Well there might be a muffler hole and no muffler on the left.
a few adjustments to the model:
this is as close as it's gonna get for me. The pipe is 3.5 inch by 3 inch ellipse.
As can be seen with this floor is that the gases stay under. The pipe is above the step plane, so it's legal and the floor is shaped to as to keep everything down.
now the explanations; i'm not very good at doing these in an orderly fashion.
1. The diffuser blowing is much weaker than either redbull, mclaren or ferrari design. So it would not be of a real benefit to blow 3 miles away losing loads of energy to the ambient and crashish into the tyres, before the gases reaches the diffuser edge.
For this new floor i have here. The gases do not stay under the floor at all. They don't curl over it either.
That wasn't the case before on the model due to the floor shape and the splitter shape, but if Renault team spent time tuning and testing, then it even harder for anyone else to mimic.
After now having the proper features it can be safe to say the bulge in the floor makes it even more difficult for the gases to go back under or even curl over the top like we observed in the first model.
Concerning the exhaust energy. It loses much temperature by the time it reaches the diffuser and most of this energy is absorbed away from the floor, so does little to benefit the diffuser directly.
It's basic understanding that the redbull design will have much more energy going between the wheels and diffuser.
So if the R31 exhaust isn't as effective at blowing the diffuser, why go through the trouble of implementing it?
2. Blowing else where accomplishes more things that simply wafting gas to the diffuser. more on these other things later.
This^...
we need to forget about the diffuser for a moment, there are more places on the car just as important.
The r31 pipes are targeted at 3 performance parameters, the floor size, the splitter suction and the 4 tyres.
The former parameters targeting downforce and the later drag; the tyres being one of the main sources of drag on an F1 car.
If we look on a wake pattern from a car without the FEE it will look like this:
Notice what the wheels are doing?
The wheels create a lot of drag becuase of the huge wake they leave behind. Not only do the create drag but they negatively impacts the floor with the turbulent and poor flowing air comin off them. Especially the front of the rear wheel.
Now enter the FEE car.
FEE above, non FEE below.
See that blue area circled by the black ring on the non FEE? The FEE is now blowing that area and it's green (faster). So it's keeping the velocity high near the edge of the floor and preventing circulation that usually takes place there on most flat bottom cars.
Higher speeds and energy in the wake, less drag.
The wake of the car is also narrowed, look on the black line beside the front tyre, and also look at the redder colours in front the rear wheel.
All of this reduces drag and is thanks a type of wake control by the exhaust. Should help the R31 on the straights.
Now for the downforce part. The pink line is indicating where there is high velocity under the floor; the yellow and green boundary.
Notice how wider the yellow area is with the FEE above. It goes beyond the floor!
The floor is seeing a much higher flow rate and it's effectively a good 150 mm wider.
Compare the red areas under the splitter and front of the floor as well. The FEE is siphoning and pulling more suction at the front so the down-force gain is nearer the centre of the car.
In summary these gains cannot be achieved if the gases stay under the floor. The r31 cannot have an effectively bigger floor if the gases don't venture out and act as a skirt.
3. Renault creates down force else where which has a propagating effect that more effectively improves the diffuser.
Focusing on the diffuser alone wouldn't be wise, since other teams have much stronger and focused flows going there.
The FEE simply creates downforce else where. It does it in totalitity by creating more suction at the front of the car in the splitter are and more suction at the floor.
All these in turn will benefit the diffuser downstream as well, so the diffuser isn't being ignored, it's just not the only thing to be considered.
The pressure plot above speaks for itself. Notice the dark blue areas and how much bigger they are on the FEE car.
All of that is downforce smack dab in the middle of the car, which help in a very good balance.
This is mainly possible by blowing outwardly and creating a skirt effectively increasing floor size.
