Alfa Romeo C42

[Nimrod]

Nope! I love the way that Sauber does its own thing. This roll hoop obviously works for them.
Looking forward to the launch & then seeing how this interesting design compares to the rest of the field.

[godlameroso]

https://ibb.co/L68HPJD

Are these the ventury strakes running all the way into the floor edge?

Interesting to see a similar cooling/undercut philosophy to Aston Martin with no visible heat outlet at the rear and the use of the Venetian sidepod. Everything looks just a bit rounder and less "extreme" than on the green car.

Interesting how the leading edge of the main side strake for the ventury tunnel is very rounded at the tip, so far the other two real cars show really a sharp edge there.

How teams manage the bump from the lower SIP is going to be interesting, jelly mold it or run a smoother cover over it? All of these things are really nice to see, lots of technical diversity!

Thanks for pointing that out! Those ducts are worth a lot of performance, that's the first hint of what teams are planning to do with them. Getting those strakes just right or catastrophically wrong can be worth 100 points of downforce.

https://www.thomaswarren-portfolio.com/work/f12022



Look at the pressure distribution after the strakes on these two designs. The one on top had 60 points of downforce more than the bottom design, and that's with a beyond basic floor.



Looking at your image and the one above I don't know if the strakes can go that far back though.

[Mansell89]

Does anyone know if that was the new Ferrari PU in the back of the Alfa in the shakedown?

[godlameroso]

Does anyone know if that was the new Ferrari PU in the back of the Alfa in the shakedown?

Yes it was the new power unit.

[Mansell89]

Does anyone know if that was the new Ferrari PU in the back of the Alfa in the shakedown?

Yes it was the new power unit.

Thanks man- hopefully reliable out the box and of course, competitive

[adrianjordan]

I think the track Mic's are probably tuned to a smaller spectrum of sound in an effort to isolate the car and leave out the ambient noises from crowds etc?

You can probably get away with what the phone is doing at an empty Fiorano but if there was a big crowd there and 20 other cars, maybe we wouldn't enjoy 1 car's sound in isolation?

They have mics on the cars though as well. I only have a passable knowledge of sound production, but I know enough to know that they could do a better job of getting the sound of the cars across if they set their minds to it.

[Pandamasque]

I think the track Mic's are probably tuned to a smaller spectrum of sound in an effort to isolate the car and leave out the ambient noises from crowds etc?

You can probably get away with what the phone is doing at an empty Fiorano but if there was a big crowd there and 20 other cars, maybe we wouldn't enjoy 1 car's sound in isolation?

They have mics on the cars though as well. I only have a passable knowledge of sound production, but I know enough to know that they could do a better job of getting the sound of the cars across if they set their minds to it.

The mics on the cars are only used for onboard shots. Otherwise the broadcast would sound extremely weird. Also, mics on the cars capture a very different "picture". Race car sound as we know it is a product of exhaust sound reverberating within an environment, which you don't get from onboard mics due to proximity. Take the ambience away and you end up with something that sounds like an old video game. With a handful of cars on track captured by a phone mic you get a lot more of the ambience than a TV broadcast can afford. On top of that phones compress sound a lot (i.e. quieter sounds are brought up in level). I assume the levels of track mics for broadcasts are set up to cope with an entire field of cars passing at once, that means they're fairly low and miss out on a lot of the ambiance. It's not just with these turbocharged V6s. Pretty much any race car testing on its own captured on a decent smartphone will sound more impressive than in a broadcast.

I'm not saying there's no room for improvement.

[dren]

https://ibb.co/L68HPJD

Are these the ventury strakes running all the way into the floor edge?

Interesting to see a similar cooling/undercut philosophy to Aston Martin with no visible heat outlet at the rear and the use of the Venetian sidepod. Everything looks just a bit rounder and less "extreme" than on the green car.

Interesting how the leading edge of the main side strake for the ventury tunnel is very rounded at the tip, so far the other two real cars show really a sharp edge there.

How teams manage the bump from the lower SIP is going to be interesting, jelly mold it or run a smoother cover over it? All of these things are really nice to see, lots of technical diversity!

Thanks for pointing that out! Those ducts are worth a lot of performance, that's the first hint of what teams are planning to do with them. Getting those strakes just right or catastrophically wrong can be worth 100 points of downforce.

https://www.thomaswarren-portfolio.com/work/f12022

https://images.squarespace-cdn.com/cont ... 022+F1.png

Look at the pressure distribution after the strakes on these two designs. The one on top had 60 points of downforce more than the bottom design, and that's with a beyond basic floor.

https://i.ibb.co/pZx5PR6/strakes-6-DFm-AHs.jpg

Looking at your image and the one above I don't know if the strakes can go that far back though.

It appears the bottom design has more low pressure between the inner strake and the tub than the upper one. Since teams have computers that do this work for them and have lots of previous experience, I highly doubt they will get this catastrophically wrong.

