Front Wing Flow around Wheels

[quicksesh]

In the current Racetech magazine there is a piece about the Y250 vortex penned by Pat Symonds.
Basically because the centre 500mm of the front wing has to follow an FIA mandated profile, which is aerodynamically neutral, the holy grail of the aerodynamicist is to control this vortex (250mm either side of the centreline of the car Y axis).
The control is done by adding further vortices and this leads to extremely complex front wing elements, where the edge of each of the elements shed their own vortices which combine with the natural ‘Y250’ vortex.
Midboards are for controlling and directing front wheel wake and limiting its influence.

[Crucial_Xtreme]

Here's the piece in RaceTech quicksesh is talking about


Via RaceTech Magazine

Full page
http://imageshack.us/a/img844/4008/imagecht.jpg

Edit: although I'm not getting where he's talking about the Y250 vortex leading to more complex wings and says Ferrari's latest FW iteration is evidence of that. He lost me there. The turning vanes under the nose are on the Y250 axis but how he relates those to the FW baffle me.

[gixxer_drew]

Edit: although I'm not getting where he's talking about the Y250 vortex leading to more complex wings and says Ferrari's latest FW iteration is evidence of that. He lost me there. The turning vanes under the nose are on the Y250 axis but how he relates those to the FW baffle me.

The vortices interact. You can create a vortex somewhere else to control another vortex. I'm sure everyone remembers the things about tip vortex effect on wings to increase drag and decrease lift.

Let me give you an example from something you see in nature, a tornado. If you look at a clockwise rotation from the top down the right side is moving down, left side is moving up, top is to the right and bottom is to the left. So lets say there are two tornados in parallel one on the left and one on the right. As they get closer together and start to interact where they touch they will be flowing in opposite directions. Left side of one touches the right side of the other. Unless they are directly on above and below eachother any time they touch from any direction they will be flowing in opposite directions. The result is that they fight eachother for a moment until they converge into one bigger tornado.

Now the cause of the vortex formation never goes away and that forces them to merge until the air reaches equilibrium. Now with a car you have a forward velocity so a delay means not just a different moment in time but the car moves to different place in space during a delay at the rate of its velocity. So if you succeeded in delaying the formation of a single large vortex you succeeded in moving it to a different place on the car (relative to the car). With anything in aero, you will never stop the air from equalizing itself... but what you do is make it equalize in the right places so that your surfaces facing down get the low pressure side and the ones facing up get high pressures (a wing, etc). So by decreasing the vorticity in the immediate vicinity of the wing by creating vortex interactions you can improve its performance.

In essence, delay the formation of the big primary vortex. In the case of say the front face of a tire... a vortex could be desirable because all forces are reduced in dirty air as well. Since the tire and wing are so close to each other and the air at the front of the car is always the best quality, you can see the value in some really serious development there. There are also tricks with smaller vortices ahead of or inside of other vortices, and on and on. I reckon the aeros doing this stuff are learning something new every day.

A vertical fence parallel to vehicle centerline will shed a vortex any time the flow is not aligned to its orientation.

[Crucial_Xtreme]

The vortices interact. You can create a vortex somewhere else to control another vortex. I'm sure everyone remembers the things about tip vortex effect on wings to increase drag and decrease lift.

Let me give you an example from something you see in nature, a tornado. If you look at a clockwise rotation from the top down the right side is moving down, left side is moving up, top is to the right and bottom is to the left. So lets say there are two tornados in parallel one on the left and one on the right. As they get closer together and start to interact where they touch they will be flowing in opposite directions. Left side of one touches the right side of the other. Unless they are directly on above and below eachother any time they touch from any direction they will be flowing in opposite directions. The result is that they fight eachother for a moment until they converge into one bigger tornado.

Now the cause of the vortex formation never goes away and that forces them to merge until the air reaches equilibrium. Now with a car you have a forward velocity so a delay means not just a different moment in time but the car moves to different place in space during a delay at the rate of its velocity. So if you succeeded in delaying the formation of a single large vortex you succeeded in moving it to a different place on the car (relative to the car). With anything in aero, you will never stop the air from equalizing itself... but what you do is make it equalize in the right places so that your surfaces facing down get the low pressure side and the ones facing up get high pressures (a wing, etc). So by decreasing the vorticity in the immediate vicinity of the wing by creating vortex interactions you can improve its performance.

In essence, delay the formation of the big primary vortex. In the case of say the front face of a tire... a vortex could be desirable because all forces are reduced in dirty air as well. Since the tire and wing are so close to each other and the air at the front of the car is always the best quality, you can see the value in some really serious development there. There are also tricks with smaller vortices ahead of or inside of other vortices, and on and on. I reckon the aeros doing this stuff are learning something new every day.

A vertical fence parallel to vehicle centerline will shed a vortex any time the flow is not aligned to its orientation.

