine. Now, let's say you need to slow down to return to port or a duty station. Making that transition from supercavitation to 'normal' underwater would be a stone bitch! Water is hard.
At that speed, a much smaller aquatic animal would also be a threat! Holy MACKERAL!
H-2-Oh. And come to think of it, if the bubble is created by from the water itself, would it be explosive by nature? Hydrogen, Oxygen?
It’s funny how this problem never concerned them when they developed supersonic torpedoes for some reason.
Spelling correction. It should be "Shkval," which is Russian for "Squall."
Well, the torpedoes aren’t actually “supersonic”, as the speed of sound is insane in water. Also, you don’t have to worry about slowing a torpedo down. It stops when it explodes. :-)
Sounds like a crock to me.
A little over 6000 miles in 100 minutes. 60 miles a minute. 3600 miles an hour. Through water. And allowing for acceleration and deceleration, perhaps a top speed of 5000 mph. Should be enough friction to make the water boil.
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