wwtad
Topic Author
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Joined: Wed Nov 29, 2017 2:00 pm

NOx emission of CFM LEAP

Wed Nov 29, 2017 2:36 pm

I had a look at the NOx emissions of the CFM LEAP-1A35 in the ICAO emission database and found very high values for take-off when compared to similar engines:
LEAP-1A35A: 54.13 g/kg fuel
LEAP-1A26: 18.77 g/kg fuel
PW1133G: 25.23 g/kg fuel
CFM56-5B3: 30.9 g/kg fuel

The LEAP-1A35A runs probably hotter than the other engines but does this alone explain the big difference?
Would that not lead to higher airport charges? Or are there no significant problems?
 
LH707330
Posts: 1784
Joined: Fri Jun 15, 2012 11:27 pm

Re: NOx emission of CFM LEAP

Wed Nov 29, 2017 4:21 pm

NOx output increases dramatically above a given temperature, so the LEAP's hot core in the highest-thrust version probably accounts for that spread. I'm not sure how their charges are calculated, but in the real world most takeoffs are done below max thrust, so the percentage of the time that the NOx output is that high is pretty low.
 
wwtad
Topic Author
Posts: 2
Joined: Wed Nov 29, 2017 2:00 pm

Re: NOx emission of CFM LEAP

Thu Nov 30, 2017 8:08 am

Ok, thank you for the explanation. I didn't expect it to rise so dramatically.
The highest rated version then is more similar to GEnx or GE90 than to its competitors.
GEnx-1B76A: 46.9
GE90-115B: 50.34
However, the climb out value (19.53 at 85% thrust) is lower and more similar to its competitors. Really a dramatic increase
 
LH707330
Posts: 1784
Joined: Fri Jun 15, 2012 11:27 pm

Re: NOx emission of CFM LEAP

Thu Nov 30, 2017 7:11 pm

Yeah, that seems plausible. There's some set of conditions (lean burn, temp > X) above which it drastically picks up, I'm sure Wikipedia knows more there.

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