Engine related question

Rag

Hai everybody,

This is rag from Salmia university,Srilanka.I'm doing my P.hD in "diesel engines with spark plug for efficient combustion". my question is,

1.What is the limit of flame propagation of diesel fuel .i.e the ratio of air to fuel. For gasoline(petrol) it's around 6 to 22 parts of fuel to air.To be more specific 5 parts of air and 1 part of fuel won't burn.Likewise what is the limit for diesel.

2.How Combustion analysis using CFD can be done(i.e the methodology)