F1 Evaluating ‘Wheel Arches’

[Farnborough]

So everyone is in agreement that the water flowing up centrally, very high behind the rear wing, is flow effectively from the tyres?

Does this not seem like a lot of flow affected by the tyre, which teams desperately try to avoid with complex flow structures underneath the car, and as much outwash as possible?

A valid point in my view. I noted on RB 19 thread the effect of outwash under different circumstances at Zandvoort race. Loosely, as floor started working the outwash plume was huge, then as MV hit the brakes (first few laps of track saturation after race restarting) the outwash plume all but dissappeard as rear of chassis elevated under brake load, virtually switch like as it established and decayed with chassis plane orientation, not much tyre difference speed wise at that switch point.

Worthwhile watching replay to observe how dramatic it is.

[mzso]

We will evaluate the 'mudguards', systems, which can limit the spray phenomenon,” he added. “But we are also evaluating the possibility of intervening on the diffuser outlet.

“It is an important issue

There's no particular solution at the moment. But, as you saw in F1, there was the first learning step towards some solutions.

“I know there was a bit of criticism, and I read it was a failure, but in any of these situations, you've got to try things. And that's exactly what we did.

“It certainly wasn't a failure, because we learned a lot from it. And the next iterations will get better and better.”

https://www.autosport.com/f1/news/f1-ey ... /10514198/

Another stillborn idea. So what? They're going to place a giant plate on the inner side of the wheel? Not going to happen...

[organic]

More info about upcoming tests

It seems like the first test was a minimal approach which would not have had a big effect on aero performance, but it obviously did not work.

https://www.motorsport.com/f1/news/fia- ... /10519618/

The FIA’s single seater director Nikolas Tombazis has explained that, following analysis of what happened at Silverstone, the next test will be with a much different design.

“What was done at Silverstone, with the help of Mercedes who created parts and McLaren [who ran a car to get feedback on spray] was perhaps too optimistic an experiment,” Tombazis told Motorsport.com

“The spray guards covered too little of the wheel. I was quite sceptical and imagined that we wouldn't see important results.

“In the next tests we will carry out, we will test complete coverage of the wheel, going even beyond what would be needed to understand what the threshold is at which the spray forms. Then we will decide which path to take.”

Tombazis has explained just how complicated finding a solution is, with the excessive spray thrown up by F1 cars being triggered by different factors.

“The first is from the water that is extracted from the tyres and shot upwards,” he said. “A second effect derives from the accumulation of water between the wheel and the asphalt in the tyre squirt area (between the wheel and floor edge), which is sucked into the diffuser.

“The third effect is given by the water that stagnates in the cracks in the ground and, under the pressure of the diffuser, is sucked up and expelled.”

He added: “We believe that the spray coming from the wheels corresponds to approximately 40% of the total.

“If we were able to limit this phenomenon, it is clear that the drivers would not have complete visibility, but there would be a significant improvement.”

Tombazis says the FIA has been looking at tools used by the road car industry to simulate wet weather conditions when it comes to ensuring safety.

“We have done some simulations and there are tools that are often used in the production car industry (for example checking visibility for rear view mirrors), but these tools must be calibrated well to have a good correlation.

“The car manufacturers carry out very extensive calibration and, as they do not have testing restrictions and do not have to deal with an FIA which imposes constraints, they can act freely.

“We do not have the possibility to carry out frequent tests, so with limited activities it is not easy to find the right calibrations.”

One of the issues at play with a bigger wheel covering is aerodynamics, as it will have a much bigger impact on airflow than the original test versions.

“The [downforce] deterioration can vary greatly,” he said. “In some configurations we tried it was almost zero, while in the most extreme solutions we tested in a tunnel we saw a loss of up to 80 points, which can be worth two or three seconds in lap time.

“But honestly, we don't really care about the performance threshold, although the teams are definitely watching it. In the Silverstone test, the solution tested had the lowest possible aerodynamic impact."

[vorticism]

+1 organic* Given that 60% (per claim) of the spray comes from the floor aero, it might be worth considering blocking off the diffuser. Huge DF loss but greater reduction in spray and no wheel guards needed, and you still keep FW and RW DF. One simple part to install/remove: a blocking panel hanging from the crash structure. Or do both and have almost zero spray. Would slower cars and no spray be better than fast cars with spray? During rain.