[godlameroso]

The bottom one was choking, the inner strake and the plank area accelerated the flow too much and the vortex broke down before the diffuser kick. The mass flow was much higher on the top design. The main acceleration of flow should be at the venturi throat. By having the strake so close to the body you create a big pressure differential at the inlet and throat that forms between them. IE choked flow. The strakes are ducts just as much as they are flow conditioners. Converging ducts accelerate air, diverging ducts slow it down and increase pressure. When converging ducts see a big enough pressure difference between the inlet and throat, the flow becomes choked, the speed is sonic and in a sonic regime flow slows down when converges and accelerates when it diverges. The bottom design is a perfect example of converging till choking, the sharp low pressure shows that upstream flow is choked. There is a clear normal shock.



Here is an example of choked flow.

[adrianjordan]

I think the track Mic's are probably tuned to a smaller spectrum of sound in an effort to isolate the car and leave out the ambient noises from crowds etc?

You can probably get away with what the phone is doing at an empty Fiorano but if there was a big crowd there and 20 other cars, maybe we wouldn't enjoy 1 car's sound in isolation?

They have mics on the cars though as well. I only have a passable knowledge of sound production, but I know enough to know that they could do a better job of getting the sound of the cars across if they set their minds to it.

The mics on the cars are only used for onboard shots. Otherwise the broadcast would sound extremely weird. Also, mics on the cars capture a very different "picture". Race car sound as we know it is a product of exhaust sound reverberating within an environment, which you don't get from onboard mics due to proximity. Take the ambience away and you end up with something that sounds like an old video game. With a handful of cars on track captured by a phone mic you get a lot more of the ambience than a TV broadcast can afford. On top of that phones compress sound a lot (i.e. quieter sounds are brought up in level). I assume the levels of track mics for broadcasts are set up to cope with an entire field of cars passing at once, that means they're fairly low and miss out on a lot of the ambiance. It's not just with these turbocharged V6s. Pretty much any race car testing on its own captured on a decent smartphone will sound more impressive than in a broadcast.

I'm not saying there's no room for improvement.

Yes, but at the moment they're doing a piss poor job and could definitely do better. Multiple mic locations on the car to give a better mix of sounds. Directional track side mics to cut out crowd noise while focusing more on the cars.

In terms of compression etc, that is nothing that a basic piece of sound production software can't do in real time.

They could do a much, much better job that they currently do. They just don't appear to have any desire to do so.

[Zynerji]

A pressure transducer installed into an O2 bung post-turbo could give a clean signal for audio.

[theVortexCreatorY250]

The bottom one was choking, the inner strake and the plank area accelerated the flow too much and the vortex broke down before the diffuser kick. The mass flow was much higher on the top design. The main acceleration of flow should be at the venturi throat. By having the strake so close to the body you create a big pressure differential at the inlet and throat that forms between them. IE choked flow. The strakes are ducts just as much as they are flow conditioners. Converging ducts accelerate air, diverging ducts slow it down and increase pressure. When converging ducts see a big enough pressure difference between the inlet and throat, the flow becomes choked, the speed is sonic and in a sonic regime flow slows down when converges and accelerates when it diverges. The bottom design is a perfect example of converging till choking, the sharp low pressure shows that upstream flow is choked. There is a clear normal shock.



Here is an example of choked flow.

The bottom one was not choking. Althought the vortex breaks down eariler the extra downforce is evident.

[godlameroso]

The bottom one was choking, the inner strake and the plank area accelerated the flow too much and the vortex broke down before the diffuser kick. The mass flow was much higher on the top design. The main acceleration of flow should be at the venturi throat. By having the strake so close to the body you create a big pressure differential at the inlet and throat that forms between them. IE choked flow. The strakes are ducts just as much as they are flow conditioners. Converging ducts accelerate air, diverging ducts slow it down and increase pressure. When converging ducts see a big enough pressure difference between the inlet and throat, the flow becomes choked, the speed is sonic and in a sonic regime flow slows down when converges and accelerates when it diverges. The bottom design is a perfect example of converging till choking, the sharp low pressure shows that upstream flow is choked. There is a clear normal shock.



Here is an example of choked flow.

The bottom one was not choking. Althought the vortex breaks down eariler the extra downforce is evident.

I can demonstrate that it was. In regular air, flow will choke in a duct if the inlet pressure is twice the pressure in the throat. The leading edge of the floor is the inlet, notice the sharp high pressure on the outboard of the strakes. You notice the pressure differential is much lower on the top design vs the bottom one. The strakes and the center car body form a duct, the strakes raise the pressure outboard with their outwash, and create a pressure difference at the inner strake and center car body. Notice the red and the transition to blue, to me a 2:1 pressure ratio is evident. Choked flow doesn't mean no flow, it means no more upstream flow than what has been achieved. Choked flow is sonic flow and thus follows compressible flow rules. As the strakes diverge the speed increases, but the vortex breaks down before it can be accelerated by the venturi tunnel, because the mass flow is limited.

The top design has more mass flow and although choking still happens, the shockwave and expansion fan is more mild as you can see by the weaker vortex.



