Author Topic: Prototype in the wind tunnel  (Read 2078 times)

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Offline jbcollier

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Prototype in the wind tunnel
« on: Saturday,January 09, 2021, 06:57:38 PM »

Offline Bainford

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Re: Prototype in the wind tunnel
« Reply #1 on: Saturday,January 09, 2021, 08:54:57 PM »
Interesting photo. Note how the tufts on the engine cover are doing something different than all the rest.
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Offline MRN I J

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Re: Prototype in the wind tunnel
« Reply #2 on: Sunday,January 10, 2021, 08:10:26 AM »
not really indicative how the air flows through the vents into the engine compartment and out through the rear grille though
Regards Chris

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Offline jbcollier

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Re: Prototype in the wind tunnel
« Reply #3 on: Sunday,January 10, 2021, 08:56:13 AM »
Air flows in through the rear grill.  Not supposed to, but it does.

Offline MRN I J

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Re: Prototype in the wind tunnel
« Reply #4 on: Sunday,January 10, 2021, 12:35:06 PM »
Air flows in through the rear grill.  Not supposed to, but it does.

And out ?
Regards Chris

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Oldest existing LR Discovery S3, one of 1st 125 hand built cars
Peugeot 406 with less than 55k miles on it

Offline jbcollier

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Re: Prototype in the wind tunnel
« Reply #5 on: Sunday,January 10, 2021, 12:53:23 PM »
Sadly, no.  Engine compartment air recycling is a big issue.  What is needed are "positive" air scoops that force air in when the car is moving.  That would insure flow out.  The $64,000 question is how to do that in an aesthetically pleasing way.

Offline MRN I J

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Re: Prototype in the wind tunnel
« Reply #6 on: Sunday,January 10, 2021, 01:44:59 PM »
Lou's photos on page 1 of the 47 pics has a good period photo of a scoop, seeing as the NACA duct doesn't supply enough air
Regards Chris

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Aston Martin DB MkIII DHC (wifes)
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Oldest existing LR Discovery S3, one of 1st 125 hand built cars
Peugeot 406 with less than 55k miles on it

Offline MRN I J

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Re: Prototype in the wind tunnel
« Reply #7 on: Sunday,January 10, 2021, 01:50:53 PM »
sorry, your photo on page 2 of Lou's thread
Regards Chris

other cars inc wifes cars
Aston Martin DB MkIII DHC (wifes)
Aston Martin DB2 Saloon (shared)
MkI Austin Cooper S with less than 50k miles on it
Oldest existing LR Discovery S3, one of 1st 125 hand built cars
Peugeot 406 with less than 55k miles on it

Offline MRN I J

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Re: Prototype in the wind tunnel
« Reply #8 on: Sunday,January 10, 2021, 02:16:18 PM »
Air flows in through the rear grill.  Not supposed to, but it does.

That would pull exhaust fumes in to the engine bay (and to the cockpit?), so every engine needs an airbox & be fed externally in reality
Regards Chris

other cars inc wifes cars
Aston Martin DB MkIII DHC (wifes)
Aston Martin DB2 Saloon (shared)
MkI Austin Cooper S with less than 50k miles on it
Oldest existing LR Discovery S3, one of 1st 125 hand built cars
Peugeot 406 with less than 55k miles on it

Offline jbcollier

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Re: Prototype in the wind tunnel
« Reply #9 on: Sunday,January 10, 2021, 02:35:21 PM »
Yes, it does.  Not "all" the exhaust gets pulled in, but some for sure.  Air comes in through the front of the wheel wells where the box-section, radius arms run.  It goes up and out the cover vents and tumbles back.  Some gets goes down and back in leading to high engine compartment temperatures, as much as twenty over ambient.  In stock form, the best source of cool air is low in the front of the engine compartment.

Offline jbcollier

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Re: Prototype in the wind tunnel
« Reply #10 on: Sunday,January 10, 2021, 03:16:16 PM »
These scoops work:





Aesthetically?  Not so much.  I'm thinking of running something similar but only on the driver's side (won't block rear view) and not venting into the cover but through side above the tank and ducted low to enhance through-flow.  Just thinking though, nothing mocked up.

Offline Sandyman

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Re: Prototype in the wind tunnel
« Reply #11 on: Sunday,January 10, 2021, 03:27:54 PM »
John, I am thinking of the same thing. Sketching out some ideas. Single detachable scoop behind driver.

Offline jbcollier

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Re: Prototype in the wind tunnel
« Reply #12 on: Sunday,January 10, 2021, 04:08:29 PM »
Love to see what you come up with.

Offline Richard48Y

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Re: Prototype in the wind tunnel
« Reply #13 on: Sunday,January 10, 2021, 06:12:59 PM »
Rear screen can be blocked if this is really a problem.
Modern 12v fans can move a fair amount of air, maybe rear mount fans would expel air far enough to stop the tumbling recirculation?
Have to wonder how effective a flat extension above the rear vent might be. Not attractive, but how effective?
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Offline SteelCityLotus

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Re: Prototype in the wind tunnel
« Reply #14 on: Sunday,January 10, 2021, 07:55:04 PM »
Yes, it does.  Not "all" the exhaust gets pulled in, but some for sure.  Air comes in through the front of the wheel wells where the box-section, radius arms run.  It goes up and out the cover vents and tumbles back.  Some gets goes down and back in leading to high engine compartment temperatures, as much as twenty over ambient.  In stock form, the best source of cool air is low in the front of the engine compartment.

I would be interested to see if blocking the engine cover vents forced the engine bay air to be sucked out of the number-plate vent. The car did not originally have a vent in the number plate area, at least mine doesn't, so that means the engine cover vents were necessary to extract heat. By adding a vent at the rear and blocking the engine cover, the pressure in the engine bay would not bleed out of the engine cover and, instead, bleed into the low pressure wake at the rear. NACA ducts or underbody modifications in addition to blocking these vents may also help keep air moving through the engine bay.

Is there a good 3D CAD model of the Europa available? I have CFD software on my company laptop and I've been itching to use it. I'm a novice with regards to the Europa, but I have a pretty solid education on motorsports aerodynamics.