FWE with increased Throttle Range?

[PyroJoe]

Here is a shot at explaining elongated CCs that require considerable fuel flow to sustain(and air start):

[Irvine.J]

Hello Pyrojoe,
Just curious, can you substantiate your drawings by way of CFD, high speed photography or by empirical means?
Simply curious because your drawings (and what you've written) fail to make much sense to me, perhaps you could explain your process here (and in earlier drawings) in an effort to quantify your pictures and quotes.

On the contrary, sir, that is way cool and actually should be preserved as a "classic" set of observations.

Have to disagree until further quantification Larry.

Here is a highly leveraged engine:

What does that mean, exactly?

Cmon guys, be a little more critical here, I must say I disagree with your ideas here pyro.

[larry cottrill]

On the contrary, sir, that is way cool and actually should be preserved as a "classic" set of observations.

Have to disagree until further quantification Larry.

James -

Well, the key word here is "observations" -- I assume Joe is basing these on something other than just ideas. Let's see what he has to say about them.

This is why, when I speculate on something, I try to be careful to say that's what I'm doing, and maybe ask for others to validate it or prove it wrong, or whatever.

L Cottrill

[PyroJoe]

These are my viewpoints, using running characteristics of varied engines in different layouts.

"Just curious, can you substantiate your drawings by way of CFD, high speed photography or by empirical means?"

No.
High speed photography makes little sense to me, other than it is really cool to watch. Much of the chemical and thermal reactions, thermal transfers, changes in density and specific ignition points go unobserved. CFD may be useful, if the previous mentioned parameters are accounted for in the context of minute fractions of a second. No CFD for me, I'll stick with the steel models.


"Here is a highly leveraged engine:

What does that mean, exactly?"

Again, my viewpoint:
The velocity and inertia of the exhaust gases creates a low pressure swing capable of pulling some fresh fuel,air volume into the tailpipe. It is very easy to hear when this occurs. In my observations the engine noise will acquire a very distinct edge.

Where in the throttle range this occurs, depends primarily on the design. Some engines when started have already exceeded the transition, and are running leveraged from the very first starting cycle, for some the transition is at the higher end near full throttle, and yet others are very distinct in the middle of the throttle range.

This last type is the most fun to listen to. A modest sound at start, throttle up some and you can hear the transition, it takes on some "edge". Then that edge is "sharpened" the more she is throttled up. It is like the cycle has hit a wall and no matter how much you push up the throttle, she is going to push back the same. This pushing game goes on until the flame velocity is greatly exceeded, next thing you see is a two or three foot torch out the tail.


Joe

[Irvine.J]

Much of the chemical and thermal reactions, thermal transfers, changes in density and specific ignition points go unobserved. CFD may be useful, if the previous mentioned parameters are accounted for in the context of minute fractions of a second. No CFD for me, I'll stick with the steel models.

I'm not going argue with you. Just remember its here forever, as is my objection to the disregard to formal testing to guarantee no introduction of misinformation BEFORE it ended up becoming "Classic". Or whatever.

Just so you know, CFD does everything exactly as you said "If" to up there, all of that and more, and much faster then any human brain on the planet to a greater degree of accuracy, to as many tiny fractions of seconds as you tell it... hell that's why we have it. If you can do it better, Ansys want to hear from you.

[PyroJoe]

"Just remember its here forever"
I have less of a problem with this than some.

Misinformation is a computer trying to define the unlimited context of reality. Just as open to pitfalls as humans.

I regard any software only as a tool.

"Ansys want to hear from you."
I have no value of the software or the agendas behind it.

Joe

[Mike Everman]

James. Some of us like to noodle it through, pretty or not, rigorous science or not, software verification or not, making up words as we please, so chill out.

[Ghrey]

.:.


51809


.:.

[PyroJoe]

0111 0010

[PyroJoe]

Tested a slight expansion of the tail on the linear midway. There is little effect on how the engine runs and throttles. May apply a larger expansion at a later date.

Gee, wonder where a fella could put an augmentor on this engine. ha
Time to delve into augmenter design.

my best to all,
Joe

[PyroJoe]

Mike E.,
I have been reviewing some expanded tails for jets of approx. this size. I was curious if you still have the dimensions for the tail of the "Mini-Kenny, Single Intake", built several years ago.
Thanks,
Joe

[PyroJoe]

Pulled the dims from the video +/-. Falls near to the Lockwoods and good performance engines.

Two engines of 4.7" CC ID will fit within a tube 12" diameter by 47" in length. Not sure if they can be ported between the CCs. If so, it would be great to be able to start the second engine as needed.

Joe

[larry cottrill]

Joe -

I like the basic idea very much, including the shroud around the intake. The only thing about this design I don't like (and I meant to say this before now) is the square corner at the lower front. Why not put another 45-degree plate there? True, the wave motion doesn't need it -- but you're at one of the high speed gas flow points right there. I think the dead corner is doing nothing for you, and it might even be a bad reflection for a small percentage of the wave energy.

Just my gut feel -- obviously a nice motor, nonetheless. I really like the encapsulation of two in an outer shroud. You should be able to port between the chambers if arranged so the duct is kept VERY short, and it should be pretty small, I'd guess. This has often been done on turbo combustion chambers, but of course you don't have the acoustic problem to consider in that case. But, I'm sure somebody will point out the utter folly of it (that I'm just incapable of seeing ;-)

L Cottrill

[PyroJoe]

Considered time and again about the 45 degree plate.

The best way I have made peace with it is to look at it like this: the flow takes whichever radius turn it needs from the corner. If it needs to go deeper in the corner at some point, then it does, if it needs a shallow run it has that option also.

One thing is for certain, if I choose a specific angle at that point, Murphys Law will insure it is exactly wrong. ha

Last weekend I worked with a engine folded exactly in half. Used the same single 45 degree plate as the above. It would lock in, but was very fussy. Had to weld a plate between the intake and exhaust to keep them seperated. If two 45 plates would work, then it would be cool to try a cone out front, something like this one(also based on 2 CCs of 4.7"ID ......37" length plus whatever the seperator plate would be):

(Probably some un intended Freudian humor in this one)

[larry cottrill]

Joe -

I like the basic idea a LOT. The cone is (in my opinion) not as good a bend as a "wedge" of flat faces, though you can obviously make it work with careful design. I think in real life you might have trouble because of the inlets and the exhaust face in such near proximity. But, that could be cured (at least in prototype testing) by using a sizeable sheet baffle between them.

Man -- try it!

L Cottrill