Best approach for aero improvement on sedan roof? - Page 6 - Fuel Economy, Hypermiling, EcoModding News and Forum

aerohead · 08-31-2016, 07:02 PM

Quote:

Originally Posted by 19bonestock88

I figured I would restart this discussion, a member on here supplied me with some free individual vortex generators, and gave me a good idea to test the airflow without needing a chase car and photographer... He suggested to use flour sprinkled over the roof of the car and drive at low speed; there would be indicated attached flow where the flour was swept off, and that would show the point of separation, indicating to me where to place the vortex generators, giving the best possible result for the effort...

In addition to flour,NASA successfully used diatomacious earth for flow visualization.

19bonestock88 · 08-31-2016, 07:05 PM

Quote:

Originally Posted by aerohead

In addition to flour,NASA successfully used diatomacious earth for flow visualization.

So, in laymans terms, sand? Silt? Powdered clay?

aerohead · 08-31-2016, 07:25 PM

Quote:

Originally Posted by 19bonestock88

So, in laymans terms, sand? Silt? Powdered clay?

My introduction to it was with swimming pool water filtration in California.If we swam,we had to maintain to pool.
There is also a food grade diatomaceous earth (eaten for Calcium ).
It's finer than sand.It is very silty! Powdered clay might clump together,where the diatoms would just blow away.
It's available at pool supply and ACE Hardwares if you wanted to try it.
Hardwood fireplace ashes are great too!
Also,MIT's solar team took carbon black and kerosene and painted their racers with it to observe boundary layer airflow.(the original Corvette Sting Ray was analyzed this way at Cal Tech).

If the flour cakes together after sifting you'll have options.
Have fun!