Maybe I didn't explain myself well enough. I get what you're saying mate, but if you look at the full page link I posted you'll see his comment about the Ferrari wing and how complex it is. Well I take that to mean towards the end plates where the 6 planes are. I'm figuring that's what he's saying is complex but that part of the wing is not on the Y250 axis correct, so I don't see what he's talking about in relation to Ferrari's "complex" FW and controlling the Y250 vortices.

[gixxer_drew]

The vortices interact. You can create a vortex somewhere else to control another vortex. I'm sure everyone remembers the things about tip vortex effect on wings to increase drag and decrease lift.

Let me give you an example from something you see in nature, a tornado. If you look at a clockwise rotation from the top down the right side is moving down, left side is moving up, top is to the right and bottom is to the left. So lets say there are two tornados in parallel one on the left and one on the right. As they get closer together and start to interact where they touch they will be flowing in opposite directions. Left side of one touches the right side of the other. Unless they are directly on above and below eachother any time they touch from any direction they will be flowing in opposite directions. The result is that they fight eachother for a moment until they converge into one bigger tornado.

Now the cause of the vortex formation never goes away and that forces them to merge until the air reaches equilibrium. Now with a car you have a forward velocity so a delay means not just a different moment in time but the car moves to different place in space during a delay at the rate of its velocity. So if you succeeded in delaying the formation of a single large vortex you succeeded in moving it to a different place on the car (relative to the car). With anything in aero, you will never stop the air from equalizing itself... but what you do is make it equalize in the right places so that your surfaces facing down get the low pressure side and the ones facing up get high pressures (a wing, etc). So by decreasing the vorticity in the immediate vicinity of the wing by creating vortex interactions you can improve its performance.

In essence, delay the formation of the big primary vortex. In the case of say the front face of a tire... a vortex could be desirable because all forces are reduced in dirty air as well. Since the tire and wing are so close to each other and the air at the front of the car is always the best quality, you can see the value in some really serious development there. There are also tricks with smaller vortices ahead of or inside of other vortices, and on and on. I reckon the aeros doing this stuff are learning something new every day.

A vertical fence parallel to vehicle centerline will shed a vortex any time the flow is not aligned to its orientation.

Maybe I didn't explain myself well enough. I get what you're saying mate, but if you look at the full page link I posted you'll see his comment about the Ferrari wing and how complex it is. Well I take that to mean towards the end plates where the 6 planes are. I'm figuring that's what he's saying is complex but that part of the wing is not on the Y250 axis correct, so I don't see what he's talking about in relation to Ferrari's "complex" FW and controlling the Y250 vortices.

Sorry if I misunderstood your question. I thought it made sense what he said in the article at least to me, but I'm not very up on the differences between the cars in the field either.

[aussiegman]

Maybe I didn't explain myself well enough. I get what you're saying mate, but if you look at the full page link I posted you'll see his comment about the Ferrari wing and how complex it is. Well I take that to mean towards the end plates where the 6 planes are. I'm figuring that's what he's saying is complex but that part of the wing is not on the Y250 axis correct, so I don't see what he's talking about in relation to Ferrari's "complex" FW and controlling the Y250 vortices.

So a quick recap:

The centre 500mm of the front wing is mandated to a specifc profile.
This leads to two separate drag inducing vortices 250mm from the centre line.
These then have cascade effects to items such as the floor and other areas of the car that reduces their effectiveness.

We all got that bit from the Y250 sidebar comment on the RaceTech article.

Just my guess from thinking about it (for 5 minutes):

If the Y250 vorticies could be effectively moved away from the centreline further to avoid turbulence under the car and around the sidepods, then you may be able to do this by pressure changes through shaping and direction of the airstreams away from the centreline.

The wing end plates are to direct flow around the tyres, but they can also be used to create an influential low pressure area on the inside portion of the wing area post flow by pulling air away from the open area between the Y250 line and the inside of the tyre. If you can reduce the pressure then the Y250 vorticies may be moved enough to help reduce their disturbance effect.

So if you can drag the voticies away from their normal flow direction by inducing a low pressure area next to them moving them away from their normal flow path (similar to how the "Coanda Effect" is used to drag exhaust flow away and direct it away from its normal flow path) you can either use other voticies to reduce their effect, remove flow disturbance from under the car to increase downforce due to smoothed flow or used the voticies for benefit in some other fashion/area.

This means the balancing of many influences at the outer edges of the front wing to get the desired effect of:

1) routing air away from the tyre
2) reducing pressure in the Y250 to inside tyre area
3) managing flow to the floor
4) managing flow over the tyre
5) managing flow into, over and around the sidepods.

As there are so many elements to consider, the wing shape is extremely complex and needs to account for the various interactions of the many flow variables around the area behind the wing.

Due to the area and profile of the front wing in the Y0 to Y250 distance of the horizontal plane being regulated, you need to mange the flow from the Y250 through indirect methodologies which create cascade effects to affect flow in other areas. Its a trade off but as has been seen can have significant effects and benefits.