Choking at the inlet is not desirable, choking at the throat of the venturi tunnel is, because as the top design shows, if the pressure in the diffuser is choked, then it will pull in air by the edge wing. You'll notice the pressure trace at the edge wing and the beam wing is higher than the bottom one. To me, that indicates higher mass flow, and lower pressure overall.

Downforce with these rules depends on thrusting the air under the car, well thrust = mass flow x velocity. Downvote away.

[theVortexCreatorY250]

The bottom one was choking, the inner strake and the plank area accelerated the flow too much and the vortex broke down before the diffuser kick. The mass flow was much higher on the top design. The main acceleration of flow should be at the venturi throat. By having the strake so close to the body you create a big pressure differential at the inlet and throat that forms between them. IE choked flow. The strakes are ducts just as much as they are flow conditioners. Converging ducts accelerate air, diverging ducts slow it down and increase pressure. When converging ducts see a big enough pressure difference between the inlet and throat, the flow becomes choked, the speed is sonic and in a sonic regime flow slows down when converges and accelerates when it diverges. The bottom design is a perfect example of converging till choking, the sharp low pressure shows that upstream flow is choked. There is a clear normal shock.



Here is an example of choked flow.

The bottom one was not choking. Althought the vortex breaks down eariler the extra downforce is evident.

I can demonstrate that it was. In regular air, flow will choke in a duct if the inlet pressure is twice the pressure in the throat. The leading edge of the floor is the inlet, notice the sharp high pressure on the outboard of the strakes. You notice the pressure differential is much lower on the top design vs the bottom one. The strakes and the center car body form a duct, the strakes raise the pressure outboard with their outwash, and create a pressure difference at the inner strake and center car body. Notice the red and the transition to blue, to me a 2:1 pressure ratio is evident. Choked flow doesn't mean no flow, it means no more upstream flow than what has been achieved. Choked flow is sonic flow and thus follows compressible flow rules. As the strakes diverge the speed increases, but the vortex breaks down before it can be accelerated by the venturi tunnel, because the mass flow is limited.

The top design has more mass flow and although choking still happens, the shockwave and expansion fan is more mild as you can see by the weaker vortex.

https://images.squarespace-cdn.com/cont ... 022+F1.png

Choking at the inlet is not desirable, choking at the throat of the venturi tunnel is, because as the top design shows, if the pressure in the diffuser is choked, then it will pull in air by the edge wing. You'll notice the pressure trace at the edge wing and the beam wing is higher than the bottom one. To me, that indicates higher mass flow, and lower pressure overall.

Downforce with these rules depends on thrusting the air under the car, well thrust = mass flow x velocity. Downvote away.

I don't understand why your going to choke at 2:1, do you have a reference? I wouldn't be surprised if the teams achieve well over 3:1.
How can you comment on this without a colour scale?
I highly doubt this CFD is density based,thus compressibility effects are neglected. Yes the bottom vortex breaks down eariler, but it still creates WAY more downforce.

[godlameroso]

The bottom one was not choking. Althought the vortex breaks down eariler the extra downforce is evident.

I can demonstrate that it was. In regular air, flow will choke in a duct if the inlet pressure is twice the pressure in the throat. The leading edge of the floor is the inlet, notice the sharp high pressure on the outboard of the strakes. You notice the pressure differential is much lower on the top design vs the bottom one. The strakes and the center car body form a duct, the strakes raise the pressure outboard with their outwash, and create a pressure difference at the inner strake and center car body. Notice the red and the transition to blue, to me a 2:1 pressure ratio is evident. Choked flow doesn't mean no flow, it means no more upstream flow than what has been achieved. Choked flow is sonic flow and thus follows compressible flow rules. As the strakes diverge the speed increases, but the vortex breaks down before it can be accelerated by the venturi tunnel, because the mass flow is limited.

The top design has more mass flow and although choking still happens, the shockwave and expansion fan is more mild as you can see by the weaker vortex.

https://images.squarespace-cdn.com/cont ... 022+F1.png

Choking at the inlet is not desirable, choking at the throat of the venturi tunnel is, because as the top design shows, if the pressure in the diffuser is choked, then it will pull in air by the edge wing. You'll notice the pressure trace at the edge wing and the beam wing is higher than the bottom one. To me, that indicates higher mass flow, and lower pressure overall.

Downforce with these rules depends on thrusting the air under the car, well thrust = mass flow x velocity. Downvote away.

I don't understand why your going to choke at 2:1, do you have a reference? I wouldn't be surprised if the teams achieve well over 3:1.
How can you comment on this without a colour scale?
I highly doubt this CFD is density based,thus compressibility effects are neglected. Yes the bottom vortex breaks down eariler, but it still creates WAY more downforce.

P0 is reservoir pressure, in our case the inlet, and Pc is pressure measured at the throat.

Bottom floor actually is down 60 points of downforce vs the top one. Furtheremore, I have a lot of experience with choked flow in a duct, the artifacts are obvious and clear. Once again, I refer you to that youtube video I posted, you see the same choked flow phenomena.