Some more drawings of the FW190C

[T}{OR]

Originally Posted by swiss

He was talking about the thing under the engine, which an oil to air "heat exchange device".
The big one in the belly is the IC.
Your 2nd point is right, the first one wrong, the compressed air never goes "back" to the turbo.
Also, the turbo has to deal with way higher temp(exhaust gases) then the compressed air could ever reach.
Usually it's like:
Filter(if there is)->Turbo(rise in temp due compression)->IC->Intake

Now I have to correct you on this one.

Turbine is just that - a turbine. Turbocharger is driven by the kinetic energy of exhaust gases. It does not use the same exhaust gases to feed the engine. It sucks in the same air the normal, mechanically driven supercharger would.

The only scenario where you would use (recirculated) exhaust gases is when you want to lower emissions set by certain standard (e.g. EGR valve). And this is way too modern technology for WW2.

Originally Posted by swiss

BUT:
1.
Looking at the blueprint it looks like:
SC->IC->Turbo->Intake
Which I think is odd, very odd. I would expect the highest pressure/temp rise passing the turbo.


2.
Another funny thing is the exhaust manifold and the tubing, outside the airplane.
@10K amsl you got what, -35°?
And your flying >600kph.
Now, cooling down the exhaust gases can't really add to the efficiency, or am I wrong?


Any thoughts?

I too think this would be odd. This is the way I understood it (twice as shorter route / intake manifold):

Exhaust valves / TC + fresh air => IC (for TC) => SC > engine intake valves (or manifold if you want).

[Tempest123]

Interesting, looks simililar to a p47 in concept, i would guess that cooling down the exhaust just allowed lower temps in the turbo parts, maybe better for extended use? What was the range of the 190c, was it a short range interceptor?

[Azimech]

No, the supercharger on the DB60x series is fitted directly to the intake manifold.

The path is Air-Turbo-Intercooler-Supercharger-Intake-Exhaust-Turbo-Air

The amount of energy in the exhaust gasses is so tremendous that even flying with -50 C hardly cools it, and the pressure remains high until the gas has expanded behind the turbo.

Edit: Thor was sooner

[swiss]

Maybe because you misunderstood the drawing...

Red: Exhaust
light blue: fresh compressed hot air
blue: cooled down compressed air

I did not draw the point where the exhaust gases leve the system, nor the the actual intake.

Back to the 190:

Exhaust valves / TC + fresh air => IC (for TC) => SC > engine intake valves (or manifold if you want).

[T}{OR]

Originally Posted by swiss

Thanks thor, really, really, nice from you. Again, I am aware how a turbo system works.
Where, btw, did I suggest to return exhaust gases?

I honestly apologize if I offended you in any way. Please to re-read what you wrote (why I misunderstood you). Also, I just saw the drawing - which you added later on by editing the post.

Originally Posted by swiss

Maybe because you misunderstood the drawing...

Red: Exhaust
light blue: fresh compressed hot air
blue: cooled down compressed air

I did not draw the point where the exhaust gases leve the system, nor the the actual intake.

What you drew looks alright by me. Azimech also understood it like I did.

[swiss]

Great, we finally agree.


But I still dont get Turbo->SC.
It says they used an additional turbo, but nowhere a modified charger, which they probably had to, since it had to deal with altered pressure.
Also, I thought SC work with lower pressure compared to turbos.
Plus, the SC is fed with (still)hot air and heats its up again.
I have some doubts concerning efficiency, what is the SC's purpose? Reduce IC lag?

I guess I'll have to do some research.

looks similar to a p47 in concept,

Not really, the P47 just had a turbo/IC setup - but they called it "exhaust-supercharger" which adds to the confusion.
That is according to the infos I just found. I'd be more than happy to hear about a combo system.

[koivis]

Originally Posted by swiss

Not really, the P47 just had a turbo/IC setup - but they called it "exhaust-supercharger" which adds to the confusion.

Well, actually it was a similar system to Fw 190C. As far as I know, every P&W R-2800 made also had an internal supercharger mounted directly behind the engine, driven by the crankshaft. The confusing thing here is, that while the air from turbocharger went indeed to the carburetor, from there it continued to the supercharger! After that, it's of course going to cylinders. Some pictures to clarify:

P-47 Engine, supercharger in blue colour, carburetor is the black thing on top of it:


Another view, showing the duct leading to carb, blue object is the supercharger:


Rolls Royce Merlin had almost the same setup (I think most WW2 engines did), except it had an liquid cooled intercooler as the last thing before the intake. Also of note here (two stage version) is that the air is cooled between the stages too!