My read on what was said is they are trying to not only reduce the drag from the Y250 voritices, but their influence on other areas like the floor which leads to the diffuser, around the sidepods which leads to the rear wing, getting the front wing to work efficiently in the first place etc etc.

As the front wing is the first thing the air interacts with on the car, then you must look at its entire effect as a holistic system as how the air comes off the front wing will dictate to a large extent how almost every other aero effect will perform.

[shelly]

http://www.f1technical.net/forum/viewto ... s&start=15

[shelly]

Vortices management in this case is aimed at downforce, not at drag reduction. The y250 vortex travels along the car and reaches the teatray, on whose side edges there are sections shaped like Ls or tunnels to house that vortex and exploit its low pressure for df. Further downstream there is interaction with the bargeboard vortex and the leading edge acceleration zone.
On this forum I remeber has been posted some time ago a video of a car (maybe force india) in spa in the wet (2010?) showing the y250 via its condensation trace.

In the picture I posted on the link the y250 vortex named as 3 interacts also with the tip vortex 4 from the inside side of the fw flap. Those are the vortices I think Symmonds is referring to.

As for low pressure effects of vortices of the underbody, some months ago it was posted on this forum a cfd picture of williams showing clearly the low pressure streaks fo vortices on the floor.

[aussiegman]

Vortices management in this case is aimed at downforce, not at drag reduction. The y250 vortex travels along the car and reaches the teatray, on whose side edges there are sections shaped like Ls or tunnels to house that vortex and exploit its low pressure for df. Further downstream there is interaction with the bargeboard vortex and the leading edge acceleration zone.
On this forum I remeber has been posted some time ago a video of a car (maybe force india) in spa in the wet (2010?) showing the y250 via its condensation trace.

In the picture I posted on the link the y250 vortex named as 3 interacts also with the tip vortex 4 from the inside side of the fw flap. Those are the vortices I think Symmonds is referring to.

As for low pressure effects of vortices of the underbody, some months ago it was posted on this forum a cfd picture of williams showing clearly the low pressure streaks fo vortices on the floor.

That previous post you linked to is a much more eloquent way of showing what I was thinking and could get out.

[allstaruk08]

ok im going to start by saying im really tired and its not helping me get my mind around it, but in directing airflow outside and around the wheel surely there has to be air going into that space where the redirected air flow came from so there will always be air in the place you've just redirected it from, there cant be nothing there can there? its properly twisting my mind =S lol

[hollus]

Thanks, allstaruk08, for making me go back and re-read this thread, now with the though in my head that something will still hit the wheel, no matter how much you deflect any bit of air.

The answer is then of course to have the less detrimental bit of air hitting the wheel. There is a very nice, long, complicated expatiation from Just_a_fan in page one of this thread. Here the most relevant bit (highlighting mine):

...the current wide front wing suffers from the front tyre interupting the free flow from approx. 30-40% of the active downforce producing surface of the wing. Thus any wing / wheel interaction will endeavour to do 3 things:
1. reduce the lift experienced by the tyre as this is working against the downforce and reduces the net grip available
2. reduce the drag caused by the tyre
3. increase the extraction of air from below the front wing (sometimes called scavenging the flow).

The flow coming off the front wing can go three ways: outside the tyre, over the tyre, inside the tyre.

We have seen, in the paper quoted by bhallg2k, that flow over the front tyre increases front tyre lift and drag. This is obviously not a good choice.

Directing the flow inwards is shown to be beneficial in the paper but it must be remembered that the paper talks about the 2009 front wing (i.e. the short span wing). That wing placed the endplate approx. in front of the inner shoulder of the front tyre. It makes sense in that situation to direct the flow / vortices inwards of the tyre...

So it is not as much about protecting the tire from being hit by air from the wing as about protecting the wing from the effects of air from the tire. I guess instead of from the most complicated part with all the cascades, it is now air from the inner, simpler, less sensitive and less important inner part of the front wing that hits the tyre and thus that suffers from the mess the tyre is doing with air around it.

[gixxer_drew]

I would venture to say its probably both reduce drag in front of the tire and improve forces on the wing since they are somewhat tied together....

[aussiegman]

ok im going to start by saying im really tired and its not helping me get my mind around it, but in directing airflow outside and around the wheel surely there has to be air going into that space where the redirected air flow came from so there will always be air in the place you've just redirected it from, there cant be nothing there can there? its properly twisting my mind =S lol

Yes as it is not a vacuum. But you can and will see pressure differentials in varying area's. So there is just "less" air there or the air has more velocity.

Systems, including those with gases, will always try and reach an equilibrium for pressure and temperature. Lower pressure areas will try and be "filled" by those with higher pressures. Lower temp state materials will try and increase their energy by taking it from higher energy state materials etc. Here you are just "directing flow" using pressure to bend an air stream.