Here are my little CFD tests on the Mclaren MP4-27 exhaust as promised.
So on the car launch thread..
I thought the car was blowing the brake ducts..
I thought it was blowing the tyres..
I thought it was the beam wing..
I thought it was the diffuser...
Now here is the answer..at least what I think it's doing..
The Coanda effect is there.
IT is VERY SENSITIVE to air speed.
The coanda effect is stronger at low speeds and weaker at high speeds. In other words the exhuast plume bends down more at lower car speeds and is straighter at higher speeds.
My guess is that the faster free stream air tends to straighten out the exhaust at is more able to fill the low pressure pockets along the curvature of the car.
The exhaust is mostly deflected by down-wash and air coming in from the sides at higher speeds
IT is SENSITIVE to engine speed.
Being sensitive to so many factors, Mclaren Could be another Renault Front exit exhaust situation on their hands... Maybe Newey's beam wing blowing is much more consistent?
The exhaust blows under the brake duct.
As we should expect. I mean, why in the world would you want 800 degree celcius air blowing into your brakes that you are trying to cool coming down to that 5 g braking zone? hehe
It emerges beside the diffuser
corroborated by Mclaren's temperature stickers in the area.
Mclaren are effectively blowing the diffuser.
Kudos to those who guessed that the flow vis on the floor was being blown.
Pretty Picture results
This car I got from Ringo which originally came from Machin. I heavily bastardized it. I have my own F1 car model but it is not finished..hehe..
I had been through about 4 different tries to accurately match the position and things like the brake ducts etc.
I have data at two road speeds- 30m/s and 60m/s. Please, the geometry is not exactly the Mclaren but the trend is there. The velocity display I cut it too 100 m/s so you can see the pretty colours. Exhaust speed out of the pipe at 225 liter/second and 850C is about 348 m/s.
Sixty meters per second car speed ~134 mph
http://f1tcdn.net/images/forum/exhaust- ... -cfd/1.jpg
http://f1tcdn.net/images/forum/exhaust- ... -cfd/2.jpg
http://f1tcdn.net/images/forum/exhaust- ... -cfd/3.jpg
30 m/s car speed ~ 70 mph
bendind down more.
http://f1tcdn.net/images/forum/exhaust- ... -cfd/4.jpg
http://f1tcdn.net/images/forum/exhaust- ... -cfd/5.jpg
http://f1tcdn.net/images/forum/exhaust- ... -cfd/6.jpg
So there you have it. This is only my estimations!
"Raindrops .. drop top!"