And aerodynamics?

Tips, advice and tips to lower your consumption, processes or inventions as unconventional engines: the Stirling engine, for example. Patents improving combustion: water injection plasma treatment, ionization of the fuel or oxidizer.
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Macro
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by Macro » 04/03/10, 16:00

My first crate was a fiesta with an orange peel paint .... She drank more than me ... : Cheesy:
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Thibaud
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by Thibaud » 26/01/11, 21:40

The photos placed on this thread are no longer visible, those concerning modifications such as plate radiator and flat bottom interest me particularly but I did not understand the principle of setting up the pressure in the compartment engine to improve aerodynamics.
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oiseautempete
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by oiseautempete » 27/01/11, 08:50

Overpressure of the engine compartment?
Normally, it is put in depression thanks to a fairing under the engine (system identical to the planes with engine with pistons), fairing provided with a deflector which causes a depression to suck the hot air ... close the entry of air is risky because the effect of depression works only when the vehicle moves at a sufficient speed so neither at a stop or at a low speed in the city ...
On certain cars calculated very just cooling level as for example the Citroën SM, there have been some effective modifications made by the owners: louvres grids to the wheel arches (vacuum zone), removal of a part of the seal to the rear of the hood (still a depression area) ...
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by I Citro » 27/01/11, 11:01

oiseautempete wrote:... removing a portion of the seal at the back of the hood (still a vacuum zone) ...
:frown:
Ah, you catch me there.
Normally the area between the end of the hood and the base of the windshield is a zone of overpressure and not of depression.
This promotes the adhesion of windshield wipers, the evacuation of rainwater, but also the intake of fresh air for the passenger compartment whose mouths are traditionally located between the back of the hood and the base windshield ... so incompatible with your postulate that would admit that in the cockpit air likely to be polluted because from the engine compartment ...

Those who rolled in 2CV understand me ... : Lol:
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Thibaud
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by Thibaud » 27/01/11, 14:19

I seem to have read about the forum that by putting a plate in front of the grille it forces the air to return with more force in the engine compartment so a bigger pressure is created and there would be a depression under the car which makes it possible to evacuate more effectively the heat and decrease by the same the Scx and therefore the conso. I will try to find all that.
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Thibaud
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by Thibaud » 27/01/11, 14:28

Andre wrote:Hello mountain bike

The biggest gain in a radiator is not at the entrance of the radiator but especially at the exit of the radiator from the experiments that are done with the Subaru engines on the aircraft
the trade-off between having an efficient radiator at low speed and high load while riding versus driving at maximum speed
it is to work the exit of air after the radiator and particularly it is the depression at the back that depends the efficiency of the cooling and that with the least drag
That is to say that all the air that crosses the radiator and that strolls around the engine, must exit in an aerodynamic way under the vehicle with a simple sheet its form makes a depression in the engine compartment and sends hot air almost parralelle under the floor.
Very few cars could have good air flow under the engine and radiator inlet, the DS had a nice design for flow under the car.
There is another point that will surely surprise you
it is the frontal section of a fuselage
a wide fuselage 2 people side by side and significantly more aerodynamic than a fuselage tandemly one behind the other and that despite the larger surface of the side by side
Many known aircraft with the same wing and the same engine
just the fuselage that changes there is a 15% to 20% more on speed next to it.
The first DC2 had a narrower fuselage, the DC3 was enlarged and they gained in speed, there are rules between the length versus the frontal surface.

Andre


Voillà, and I found someone who had tried to install a polystyrene plate but it had fallen on the road to the ardeche because of the rain, remains more than to find the message ...
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I Citro
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by I Citro » 27/01/11, 16:20

Thibaud wrote:Voillà, and I found someone who had tried to install a polystyrene plate but it had fallen on the road to the ardeche because of the rain, remains more than to find the message ...
Yes in aviation ... in car, the parameters are different, because a vehicle stopped in a traffic jam or at a red light must be able to evacuate its calories, without benefiting from the air flows due to the displacement ...

Finally, this flow is not comparable between an automobile and an airplane ...

However, there was a precedent in cars ...
A Voisin had for cooling system a concetric sytème with the exhaust tube which by venturi effect "extract" the calories of the engine by the rear.
Neighbor was also an aircraft builder ...
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by Thibaud » 27/01/11, 22:10

Okay, I understand better now, so unless I drive at 400km / h this process will not be applicable : Lol:
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oiseautempete
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by oiseautempete » 27/01/11, 23:20

citro wrote:
oiseautempete wrote:... removing a portion of the seal at the back of the hood (still a vacuum zone) ...
:frown:
Ah, you catch me there.
Normally the area between the end of the hood and the base of the windshield is a zone of overpressure and not of depression.
This promotes the adhesion of windshield wipers, the evacuation of rainwater, but also the intake of fresh air for the passenger compartment whose mouths are traditionally located between the back of the hood and the base windshield ... so incompatible with your postulate that would admit that in the cockpit air likely to be polluted because from the engine compartment ...

Those who rolled in 2CV understand me ... : Lol:


A 2cv is something different: the air intake is perfectly frontal and in addition the open flap channels the air dynamically (practical when it rains) ... this is absolutely not the case on a modern car on which there is a space much lower than the level of the bonnet and which serves in particular as "storage" for the wipers which are hidden there to avoid generating turbulence: this zone is therefore necessarily in depression, d '' elsewhere on a modern design car which has the air conditioning air intake at this location, without a fan, not a small amount of air enters, moreover I experienced it on one of my old cars whose fan had given up the soul ...
(Note that on the SM (on the CX also by the way) the air conditioning air intake is on the hood and not in front of the windshield, which excludes "pollution" of the air sucked in) .
I had the opportunity to study the hood of a microlight and you would be very surprised at the difficulty of finding a really overpressured area (to place the engine air intake and cooling air intakes cylinders optimally) because of the complexity of the flows (deviated it is true by the helical mixing of the propeller as well as by the variable incidence according to the speed of the machine in flight) ...
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by I Citro » 28/01/11, 11:41

oiseautempete wrote:A 2cv is something different: the air intake is perfectly frontal and in addition the open flap channels the air dynamically (practical when it rains) ... this is absolutely not the case on a modern car on which there is a space much lower than the level of the hood and which serves in particular as "storage" for the wipers which are hidden there to avoid generating turbulence: this area is therefore necessarily in depression, moreover, on a modern design car that has the air-conditioning intake at this place, without a motor-fan it does not enter a fart of air, moreover I experienced it on one of my old cars whose fan had made the soul...
Are you sure? :?:
I have in mind a sketch of aerodynamic pressure zones on a citroën Visa or they explain, illustration to the support, my previous remark. For having owned several Visa, I inform you that ventilation cold air was done without electric fan, only in dynamic ...
How do you explain if the air inlet is in depression ... :?


On "modern vehicles", the distribution of the air has become much more complex causing significant pressure drops due to the many air vents (it is not uncommon to have vents in the rear seats of a minivan) , with 2 exchangers (air conditioning evaporator and heating coil) as well as the cabin filter. Nothing surprising, therefore, that we do not feel the air flow in dynamics compared to cars without air conditioning and without cabin filter ... :?
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