Feeding radiators hot air into Venturi tunnels?

[g-force_addict]

If rules were to allow tall tunnels, What do you guys think about feeding radiators hot air into the Venturi tunnels?

I just created a diagram to explain it better:

http://www.freeimagehosting.net/lm6jr
The blue box at the nose is the radiator, which is fed by air coming from the car grill.
The red lines are the Venturi tunnel profile. For diagram simplicity they are drawn as straight lines, instead of curved ones required for smooth aerodynamics.

Will hot (expanded) air actually help venturi tunnels downforce by feeding them with more air?
What do you guys think about this approach?

[flynfrog]

The P51 used the same approach to gain thrust from the cooling duct.

[flynfrog]

the problem with yours is you would need to feed the air after the nozzle

[WhiteBlue]

As you say tunnels are prohibited and not likely to re appear in F1. Patrick Head and Rory Byrne were advocating such a system in the FiA expert working group three or four years years ago. But he teams mainly for strategic reasons shot the plan down. They hate change and argued it would be too expensive to develop.

From a scientific point of view it will most likely work. If you heat up air it expands and that should accelerate the air flow into the tunnels which is the objective.

[g-force_addict]

the problem with yours is you would need to feed the air after the nozzle

Thanks a lot for your reply.

Let's suppose these Venturi tunnels also have exhaust blown diffusers...
Is it OK to feed radiator hot air right just after the nozzle in the mostly flat area (throat)?, or Do you need to feed it to the diffuser area?

[wesley123]

The Porsche 962(And I asume the 956 did too) did do that.

Customers however closed these exits off, and by that increased the L/D of the car.

The underfloor on early 962s, specifically the area that was just below the engine and forming the leading edge of the tunnels, was made out a single piece of bent aluminum. Initially the underfloor was vented with louvers to cool the engine by allowing the heated air to exit underneath the car, though this was quickly found to be detrimental to the car’s aerodynamics and closing the slots off became an easy way to increase the car’s L/D out of the box.

[Paul]

No surprise really, by introducing moderately heated air from intakes to the floor the pressure difference above and below the floor will diminish, and so will down force. Maybe if radiator intakes were themselves under the car, that could work...

[flynfrog]

the problem with yours is you would need to feed the air after the nozzle

Thanks a lot for your reply.

Let's suppose these Venturi tunnels also have exhaust blown diffusers...
Is it OK to feed radiator hot air right just after the nozzle in the mostly flat area (throat)?, or Do you need to feed it to the diffuser area?

you need to feed it some where from the nozzle back to be the most effective. You want the air to be dense at the nozzle and expand after.

[Just_a_fan]

The P51 used the same approach to gain thrust from the cooling duct.

The Meredith Effect. Used in the Spitfire radiator too, as it happens, before the P-51. The Spitfire was going to be evaporatively cooled but that didn't work very well so they stuck podded radiators (designed by Meredith) on it. These used the Effect to help offset the drag. =D>

[proutyc]

Could you gain back some of the lost L/D if the growth rate was increased at the point the hot air was introduced. In effect using this hot air to help reduce the effects of seperation?

Hope it makes sense and an interesting topic

[flynfrog]

The P51 used the same approach to gain thrust from the cooling duct.

The Meredith Effect. Used in the Spitfire radiator too, as it happens, before the P-51. The Spitfire was going to be evaporatively cooled but that didn't work very well so they stuck podded radiators (designed by Meredith) on it. These used the Effect to help offset the drag. =D>

Exactly I think they claim it made just enough thrust to overcome the drag from the duct. I just like the P51 better than the spit

[g-force_addict]

Could you gain back some of the lost L/D if the growth rate was increased at the point the hot air was introduced. In effect using this hot air to help reduce the effects of seperation?

Hope it makes sense and an interesting topic

Tnx but I don't quite get it. Would you mind to elaborate?

Or maybe, Can you PLEASE modify the original car image (without the radiator/venturi diagram) to understand it better?

I used plain Windows Paint to illustrate the idea and uploaded it in freeimagehosting.net (the first free image hosting search result I got in Google). You don't have to register to upload images.

And yes, It makes sense that you need the radiator near the nozzle, so it won't rob venturi tunnels throat or diffuser of their lower pressure.

[flynfrog]

Could you gain back some of the lost L/D if the growth rate was increased at the point the hot air was introduced. In effect using this hot air to help reduce the effects of seperation?

Hope it makes sense and an interesting topic

Tnx but I don't quite get it. Would you mind to elaborate?

Or maybe, Can you PLEASE modify the original car image (without the radiator/venturi diagram) to understand it better?

I used plain Windows Paint to illustrate the idea and uploaded it in freeimagehosting.net (the first free image hosting search result I got in Google). You don't have to register to upload images.

And yes, It makes sense that you need the radiator near the nozzle, so it won't rob venturi tunnels throat or diffuser of their lower pressure.

you could run a steeper diffuser due to the added expansion due to the temp increase