Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

Explanation of how a320 CFM engine "works"

Wikiposts
Search
Tech Log The very best in practical technical discussion on the web

Explanation of how a320 CFM engine "works"

Thread Tools
 
Search this Thread
 
Old 8th Dec 2011, 08:21
  #1 (permalink)  
Thread Starter
 
Join Date: Apr 2011
Location: Canada
Age: 37
Posts: 96
Likes: 0
Received 0 Likes on 0 Posts
Explanation of how a320 CFM engine "works"

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.
z.khalid is offline  
Old 8th Dec 2011, 08:25
  #2 (permalink)  
 
Join Date: Sep 2010
Location: England
Posts: 1,955
Likes: 0
Received 0 Likes on 0 Posts
Suck, squeeze, bang, blow. Or...

The same way a Roller does.
Lord Spandex Masher is offline  
Old 8th Dec 2011, 08:29
  #3 (permalink)  
 
Join Date: Apr 2010
Location: London
Posts: 319
Likes: 0
Received 0 Likes on 0 Posts
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.
OutsideCAS is offline  
Old 8th Dec 2011, 09:57
  #4 (permalink)  
 
Join Date: Feb 2008
Location: Wingham NSW Australia
Age: 83
Posts: 1,343
Likes: 0
Received 0 Likes on 0 Posts
CFM Engine

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.
Old Fella is offline  
Old 8th Dec 2011, 12:32
  #5 (permalink)  
 
Join Date: Feb 2005
Location: flyover country USA
Age: 82
Posts: 4,579
Likes: 0
Received 0 Likes on 0 Posts
The engine has a fan. It keeps the pilots cool. If it stops, they start to perspire.
barit1 is offline  
Old 8th Dec 2011, 12:55
  #6 (permalink)  
 
Join Date: Mar 2002
Location: Florida
Posts: 4,569
Likes: 0
Received 1 Like on 1 Post
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
lomapaseo is offline  
Old 8th Dec 2011, 20:54
  #7 (permalink)  
 
Join Date: Sep 2010
Location: earth
Posts: 1,341
Likes: 0
Received 0 Likes on 0 Posts
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?
grounded27 is offline  
Old 8th Dec 2011, 21:02
  #8 (permalink)  
 
Join Date: Oct 2010
Location: Germany
Age: 47
Posts: 402
Likes: 0
Received 0 Likes on 0 Posts
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 !
aerobat77 is offline  
Old 8th Dec 2011, 21:52
  #9 (permalink)  
 
Join Date: Sep 2010
Location: earth
Posts: 1,341
Likes: 0
Received 0 Likes on 0 Posts
I am referring to the first spool as N1.
grounded27 is offline  
Old 8th Dec 2011, 22:21
  #10 (permalink)  
 
Join Date: Aug 2002
Location: Switzerland, Singapore
Posts: 1,309
Received 0 Likes on 0 Posts
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).
Dani is offline  
Old 10th Dec 2011, 04:02
  #11 (permalink)  
 
Join Date: Feb 1998
Location: Formerly of Nam
Posts: 1,595
Likes: 0
Received 0 Likes on 0 Posts
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?
Slasher is offline  
Old 10th Dec 2011, 04:54
  #12 (permalink)  
 
Join Date: Apr 2006
Location: Asia
Age: 49
Posts: 524
Likes: 0
Received 0 Likes on 0 Posts
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.
MD83FO is offline  
Old 10th Dec 2011, 14:47
  #13 (permalink)  
 
Join Date: Feb 1998
Location: Formerly of Nam
Posts: 1,595
Likes: 0
Received 0 Likes on 0 Posts
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.
Slasher is offline  
Old 10th Dec 2011, 14:51
  #14 (permalink)  
 
Join Date: Feb 2005
Location: flyover country USA
Age: 82
Posts: 4,579
Likes: 0
Received 0 Likes on 0 Posts
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 at the sort of inputs this guy is submitting.
barit1 is offline  
Old 10th Dec 2011, 18:25
  #15 (permalink)  
 
Join Date: Mar 2002
Location: Florida
Posts: 4,569
Likes: 0
Received 1 Like on 1 Post
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?
lomapaseo is offline  
Old 10th Dec 2011, 18:34
  #16 (permalink)  
Thread Starter
 
Join Date: Apr 2011
Location: Canada
Age: 37
Posts: 96
Likes: 0
Received 0 Likes on 0 Posts
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.
z.khalid is offline  
Old 10th Dec 2011, 19:32
  #17 (permalink)  
 
Join Date: Dec 2011
Location: Israel
Age: 27
Posts: 10
Likes: 0
Received 0 Likes on 0 Posts
I got the familiarization from this excellent guide:
Aircraft engine operation and malfunction
Avis1 is offline  
Old 14th Dec 2011, 02:37
  #18 (permalink)  
 
Join Date: Feb 2005
Location: flyover country USA
Age: 82
Posts: 4,579
Likes: 0
Received 0 Likes on 0 Posts
Have you seen this
barit1 is offline  
Old 14th Dec 2011, 04:57
  #19 (permalink)  
 
Join Date: Sep 2010
Location: earth
Posts: 1,341
Likes: 0
Received 0 Likes on 0 Posts
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.
WOW, Many words come to mind to describe this completely useless response. Just how is your time wasted lurking around the INTERNET Princess?
grounded27 is offline  
Old 14th Dec 2011, 22:30
  #20 (permalink)  
 
Join Date: Feb 1998
Location: Formerly of Nam
Posts: 1,595
Likes: 0
Received 0 Likes on 0 Posts
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?
Slasher is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.