Explanation of how a320 CFM engine "works"

[z.khalid]

I know about the components, the N1, N2, all the stages, but can somebody please explain to me how they would answer the question when asked
"Explain to me briefly how the CFM engine operates"?

How would you answer such a question?
Thank you.

[Lord Spandex Masher]

Suck, squeeze, bang, blow. Or...

The same way a Roller does.

[OutsideCAS]

Simple terms, it takes air in, compresses it, adds some fuel, ignites it, the resultant expansion of this gas then allows Newton's Third Law to become apparent as it leaves via the back and some of the energy is also tapped off for various other useful services along the length of the cycle. Crude answer, but brief.

[Old Fella]

Could be trite and simply say "Very efficiently" although I think the question may have been posed to determine if you know that it is a high bypass turbo fan engine where the majority of thrust is derived from the cold air stream. It might be just that simple an answer they are looking for.

[barit1]

The engine has a fan. It keeps the pilots cool. If it stops, they start to perspire.

[lomapaseo]

but can somebody please explain to me how they would answer the question when asked
"Explain to me briefly how the CFM engine operates"?



depends on who is asking the question and their level of knowledge

All the answers above are correct so pick and choose

I'll try another suitable for a wife or girl friend. :)

The engine has spinning blades inside it like a window fan or your hairdryer and these blades propel heated air out the back like a watering hose does with water. The jet propel out the back pushes the engine, hose etc. and what is attached to it.

You can probably get the same effect with your electric hairdryer by turning it to high and laying it down on the bathroom counter and watch it spin across the counter.

Please do not do this while taking a bath :E

[grounded27]

Engine has 2 spool's with each spool having turbine and compression sections..
Engine is brought up to minimum speed by a pneumatic motor attached to gearbox driving the 2nd spool.
Fuel is sprayed onto an ignition source between the compressor and turbine sections.
The acceleration of the 2nd spool creates more pressure between it and the first spool.
The first spool is connected to the fan that produces most of the thrust.
As you increase the fuel, pressure and airflow (thrust) are a result.

Really need to know what level of detail you are looking for but this is basically any dual spool turbine engine. Do you wish any more detail?

[aerobat77]

hi !

without much diskussing this topic just a small correction :

The first spool is connected to the fan that produces most of the thrust.

nope, the fan is connected to the "second spool" or more correctly the low pressure turbine. the "first spool" alias high pressure turbine drives the hp compressor.

but its correct that the fan produces most of the thrust.

best regards !

[grounded27]

I am referring to the first spool as N1.

[Dani]

CFM engine work like most other modern high-by-pass turbine jet engine. Why are you asking specifically about CFM? Are they wondering if there are differences? CFM is a company (more accurate a joint venture of some very big engine manufacturs).

[Slasher]

If I was asked the exact same question I'd give a exact same
answer as Lord S Masher gave (except I'd leave out the Rolly
Rip bit as the question asked "briefly").

BTW who is actually asking the question? An interview panel
for cadetship or the local drunk down the pub?

[MD83FO]

He is asking about a320 CFM why is that so difficult to answer. I fly the IAEs
I unsderstand CFMs start quicker because they can run hotter and are also more capable for hi elevation operations. The reveresers are also different.
Someone with CFM experience should be able to explain in more detail.

[Slasher]

Yeh but I can't be bloody bothered unless the poster states
succinctly WHAT he wants to know and the purpose of such
(like who's asking him the question) so that I don't waste my
time filling out reams of pages with explanations that may or
may not be useful to him.

[barit1]

The original question is so ambiguous, it has drawn a vast spectrum of answers, from the somewhat technical to the absurd.

If this is truly the nature of questions on today's exams - be they for certification or for employment - then I greatly fear for the future of our industry, for the inmates are running the asylum.

:*

BTW - Take a look (http://www.pprune.org/search.php?searchid=8241470) at the sort of inputs this guy is submitting. :eek:

[lomapaseo]

The original question is so ambiguous, it has drawn a vast spectrum of answers, from the somewhat technical to the absurd.


did you ever notice no mater how ambiguous the question is, we all try to answer it anyhow in order to demonstrate the depth of our knowlege.

That's the nature of the internet when you don't know the poster.

BTW did this guy ever respond bak with th answer that they were looking for, or were they just feeding?

[z.khalid]

Firstly, thank you all VERY much for the responses and help.
Much appreciated.

I was asked this question by my flight instructor and could not give back a proper answer.
I asked about the CFM specifically because we were talking about the airbus as that's the type rating i'm going to do soon, but now realize that it does not matter because any high bypass turbofan engine will basically operate in the same way.

I researched, and alot of answers were a little too detailed and I couldn't understand exactly how the engine worked still.

Thank you all once again, my apologies for being vague.

[Avis1]

I got the familiarization from this excellent guide:
Aircraft engine operation and malfunction (http://fromtheflightdeck.com/Stories/turbofan/)

[barit1]

Have you seen this video?

[grounded27]

Yeh but I can't be bloody bothered unless the poster states
succinctly WHAT he wants to know and the purpose of such
(like who's asking him the question) so that I don't waste my
time filling out reams of pages with explanations that may or
may not be useful to him.


WOW, Many words come to mind to describe this completely useless response. Just how is your time wasted lurking around the INTERNET Princess?

[Slasher]

WOW, Many words come to mind to describe this completely useless response.

I could say the same about yours spanky. Me, I expressed a
reason. You simply shot your silly bloody mouth off. So how
about you cough up some of those "many words" or write out
a burst of ten to fifteen paragraphs on the CFM (listing all the
FADEC differences would be useful to some) hmm?