*(I'd upvote but hollus switched off my voting)

[mzso]

+1 organic* Given that 60% (per claim) of the spray comes from the floor aero, it might be worth considering blocking off the diffuser. Huge DF loss but greater reduction in spray and no wheel guards needed, and you still keep FW and RW DF. One simple part to install/remove: a blocking panel hanging from the crash structure. Or do both and have almost zero spray. Would slower cars and no spray be better than fast cars with spray? During rain.

*(I'd upvote but hollus switched off my voting)

No such thing was claimed. As a matter of fact the diffuser was mentioned lastly.
The second thing he mentioned was this: "A second effect derives from the accumulation of water between the wheel and the asphalt in the tyre squirt area."
Whatever this means...

[vorticism]

No such thing was claimed. As a matter of fact the diffuser was mentioned lastly.
The second thing he mentioned was this: "A second effect derives from the accumulation of water between the wheel and the asphalt in the tyre squirt area."
Whatever this means...

It's all in the post above mine. 40% from the tyres ("first" effect), the rest i.e. presumably 60% based on wording ("second" and "third" effects) are from tyre squirt and diffuser pull i.e. the floor generally. What drives the floor? Le diffuser. No flow through diffuser and intensity of tyre squirt and other floor phenomena will reduce. Only thing left proximal to the road is the FW which, as not mentioned, must contribute a trivial amount of spray.

[mzso]

No such thing was claimed. As a matter of fact the diffuser was mentioned lastly.
The second thing he mentioned was this: "A second effect derives from the accumulation of water between the wheel and the asphalt in the tyre squirt area."
Whatever this means...

It's all in the post above mine. 40% from the tyres ("first" effect), the rest i.e. presumably 60% based on wording ("second" and "third" effects) are from tyre squirt and diffuser pull i.e. the floor generally. What drives the floor? Le diffuser. No flow through diffuser and intensity of tyre squirt and other floor phenomena will reduce. Only thing left proximal to the road is the FW which, as not mentioned, must contribute a trivial amount of spray.

"accumulation of water between the wheel and the asphalt" does not mean diffuser. Diffuser was mentioned last and least, so definitely not 60%. Might be 10 percent. Or nothing, I have doubts about FIA's capabilities.

[vorticism]

"accumulation of water between the wheel and the asphalt" does not mean diffuser. Diffuser was mentioned last and least, so definitely not 60%. Might be 10 percent. Or nothing, I have doubts about FIA's capabilities.

The grammatical syntax order of the wording is irrelevant in this context. Tyre squirt does imply the diffuser for the reason stated, please try to understand the post before rushing to point out perceived logical faults. You also have to consider that it's going to be parts close to the ground which are most at cause. That leaves two part groups: the floor (which include the diffuser as an integral part) and the tyres. We might throw out the FW as trivial contributor based on the wording of the article and our own logic. That leaves the monocoque/engine cover, suspension arms, and RW as remaining component groups, none of which are close to the ground. As such these would also be trivial contributors to the remaining 60% after the presumed accurate claim of 40% from the tyres.

[Just_a_fan]

No such thing was claimed. As a matter of fact the diffuser was mentioned lastly.
The second thing he mentioned was this: "A second effect derives from the accumulation of water between the wheel and the asphalt in the tyre squirt area."
Whatever this means...

It's all in the post above mine. 40% from the tyres ("first" effect), the rest i.e. presumably 60% based on wording ("second" and "third" effects) are from tyre squirt and diffuser pull i.e. the floor generally. What drives the floor? Le diffuser. No flow through diffuser and intensity of tyre squirt and other floor phenomena will reduce. Only thing left proximal to the road is the FW which, as not mentioned, must contribute a trivial amount of spray.

40% thrown up in the air by the tyres, the rest split between a) water thrown sideways by the tyre (the tyre squirt) which is picked up by the diffuser flow and b) pressure in the diffuser throat. The a) bit will be a much bigger effect than the b) bit - the tyres expel tens of litres of water per second and almost all of that water is being thrown in to the air firstly by the tyre's face itself and the rest by the aerodynamics at the rear of the car. The diffuser isn't sucking up huge amounts of water.

The proof? Just look at how the dry line develops. It starts as a pair of lines where the tyres are, it doesn't start as a car-wide strip.

[mzso]

"accumulation of water between the wheel and the asphalt" does not mean diffuser. Diffuser was mentioned last and least, so definitely not 60%. Might be 10 percent. Or nothing, I have doubts about FIA's capabilities.

