Quote:
Originally Posted by 88'rolla
Hello, Ive been a long time lurker here on this board - a search usually finds the information I'm interested in, so I haven't ever really needed to post.
I am trying to derive a simple (read: very simple - no Crr, Δm, a, etc.) mathematical model for the rate of fuel consumption with regards to air resistance only, assuming constant V and m.
So far I've gotten:
B=(BSFC/ρη)Fd
Where η, efficiency, Fd, drag force, and ρ, energy density, are known.
η=1/(BSFC*ρ) => BSFC=1/(η*ρ)
B=fuel consumption (which I'm ultimately trying to find in gal/100mi).
I figure this would be the correct thread. Am I on the right track? If not, any insight would be great.
Thanks, and nice to finally meet everyone!
|
If you have a baseline mpg at a steady 55-mph,or 70-mph,and have made changes which affect only the drag coefficient,then the following relationships developed by General Motors, may be used with a high degree of confidence:
*A 10% drag reduction @ 55-mph will yield a 5% increase in mpg .
*A 10% drag reduction @ 70-mph will yield a 6% increase.
From here.you can convert into any useful unit of measure.
The relationship presumes a constant BSFC,and it has been reported by others that proper gear-matching is necessary to derive the full benefit of the drag reduction,but thermodynamically,the percentages are correct.