New engine sends shock waves through auto industry

[Pericles]

If they can stick it in cars they can stick it in boats.

http://en.wikipedia.org/wiki/Wave_Disk_Generator

http://www.msnbc.msn.com/id/42460541...ce-innovation/

Early days as yet, but Stephenson's "Rocket" begat "Big Boy".

P

[Dave Gudeman]

Interesting. I hope this isn't yet another great new motor design that just doesn't work out.

I can't figure out how it works, though. It looks like a rotary engine, and I've never been able to understand them either --the pressure inside the chamber somehow causes more force in one direction than the other, creating a net force in the direction of rotation.

It is clear how pistons work: the pressure causes a force on the piston head. When the force caused by gas pressure is greater than the forces in the opposite direction then the piston moves. With rotary engines the gas pressure causes a force in the direction of rotation, but it also causes a force in the opposite direction (on the "back" of the chamber wall). I don't see how there is a net force on the rotor in one direction or another from gas pressure. I mean, I believe there is a net force because the engines work --I just don't see where it comes from.

[hoytedow]

I will believe it when, but not until, I see it. =)

[Pericles]

We'll have to stack it up with EEstor and see what becomes of both, or either, or neither?

http://eestor.biz/

Orville Wright would have approved.

P

[powerabout]

is it a pulse jet motor but a rotary one?
I'l wait till I read it in an SAE journal
Might be good as an outboard

[Yellowjacket]

The concept is actually quite clever. Previously pulse detonation engines used passages in a drum to try to raise the pressure on one side of the rotor. Problem with that is that the passages don't scavenge completely, and a lot of the pressure gain from the constant volume combustion is lost at off design conditions.

In this system the combustion pulse is contained in the rotor and is diverted to a tangential velocity, which in turn drives the rotor as the pulse comes out of the rotor.

What it has over previous pulse detonation engines is that the spinning rotor builds pressure, so it can scavenge itself. The radial compressor effect provides an additional pressure, but the pressure pulse traveling up the rotor at supersonic speed has a shock wave that increases the pressure as the wave goes up the rotor. When the combustion isn't taking place the rotor passage looks like a compressor, so it creates pressure that, after the combustion process takes place can purge the passage.

As I said, very clever. Think of it as a compressor, combustor and turbine all in one rotor all in one place at different times.

This type of engine may not be well suited for off speed or off design operation, but, if it is as efficient as they say, then it has the potential to be an excellent engine for a hybrid where you can spin it up to high speed with the generator and let it run, like a single spool turbine. Not well suited at all for a conventional drive system since it might idle at more than 80% speed. Trying to clutch and shift a single spool turbine is a really difficult thing, and the speed range of the engine will likely be relatively small, that's why it makes sense for a hybrid drive.

[Frosty]

This article is being considered for deletion in accordance with wikepedias deletion policy.

Not the sort of confidence I was looking for slapped across a site I am reading for educational purposes.

A "fictional" engine of this kind will not be able to idle and pull away from the lights giving smooth acceleration through gear changing. The problem is RPM spooling and the wait needed to change a gear.

As with turbines --great for aircraft but needs RPM and gear reduction for torque with gearboxes possibly wieghing more than the engine.

[Ad Hoc]

I take it none of you have read this one?

http://articles.maritimepropulsion.c...nits52016.aspx

[powerabout]

I love this stuff
"thermal efficiency of 60% double that of existing ic engines"
a large ship engine is about 50%

Not to mention adiabatic engines, no cooling system
Cummins built some in the late 70's ( for the US gov) with the then ceramic technology and said ok lets wait till the ceramic technology is workable..still waiting

[Jimbo1490]

I really like the Quasiturbine. It's simple and very configurable for different fuels and combustion methods. Since it's a positive displacement design, you can expect plenty of useful torque.

About 15 years ago I participated in an SBIR Request for Proposal for a gun-launchable engine. My proposal was to turn a Lysholm Screw into an engine. A competing proposal using a Wankel won the bid.

Just about any architecture that can be used to compress a gas can also be turned into an engine.

Jimbo

[FAST FRED]

"Just about any architecture that can be used to compress a gas can also be turned into an engine."

Yes BUT , sadly efficiency , cost to build and maintain are not the drivers of new tech,

The AIR POLICE , still stuck with the global warming fraud are the key to what gets manufactured.

[powerabout]

the air police have made it possible over the last 30 years to actually see the sky in SoCal
and force efi engines on us all
(is that good or bad?)

[Yellowjacket]

Originally Posted by Frosty

A "fictional" engine of this kind will not be able to idle and pull away from the lights giving smooth acceleration through gear changing. The problem is RPM spooling and the wait needed to change a gear.

The folks already said it was intended for power generation or use in a hybird, where the engine can run at load and constant speed. It isn't intended for use as a directly coupled prime mover.... Remember too, that the faster you spin a generator, the smaller it is for the same power. If you are trying to generate electricty speed is good. We have a 1 megawatt alternator for a turbine that spins at 36,000 rpm, and it weighs only 200 pounds. If you want weight efficiency, spin an alternator fast.

Originally Posted by Frosty

As with turbines --great for aircraft but needs RPM and gear reduction for torque with gearboxes possibly wieghing more than the engine.

Sorry Frosty, but that simply isn't true. Let me give you an example. The Allison Model 250 turboshaft makes 500 hp, and has a gearbox that reduces the speed from the turbines 36,000 rpm down to a usable 6,000 rpm. The entire engine AND gearbox weigh only 160 pounds. An important thing about a turbine is that the power does not come in pulses like on a reciprocating engine. A typical 6 cylinder reciprocating engine has power pulse peaks that are twice the average torque. Add to that the fact that engines like diesels are low speed machines that make a lot of torque and need big robust gears to handle the torque and the power pulses. By comparison, turbine gearboxes are relatively light and don't weigh more than the engine (which is pretty darn light to start with).

[Yellowjacket]

There are literally hundreds of engine concepts out there, and as Jimbo said, just about anything that can pump air can be made into an engine. The problem with most of those concepts (and I include the Quasiturbine in this) is that there are sealing "issues" that make leakage a big probelm, or there are dynamic issues that prevent the thing from turning very fast. The good old conventional pistion engine has been refined to the point where it is very hard to beat.

If you want more power per unit weight, turbomachinery will move more air than a piston arrangement, at generally a loss of thermal efficiency.

There are some new turbine engines that are being tested that have thermal efficiency very close to a diesel, I could say more but I'd have to shoot you after I told you.

[Ad Hoc]

Originally Posted by Yellowjacket

Let me give you an example. The Allison Model 250 turboshaft makes 500 hp, and has a gearbox that reduces the speed from the turbines 36,000 rpm down to a usable 6,000 rpm. The entire engine AND gearbox weigh only 160 pounds....

I’m with Frosty on this one, as the figures you posted here don't add up to real GTs in real boats.

The last GT powered vessel we designed was spinning at circa 17-18,000RPM, so less than you quote.

Yet the g/box to drive the waterjets weighed in at close to 2 tonne.

It is a fallacy that GT, the whole installation, is lighter.