The grammatical syntax order of the wording is irrelevant in this context. Tyre squirt does imply the diffuser for the reason stated, please try to understand the post before rushing to point out perceived logical faults. You also have to consider that it's going to be parts close to the ground which are most at cause. That leaves two part groups: the floor (which include the diffuser as an integral part) and the tyres. We might throw out the FW as trivial contributor based on the wording of the article and our own logic. That leaves the monocoque/engine cover, suspension arms, and RW as remaining component groups, none of which are close to the ground. As such these would also be trivial contributors to the remaining 60% after the presumed accurate claim of 40% from the tyres.

No it's not, that's not how humans work. And if you prevent tire squirt the diffuser won't do anything with it. Plus with or without the diffuser there'll always be some upwards airflow.

[Big Tea]

No such thing was claimed. As a matter of fact the diffuser was mentioned lastly.
The second thing he mentioned was this: "A second effect derives from the accumulation of water between the wheel and the asphalt in the tyre squirt area."
Whatever this means...

It's all in the post above mine. 40% from the tyres ("first" effect), the rest i.e. presumably 60% based on wording ("second" and "third" effects) are from tyre squirt and diffuser pull i.e. the floor generally. What drives the floor? Le diffuser. No flow through diffuser and intensity of tyre squirt and other floor phenomena will reduce. Only thing left proximal to the road is the FW which, as not mentioned, must contribute a trivial amount of spray.

40% thrown up in the air by the tyres, the rest split between a) water thrown sideways by the tyre (the tyre squirt) which is picked up by the diffuser flow and b) pressure in the diffuser throat. The a) bit will be a much bigger effect than the b) bit - the tyres expel tens of litres of water per second and almost all of that water is being thrown in to the air firstly by the tyre's face itself and the rest by the aerodynamics at the rear of the car. The diffuser isn't sucking up huge amounts of water.

The proof? Just look at how the dry line develops. It starts as a pair of lines where the tyres are, it doesn't start as a car-wide strip.

Would that not be due to the tyres being hot?

[Just_a_fan]

It's all in the post above mine. 40% from the tyres ("first" effect), the rest i.e. presumably 60% based on wording ("second" and "third" effects) are from tyre squirt and diffuser pull i.e. the floor generally. What drives the floor? Le diffuser. No flow through diffuser and intensity of tyre squirt and other floor phenomena will reduce. Only thing left proximal to the road is the FW which, as not mentioned, must contribute a trivial amount of spray.

40% thrown up in the air by the tyres, the rest split between a) water thrown sideways by the tyre (the tyre squirt) which is picked up by the diffuser flow and b) pressure in the diffuser throat. The a) bit will be a much bigger effect than the b) bit - the tyres expel tens of litres of water per second and almost all of that water is being thrown in to the air firstly by the tyre's face itself and the rest by the aerodynamics at the rear of the car. The diffuser isn't sucking up huge amounts of water.

The proof? Just look at how the dry line develops. It starts as a pair of lines where the tyres are, it doesn't start as a car-wide strip.

Would that not be due to the tyres being hot?

No, it's due to the tyres dispersing water. It happens on road cars too and their tyres are cold, especially in wet weather.

[Just_a_fan]

Plus with or without the diffuser there'll always be some upwards airflow.

Exactly so - road cars create spray too and they don't even try to lift their wake high in to the air. A busy road in the rain can be like driving in fog precisely because the tyres lift the water off the road and the wake of the car turns it in to mist.

[Tommy Cookers]

... It happens on road cars too and their tyres are cold, especially in wet weather.

not unless your road car tyres give zero energy losses .....
is this perpetual motion-type invention patented ?

police helicopter infra-red footage of nighttime pursuits show that the road is heated by the tyres for c.50 m
this effect is calculable from tyre resistance data - much of the resistance work going to heat the road
and worked-on water is heated

[Just_a_fan]

... It happens on road cars too and their tyres are cold, especially in wet weather.

presumably your road car tyres give zero energy losses .....
is this perpetual motion-type invention patented ?

police infra-red camera footage of nighttime vehicle pursuits show that the road is heated for 50-100 m behind the car
this effect is calculable from basic tyre resistance data

I was going to put the word "relatively" in there but I thought it obvious to all on a technical site that road tyres are "cold" compared to racing tyres that are generally "hot". F1 wet tyres run at several 10s of degrees C where a road tyre in the wet will be at perhaps 10-20 deg C.

Thermal imaging cameras generally show relative temperature, not absolute temperature. So the "hot" trail behind the car's tyres might only be a few degrees - certainly not enough to cause significant enough evaporation to create a dry line behind the car. The vastly more significant way that standing water is removed from the track is physically moving it with the tyre. Once the track is down to "damp", then heating will start to play an ever increasing effect.