Definition "lean out"
Join Date: Jun 2001
Location: Australia
Posts: 889
Likes: 0
Received 0 Likes
on
0 Posts
Is the 14.7 a total coincidence?
For example, consider using hydrogen (H2) as your fuel.
Two mols (a particular number of molecules) of hydrogen gas weighs about 4 grams. It will burn at the exactly correct mixture with one mol of oxygen.
One mol of oxygen gas weighs about 32 grams.
In this example, the "stoichiometrically correct mixture" for hydrogen burning with oxygen would by 4:32 or 1 (that should be "one : eight" - not a funny face!) by weight.
Avgas is a complex mix of different hydrocarbons, and air is a mix of (mainly) oxygen and nitrogen. If you get the exactly right number of mols of avgas and the exactly right number of mols of air, it will happen to work out at 14.7 to 1 weight to weight.
Cheers,
O8
Lean mixtures burn slower - hence greater heat produced & subsequent damage.
Added: its more that greater heat is retained due to prolonged burn vs time ti dissapate between combustion strokes.
Added: its more that greater heat is retained due to prolonged burn vs time ti dissapate between combustion strokes.