Slashdot Mirror
Steam Powered Underwater Jet Engine
Bob Vila's Hammer writes "An Australian engineer, Alan Burns invented a very efficient underwater steam powered jet engine. "Steam that is produced from a petrol or gasoline fueled boiler emerges at high speed from a rearward-facing ring-shaped nozzle into a cone-shaped chamber. Shock waves created as the steam condenses are focused by the chamber to blast water out of the back. Besides powering watercraft pretty efficiently, it can also be used as an extremely robust pump. Pretty Cool."
The engine
*nix.org -- Latest article: "IBM Set to Replace AIX with Linux"
Reply or e-mail; don't vaguely moderate. Ex-O'Reilly/MIT employee, now a full-time Google employee.
The water-jet engine was invented by a New Zealander some years ago. The difference with this thing is it uses compressed steam rather than the usual propellar
This is something that would really be great in areas where there are lots of scuba divers or manatees. I have seen the results of flesh being chewed up by prop blades. Not pretty.
The bubbles are formed by steam.
"A language that doesn't affect the way you think about programming, is not worth knowing" - Alan Perlis
The design would require revamping most current hull designs to accomodate an intake for better waterflow to the motor. ...
Well, there are a lot of jet powered boats on the water right now. This is just a new way to create the pressure necessary to move the water and push the boat forwards. Guessing off the top of my head, I'd say that making a retrofit to existing jet-powered boats would not be a big problem at all.
Also, how big is the motor? It might be far too cumbersome to fit in anything less than a 20 foot boat. How much does it weigh?
Boilers can be pretty small - definitely no larger than the engines that currently take up space (and I'm referring to inboard motors as opposed to outboards). If you're referring to using a reservoir to hold the water to be boiled, why not just use the lake / river / whatever water to boil? True, salt water boils at a higher temperature, requiring more energy to create the steam, but I'm sure that if the boiler is powerful enough to creat the amount of steam it needs, it could handle that extra energy.
I bet you could also make an outboard version.
- "Nobody came out that night, not one was ever seen. But Old Man Stauf is waiting there, crazy sick and mean!"
Re-read the article, air is injected into the water intake before steam is added. The air bubbles in the water affect how the steam reacts with the water/air mixture and helps produce the shockwave critical for propulsion.
The drive was invented by Australian engineer Alan Burns and developed in Britain by engineers at Pursuit Dynamics in Royston, Hertfordshire. Last week, New Scientist witnessed a version just 20 centimetres long develop around 30 horsepower (22 kilowatts) in a test tank, enough to power a speedboat. But the company says it can be scaled up to about 300 horsepower.
... jet engines vs. propellors did for 'planes, we got a winner. But if i remember rightly (no expert here, don't hurt me), the advantages to aircraft are higher power to weight ratio and lower maintanance costs. Only one of these (the latter) seems to be really relevant in the water :( Any thoughts?
BTW when checking this with google, look at the first link i got: http://www.dkgroup.dk/hydro2.html - the "Hydro Air Drive", yet another related idea.
This is my Sig, this is my Gun. One is for Slashdot and one is for Fun.
Of course, it's also rocket powered. :)
ahh; sorry to be a dork, but this is the article on Scientific American about this stuff. Very good read.
My life in the land of the rising sun.
The air bubbles are not mixed into the water flow, but instead more or less surround it. As the bubbles (with their water payload) enter the heating chamber, they are heated and expanded by steam. The expanding bubbles displace more water, and cause the water to speed up as it moves into the exhaust chamber. As the steam gives up its heat to bubbles (and water), the steam recondenses, hence the need to transfer the heat to air beforehand.
The reason the motor has an upper scaling limit is probably because as the size of the central tube increases, the ratio of bubbles to water would decrease.
It seems likely that as in turbojet engines, the motor's efficiency would increase along with an increase in the motor's forward speed.
My understanding of the system may be lacking (I've only been able to see the diagram, just like everyone else), but I just don't see any "shock waves" occurring, being used, or needed for the engine to work.
This has been your cowardly anonymous tech reviewer, AC.
Engineers should be forced to study railroads, they were the high-tech of 150 years ago, and they actually invented many things, most especially modern telecommunication networking!!!!