Jet engines: A nifty new engine design promises to improve combustion efficiency, thus cutting fuel consumption and reducing emissions
Posted on 09/13/2010 11:12:15 PM PDT by Islander7
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Jet engines rely on Isaac Newton’s third law of motion: for every action there is an equal and opposite reaction. When a jet is running, a compressor at the front draws in air and compresses it (see illustration). This air is guided and diffused by static blades to allow for easier ignition when it is mixed with fuel and ignited in a combustion chamber. The reaction comes in the form of rapidly expanding hot gases, which blast out of the rear of the jet and thus drive the aircraft forward. As they do so, they pass through another set of static blades which direct and accelerate the hot gases to turn a turbine. The turbine is connected by a shaft to the compressor at the front, thus turning it and keeping the whole process running.
(Excerpt) Read more at economist.com ...
Jet engines: A nifty new engine design promises to improve combustion efficiency, thus cutting fuel consumption and reducing emissions
So the exhaust exits in a rapidly-whirling vortex. What sort of wake turbulence does that portend for following planes? ...I’m thinking of the small-aircraft crash in Orange County, California, that killed several members of the family that owned the In-N-Out hamburger chain; their pilot’s crime was following too closely (meaning: not all that closely at all) to a 757: http://www.airliners.net/aviation-forums/general_aviation/read.main/3577048/
Have they built a prototype? If so, where are the independent test results?
The blast coming out of the back end would behave the same in either design, wouldn’t it?
I was wondering about that, too.
This kind of an engine will necessitate that they work in pairs, with complex feedback-control systems to balance each other’s induced turbulence.
I’m interested in seeing if there are any hard numbers to back this technology up.
I’ll bet that if it proves to be more efficient, further computer enhanced designs will intricately shape the interior including the walls for even more gains. The results could give greater understanding to dynamic wind forces.
turbulence is not an issue here since only a small diameter wake is generated..
the turbulence that affects small aircraft is generated across the outer length of the wing...in the case of a 747 could be 20 ft or so.
I am not an aeronautical engineer nor do I play one on TV.
“What sort of wake turbulence does that portend for following planes?”
Not an expert, but as I recall my readings on wake-turbulence, turb originates from the wings/wingtips, not the engine(s) exhaust. So, not much difference at least as I see it.
Well played sir. Well played.
http://ae-www.technion.ac.il/staff/pages/117
This guy? I suspected Technion from the title. They’re real heavyweights on aeronautics.
In the article link there are comments at the bottom that pretty much covers the flaws in the design and some other wacky posted ideas. Commenter ‘ntrgc89’ did a good job addressing the issues.
Me? I say hookup some inline aerators like for gasoline engines to the fuel lines to get better fuel/air mixing. It was working on the infomercial I watched and available at Pep Boys and Auto Zone off the shelf.
Mixing fuel and air outside the combustion chamber probably increases the explosion risk - getting the design to fail aircraft regulations.
Thanks for the explanation!
Once the combustion gas stream gets through the turbine, it ought to be virtually the same. After all, the engine isn’t about wasting energy.
“The blast coming out of the back end would behave the same in either design, wouldn’t it?”
I believe it would be spinning, like a bullet coming out of a rifle with spiral rifling in the barrel.
Well if it works in an infomercial then it must be true. I know that I trust every infomercial. I buy everything I see on TV. Ron Popeil or the Sham WOW! guy wouldn’t lie.
Would they?
greater efficiency = greater range for the same amount of fuel...an issue that could be of significant benefit to the IAF...
“This kind of an engine will necessitate that they work in pairs, with complex feedback-control systems to balance each other’s induced turbulence.”
You’re thinking like a twin-prop engine pilot.
Unlike a prop plane, where the prop rotation is physically connected to the plane, the rotation here (if there is any on exit — this is almost a ballistics issue, more than a aeronautical issue) would “twist” independant of the plane.
(I am an aeronatical engineer. And a former IAF pilot.)
Plus, I bet this is for centre-of-mass craft or drones, where, if the issue exists, it just doesn’t matter that much.
+++++++++++++++
The issue to me appears to be sound. I could see how this would project sound at a MUCH higher volume than a GE turbine, making it impractical for commerical use.
Don’t know, though.
Thanks Islander7.
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