xpensive wrote:When I find it rather obvious from the above pictures that exhausts are located on the sides, just ahead of the rear wheel
and below suspension parts, I find it difficult to see that this would aid the diffuser in any significant way?
A group working at Leafield (Super Aguri), I believe, discovered that channelling air from beneath the undertray could improve the performance of an F1 diffuser significantly. The idea was implemented most successfully in the Brawn vehicle last year, & gave the team a performance advantage over the first half of the season.
How does the "double diffuser" work? I'm not an aerodynamicist, & regard aerodynamics as a weird & wonderful black art, particularly so in complex & constrained regions to be found at the back of an F1 vehicle. For what it's worth, therefore, here are my thoughts:
1. Drawing additional air from beneath the undertray helps to reduce the mean pressure under the vehicle.
2. It will increase the mass flow of the upwash behind the vehicle.
3. It may help to keep the flow in the main diffuser "attached".
4. There was some talk of it helping to "connect" diffuser flow to rear wing flow, presumably implying that the whole becomes more than the sum of the parts, as it is in a well-designed bi-plane aircraft.
Now, how might a high energy exhaust stream help, augmented, as it is, by a mixing region immediately aft of the exhausts?
1. It appears to be directed at the trailing edge of the undertray, & that could help to improve air extraction from the undertray itself, thus lowering the pressure under the vehicle.
2. Some of the flow appears to be channelled into the diffuser region (look closely at one of the photographs posted above). This is where the Coanda effect might be relevant.
3. The increased mass flow through the diffuser complex (upper or lower, it matters not, I think) could amplify the "connection" between the diffuser & the rear wing (if that is relevant).
Much speculation from a layman, I know. The fact is, RBR have an observable performance advantage this year (probably more than Brawn had last year), & one obvious feature that is different is the position & direction of the exhaust flow. I have been hoping that aerodynamicists might help to clarify my rather un(in)formed ideas.