Hope this helps, I get sometimes confused with this technology too.

[T}{OR]

Originally Posted by swiss

Great, we finally agree.

Yeah.

Originally Posted by swiss

But I still dont get Turbo->SC.
It says they used an additional turbo, but nowhere a modified charger, which they probably had to, since it had to deal with altered pressure.
Also, I thought SC work with lower pressure compared to turbos.
Plus, the SC is fed with (still)hot air and heats its up again.
I have some doubts concerning efficiency, what is the SC's purpose? Reduce IC lag?

I guess I'll have to do some research.

I am guessing it has something to do along the lines what Azimech wrote:

Originally Posted by Azimech

... It seems they had it right to keep the supercharger attached to the engine, since the turbo takes load of from it, decreasing the load on the engine to drive the supercharger, and being able to boost even more. It was probably even coupled with the barometric device that regulated the variable hydraulic clutch. Anyway I would've chosen that spot due to the CoG.

On the second thought...

Originally Posted by koivis

Well, actually it was a similar system to Fw 190C. As far as I know, every P&W R-2800 made also had an internal supercharger mounted directly behind the engine, driven by the crankshaft. The confusing thing here is, that while the air from turbocharger went indeed to the carburetor, from there it continued to the supercharger! After that, it's of course going to cylinders.

Now that makes no sense. A supercharger compressing a mixture of air and fuel?! What was the compression ratio inside the cylinders then (ε)?

Unless... Doh! But of course. I am 90% sure this is a Pressure Carburetor since allied engines didn't have fuel injection. So you could say this was a form of fuel injection - to prevent negative G cutouts. Or at least has something to do with how Pressure Carburetor functions.

Question here is - is Fw-190C using proper mechanical fuel injection or a Pressure Carburetor as well?

Originally Posted by koivis

Rolls Royce Merlin had almost the same setup (I think most WW2 engines did), except it had an liquid cooled intercooler as the last thing before the intake. Also of note here (two stage version) is that the air is cooled between the stages too!

As it should be, or else you risk injecting too hot air inside the cylinder. Merlins had to have a mechanically driven SC because their exhaust was - almost non-existent.


A very interesting thread if I may say so!

[T}{OR]

After skimming through this document:

http://faculty.sdmiramar.edu/wnorth/249/249six.pdf

I am not so sure what this last supercharger is for. If someone can provide more accurate drawings maybe it will be more clear. I can't make out exactly how it works from the pictures posted.

And the added bonus is the fact it is already and hour past midnight here. So I will continue this discussion tomorrow.

EDIT: Something like this:

[koivis]

To confuse myself I and others even more, I present you the ultimate in piston engine technology, actually the most powerful piston engine to have ever powered an aircraft:

Dobrynin VD-4K

I kinda feel sorry for air when it faces this 24-cylinder, six-bank, four-row, 59,5 liter monster, as it has to go through a most confusing route:

Air from intake goes to turbo, turbo blows air into a two-stage, variable geometry supercharger, air goes to cylinders (I assume it had direct injection). Exhaust gases go trough three "blowdown" turbines between the cylinder banks (one for each 8 cylinders = 2 banks), then continues towards the back to go turn the aforementioned turbosupercharger. Probably, after this point, the exhaust gases don't have anything more to give...

The blowdown turbines are mechanically connected to crankshaft, in this case adding some 700 free horsepower. Of course, there is also the two-stage supercharger, and all this most likely needs whole lotta intercooling and other extra piping. I could draw a picture of that, but it's late, and I think that would take some time.

Sources:
http://en.wikipedia.org/wiki/Dobrynin_VD-4K
http://de.wikipedia.org/wiki/Dobrynin_VD-4K

I have a few wonderful books, "TDevelopment of Piston Aero Engines" and "World Encyclopedia of Aero Engines", both by Bill Gunston. These explain the engine and one of them might even have a picture of it. I don't have access to my library at the moment, so the third source is my memory.

Off topic it is, could you pls forgive me...