Can some one please tell me a little bit about the colour of methane flames.

i think that lean flames burn blue? is this correct?

also how does the strain rate effect the colour of burning, i.e. from yellow to blue.

any points are welcome. thanks

Hi Paul, If I remember very well, I think that the coulour of flames depends on the spices which are present when methane burning. The blue coulor means that in that region the combustion is taking place in stoechiometric rates. The yellow coulor is due to soot emission and then indicates the presence of soot

and do you know anything about the way the colour may change as the flame becomes stetched and strained, i.e. close to extinction.

I've no idea, but you should know the spices which are present when the flame is turning off, and then you can deduce the colors. This can be done when you have the chemical schemes