Mercedes Power Unit Hardware & Software

[MrPotatoHead]

Here's a static (steady state) CFD simulation on a twin plenum V6 Intake Manifold that I did recently.
Hopefully this isn't off topic since it gives you an idea of the complexity of the flow and the velocities involved.
Velocity colours are shown on the top left.
You will notice differing velocity from the centre of the plenum to the edges as well.
https://i.imgur.com/wTzTkES.png

Nice image Mr P and a perfect illustration of our discussion. A couple of observations:
1. All the velocities are way too high. That doesn't matter much for the purposes of your sim but readers here should not take any notice of the actual values - perhaps divide them by 8 to 10.
2. The key take-away is the runner velocities are 2 - 3 times the plenum velocity. And of course most of the runner flow happens during about 1/4 of the cycle, so actual runner velocity is four times as high while the runner is flowing - and even higher at its peak.

So runner velocities at about 10x plenum velocity. This approaches the ideal of zero plenum velocity which is what you get with ITBs and open velocity stacks. (difficult on boosted motors)

The velocities are indeed too high because of the "open" nature of that simulation.
In this case the plenum inlets were at 3 bar (absolute) and the runner outlets were at 1 bar.
This was purely a pressure differential based simulation, which is how i do my static flow sim.

You are correct though - the plenum velocity will always be lower than the runner velocity - but, the velocity int he plenum can still be higher than you expect because of the dynamics of the engine.

Fun discussions - let's keep it up!

I should add though that I have not been involved in the intake side of any of the F1 engines, just some "other" parts with most of the teams.

[Tommy Cookers]

[quote=MrPotatoHead].......intake runner length tuning has less effect under forced induction.[/quote]
surely the scope of such tuning is the same regardless of whether NA or supercharged ?

the scope of exhaust length tuning is likely to be less when supercharged
ie unless we have an exhaust plenum box and a restrictor tailpipe

[digitalrurouni]

For Brazil do we know if they had full power from that PU for the entirety of the race? I am not counting qualifying mode.

[godlameroso]

.......intake runner length tuning has less effect under forced induction.

surely the scope of such tuning is the same regardless of whether NA or supercharged ?

the scope of exhaust length tuning is likely to be less when supercharged
ie unless we have an exhaust plenum box and a restrictor tailpipe

Isn't a turbine technically that?

[MrPotatoHead]

.......intake runner length tuning has less effect under forced induction.

surely the scope of such tuning is the same regardless of whether NA or supercharged ?

the scope of exhaust length tuning is likely to be less when supercharged
ie unless we have an exhaust plenum box and a restrictor tailpipe

I think it's partially because of the air density and the effect it has on intake tuning and response, but also because it's easier to get more power with forced induction in most cases people don't chase the devil in the details.

[PlatinumZealot]

I'm pretty sure that's solidworks CFD. I've had the misfortune of using it about 7-8 years ago.

Solidworks CFD depends on the skill of the user. You have to know its limitations... and yours.

[MrPotatoHead]

I'm pretty sure that's solidworks CFD. I've had the misfortune of using it about 7-8 years ago.

Solidworks CFD depends on the skill of the user. You have to know its limitations... and yours.

Absolutely. I'm still learning ways to do things with it all the time.

[63l8qrrfy6]

I'm pretty sure that's solidworks CFD. I've had the misfortune of using it about 7-8 years ago.

Solidworks CFD depends on the skill of the user. You have to know its limitations... and yours.

As opposed to all other CFD software that allow you to speak your request in a microphone and work it all out for you.

[3jawchuck]

I'm pretty sure that's solidworks CFD. I've had the misfortune of using it about 7-8 years ago.

Solidworks CFD depends on the skill of the user. You have to know its limitations... and yours.

Unlike most engineering tools.

[roon]

Here are the picture(s) that I remembered seeing of the intake plenums:

http://www.f1i.com/wp-content/uploads/2 ... ine_FR.jpg

http://www.f1i.com/magazine/magazine-te ... a-vjm09/3/

Is this the first example of a true equal-length intake manifold?

Look again at the pics hurrill has posted - there's a big ass rail running along the crank centreline with little wings extending on both sides towards the plenum. Want to hazard a guess what it does ?

I think it's a hydraulic actuator for the wastegate, detached amid disassembly. Held aloft by the rigidity of the hoses it's connected to. As for 'wings', I see only a flange extending toward one side.

As for VIM, if there is any such componentry within this manifold, it is not adding an appreciable amount of weight. Look how easily the mechanic wields the manifold with his one hand, gripping only the far end of the assembly.

There may be some interplay between the three intake tubes, each dropping in pressure relative to the others when its corresponding cylinder's intake valves are opening. The air within two intake tubes/runners, and the air within the plenum, would want to fill in the corresponding runner experiencing a drop in pressure. In such a context, is there only pressure drop, or does some back flow occur in the other runners? Maybe this is all within the domain of pulse wave tuning. I wonder how cylinder volume compares to runner volume.

[Sierra117]

For Brazil do we know if they had full power from that PU for the entirety of the race? I am not counting qualifying mode.

It's mentioned that it was full power throughout. Although from some of the videos, like the couple of onboards from Juz123, the engine mode dial seems to be in a couple different positions in some of the shots. I could be incorrectly interpreting though, since you're saying you're not counting q-mode, which means it's still full power (9-10 on the dial?). Toto also said that they gave Ham everything from the PU.

[toraabe]

Exactly. It also proves the advantage they have when it comes to outright power

[PlatinumZealot]

Ferrari were at full power as well. It was maybe enough power to stop the #44 car from an on track overtake after juncao, but I doubt they could have stopped a clean air undercut out of the pits.

[Sierra117]

Ferrari were at full power as well. It was maybe enough power to stop the #44 car from an on track overtake after juncao, but I doubt they could have stopped a clean air undercut out of the pits.

I'm a bit surprised that Ferrari being at full power is often left out of convos. They were, as you said, definitely on/at full beans. One can usually hear the difference in pitch and tone of the engine from onboards. Tbh I think Ham could pass given a few more laps, it was really just the dirty air that made it much harder.

[63l8qrrfy6]

I think it's a hydraulic actuator for the wastegate, detached amid disassembly. Held aloft by the rigidity of the hoses it's connected to. As for 'wings', I see only a flange extending toward one side.

I am pretty sure the wastegate actuator is the mechanism further back under that small cover. Can be seen clearer in the hypercar engine pics - it sits right on top of the turbine.