Turbofan

Stuff it. It's not my problem Yellowjacket used his complete ignorance of duct burning as his sole basis for saying there is no such thing because his ego couldn't accept the fact THE LITERATURE COMPLETELY SUPPORTS WHAT I SAID.

http://fliu.eng.uci.edu/Publications/J16.pdf

"In a conventional configuration (dashed line in Fig. 1) the HP,
high-temperature gas expands through the turbine, which provides
enough power to drive the compressor and fan and other engine
auxiliaries. To further increase the thrust level, fuel may be injected
and burned in the optional afterburner to increase further the temperature
of the gas before the flow expands through the nozzle to
produce the high-speed jet. For a turbofan engine part of the flow
that comes into the inlet is diverted to the fan bypass. The pressure
of the bypass flow is increased through the fan. The flow state after
the fan is marked as 03f . An optional duct burner behind the fan can
also be used to increase the thrust. The flow then expands through
the bypass nozzle into the atmosphere or mixes with the flow from
the core engine before expanding through a common nozzle."

 

As I wrote in the comment to the negative reps you've just got from me, I have reported your shameful posts to moderator. You are unworthy any minute one could spend on further arguing with you.

 

Shocker.

 

I am only responding to this because you are impuning my intregity and your lack of understanding on the subject has become annoying.

The above section and the bold quoted passage say nothing and do not relate to bypass ratio. They only say that burning in a bypass duct can produce an increase in thrust. All of that is true, but the resulting machine has to function and there are actual limits on how that machine functions that you clearly do not comprehend.

In order to mix the flows of the fan stream and the core stream they have to have the same total pressure. If you try to take too much energy out of the core stream to drive too large a fan, you cannot mix the flow streams. That in essence limts the range of bypass ratios that can be accomodated and the resulting engine configuration.

The above bold passage is defining an engine with the exhaust streams mixed and exiting from a common nozzle. As higher bypass ratios are obtained, it becomes impossible to mix the streams. Look at all of the very large high bypass engines and you will see a small separate exhaust nozzle for the core and a large nozzle forward on the engine for the fan stream. This is done because the total pressure in the fan stream is too different to mix with the core, and the engine will not work correctly with the streams mixed. There are some engines (like the RR 3007), that have a mixed core and fan stream, but these are not high bypass ratio engines, more like a "moderate" bypass ratio. But even in that engine, you can't effectively burn in the duct because the fan pressure ratio is only 1.7 to one, and you need a higher fan pressure ratio to employ a converging/diverging nozzle and create supersonic flow.

 

Finally, I took a couple of minutes to google Franklin Ratliff...

Here is what I found:

He is apparently not an engineer. He is employed at Lockheed Martin as a "Technical Writer".. Near as I can tell from that he is not an engineer, but makes his living writing reports for real engineers and perhaps he believes that he has absorbed a great amount of engineering acumen, perhaps by "osmosis"

He has had trouble on several other forums with his attitude and rude behavior.

http://www.landracing.com/forum/index.php?action=printpage;topic=4023.0

http://www.trackforum.com/forums/showthread.php?133376-Where-s-Franklin-Ratliff

http://www.freiburgersjunkyard.com/forum/showthread.php/2258-Franklin-Ratliff...

Apparently he has a fairly long history, going back at least 4 years of acting like he has in this thread...

As RedDwarf put it best,

Maybe if we just ignore him he will just go away.. Or at least we can hope.

 

GO

P
H
U
Q
U
E

YOURSELF.

 

"Maybe if we just ignore him he will just go away.. Or at least we can hope." If you believe that stupid
S
H
Y
T
E
then you're even more of an arrogant ignorant egotistical fool then you've already revealed yourself to be, if that's even humanly possible.

 

Nobody mentions bypass ratio, Sherlock, because a person has to be a fool not to understand it's PRESSURE RATIO not bypass ratio that matters in duct burning. Bypass ratio is simply the proportion of the airflow that goes through the fan instead of the core engine.

 

Please ignore. Quoted only for preservation, no hiding behind an edit after the meds kick in..

 

Quoting a message from one of the forums in the list:

"I hope Franky doesn't Google his name and end up here. He probably caused dozens of stress related deaths over at Nitronic a decade ago."
​

Looks like you have done a bad favor to those guys, by sharing these links...

 

Classic..

And BTW he's been involved in some other altercations on this board too..

http://www.boatdesign.net/forums/bo...faces-high-speed-cats-15642-2.html#post122968

Maybe if we get lucky the mod's will ban him.. Not like it hasn't happened to him before..

 

I'm still on Nitronic Research, Sherlock. Cole Coonce revived the group with a Facebook page.

 

Great, I'm happy for you. They evidently love you so much.

 

Pressure Ratio

The importance of FAN PRESSURE RATIO in turbofan engines as discussed in CURRENT turbofan research. LISTEN UP, Yellowjacket. Duct burning is possible because fans build PRESSURE, not just flow.

 

Me?..I'm just taking lots of notes and paying close attention. The concept of becoming a "subject matter expert" solely on the basis of some quick Google searches intrigues me no end. I think I may have to conclude that, up until this point in my career, I've been doing it wrong.

I will offer up the lame excuse that when I was heavily involved in gas turbine (and turbocharger) research working as a technician at Purdue's TSPC back in the early 80s..Google had not been thunk of yet.