Using this spoiler to reattach flow in high angle diffusers?

Here are our CFD links and discussions about aerodynamics, suspension, driver safety and tyres. Please stick to F1 on this forum.
g-force_addict
g-force_addict
0
Joined: 18 May 2011, 00:56

Using this spoiler to reattach flow in high angle diffusers?

Post

This one
Image
http://www.greencarcongress.com/2008/11 ... ler-d.html

Just placed upside down at the end of the diffuser.
Reportedly this helps channel boundary flow to better follow the body contours to reattach flow and reduce the trailing wake.

Could this spoiler be used in some other places?
Maybe as a bargeboard or as a flow conditioner?

CMSMJ1
CMSMJ1
Moderator
Joined: 25 Sep 2007, 10:51
Location: Chesterfield, United Kingdom

Re: Using this spoiler to reattach flow in high angle diffus

Post

Why don't you tell us? #-o
IMPERATOR REX ANGLORUM

thisisatest
thisisatest
18
Joined: 17 Oct 2010, 00:59

Re: Using this spoiler to reattach flow in high angle diffus

Post

isnt that thing for the top of the hatch of an suv or similar?
i can imagine that the spoiler is intended to mount on part of the body that normally absolutely separates from the boundary layer. mounted, the air is redirected somewhat smoothly, lowering drag. diffusers aren't designed to stall. if they were, you could use a spoiler like that, but then you're just back to where you were with a non-stalling diffuser. plus drag, weight, less downforce for a given structure volume.

ps- also, you wouldnt necessarily want to run this spoiler upside down as it is intended to reduce lift in its upright state.

g-force_addict
g-force_addict
0
Joined: 18 May 2011, 00:56

Re: Using this spoiler to reattach flow in high angle diffus

Post

Let's look at it upside down
Image

The inclined lower surface may well be a diffuser
After the diffuser the airflow will detach at the end of the car and form a large trailing wake
This is why the spoiler can reduce the trailing wake height by redirecting the flow upward.

User avatar
flynfrog
Moderator
Joined: 23 Mar 2006, 22:31

Re: Using this spoiler to reattach flow in high angle diffus

Post

Image

riff_raff
riff_raff
132
Joined: 24 Dec 2004, 10:18

Re: Using this spoiler to reattach flow in high angle diffus

Post

Wouldn't the profile of that spoiler device (as shown) locally produce lift? The diffuser boundary layer flow creates no net lift/downforce where it passes thru the constrained space between the diffuser surface and spoiler. And as the boundary flow passes over the unconstrained section of the spoiler profile, it would appear to produce an upward aero force.
"Q: How do you make a small fortune in racing?
A: Start with a large one!"

thisisatest
thisisatest
18
Joined: 17 Oct 2010, 00:59

Re: Using this spoiler to reattach flow in high angle diffus

Post

i was thinking about requiring something attached to the cars to recondition air for the following car. if the air is straightened out, there will be less downforce loss for the car behind, he can follow closer, there will be more passing, etc...
and then i thought about this doodad. does anyone think something like this could achieve that role? how would it be defined in rules? how... if a device smooths airflow from a downforce-generating wing or diffuser, does that automatically mean there is a loss of downforce?

olefud
olefud
79
Joined: 13 Mar 2011, 00:10
Location: Boulder, Colorado USA

Re: Using this spoiler to reattach flow in high angle diffus

Post

thisisatest wrote:i was thinking about requiring something attached to the cars to recondition air for the following car. if the air is straightened out, there will be less downforce loss for the car behind, he can follow closer, there will be more passing, etc...
and then i thought about this doodad. does anyone think something like this could achieve that role? how would it be defined in rules? how... if a device smooths airflow from a downforce-generating wing or diffuser, does that automatically mean there is a loss of downforce?
My original thought was that the device would diffuse the flow behind the subject vehicle but have little effect on the vehicle. As with the Kamm effect, the vehicle doesn’t know what’s happening to the slipstream once it passes the vehicle proper. But the thought of condition the slipstream for the benefit of following vehicles, while novel, could theoretically be of interest to rule writers –though this would open a new can of worms.