Radiator core aero problem

[MIKEY_!]

Hi all,

This problem has been bothering me for a while, I have scoured the internet, a few books, and this forum and drawn a blank. As air passes through a radiator core (in F1 or otherwise), do the gaps between the tubes function as venturi tunnels? To my untrained eye, it seems that they would.

My (limited) understanding of radiator design tells me this is a problem because the venturi effect would lower the air pressure between the tubes and reduce heat transfer.

Does the shape of the radiator duct before the radiator slowing air down and increasing the air pressure negate this somehow?

What am I missing? Apologies if my understanding of radiator aero is way off.

[maunde]

The size of the channels through which the air passes is very small (I don't have an exact number) so you are likely to get choked flow as well as a high drop in pressure (unrecoverable) across the radiator. In CFD, radiators are often modelled as a porous medium, you could try reading up on that. Also, have a look at an orifice plate and the relation of choked flow - this may give you some info on back pressure.

[humble sabot]

You're fundamentally correct in that a properly designed rad duct will be designed to maximise pressure on the surface of the heat exchanger. I think maunde is correct in stating that the choking effect is going to be predominant. The lowest pressure part of the flow will be at the choke point, but as the air mass is picking up heat on its way through the tiny channel it'll start to want to expand helping velocity somewhat. The venturi effect will mean the maximum velocity is at the narrowest point, but it's a localised effect.

[Lotus102]

Does anyone know if F1 cars utilise the Meredith Effect? I’d be surprised if they didn’t

[maunde]

Does anyone know if F1 cars utilise the Meredith Effect? I’d be surprised if they didn’t

After briefly reading about this effect, I suspect the use of water will limit the extent to which it is used, as well as the limit on ram velocity relative to a plane. As was mentioned above, the air will still be heated (self explanatory), which may lend to a small decrease in drag from the radiators.