Cooling fans

[xpensive]

What I think should be further investigated is to eliminate liquid as energy-conveyor, perhaps the Honda air-cooled
but fan-less 1968 Ra 302 had a point there?

[marcush.]

What I think should be further investigated is to eliminate liquid as energy-conveyor, perhaps the Honda air-cooled
but fan-less 1968 Ra 302 had a point there?

the big issue there is you need to direct air to the critical areas very precisely
to arrive at a useful temperature distribution on the engine without creating too much of backpressure inside the ducting but sure there is potential.Mind you the engine already transfers a lot of waste heat directly to ambient not through oil and water .With a mandatory weight of the engine I see not much reason why you could not have a fair bit of cooling ribs and air passages in the engine to enhance aircooling of the unit ....this could help reduce radiator size as well..

[xpensive]

I don't know much about relevant numbers here, but high-revving motorcyles was air-cooled for a long time, no?

[marcush.]

I don't know much about relevant numbers here, but high-revving motorcyles was air-cooled for a long time, no?

I think apart from BMW and Honda in the motorcycle business not much in terms of calculation ...

I think things depends on having a sufficient area /surface to dissipate heat.The Radiators have very elaborate fins with louvres these days and that´s a real big surface area ...I like to think with the help of todays simulation tools it should be possible to create the voids and surfaces necessary to manage the heat transfer direct aluminium to ambient air and dwarf the radiators for standstill ,pitstop and safetycar situations.

ssome Porsche Sportscars in the late 70s had watercooled cylinderheads and still retained the aircooled liners .If it was feasible back then ...I´m pretty sure the Turbo CanAm monsters had not much watercoolinmg going on ,did they?

[MIKEY_!]

Many bikes are air cooled. Although some use a joint system.

[riff_raff]

the big issue there is you need to direct air to the critical areas very precisely
to arrive at a useful temperature distribution on the engine without creating too much of backpressure inside the ducting but sure there is potential.Mind you the engine already transfers a lot of waste heat directly to ambient not through oil and water .With a mandatory weight of the engine I see not much reason why you could not have a fair bit of cooling ribs and air passages in the engine to enhance aircooling of the unit ....this could help reduce radiator size as well..

marcush,

The big Pratt & Whitney air-cooled radial piston aircraft achieved massive heat rejection rates. These engines had huge cylinder volumes, were supercharged to very high bmep rates, and had up to 4 rows of cylinders, using 1940's technology. I'm sure much better results could be achieved using 21st century materials and design tools. Check out the fin density of these air-cooled cylinders:




As for the engine coolant system:
"7.5 Coolant header tank :
The coolant header tank on the car must be fitted with an FIA approved pressure relief valve which is set to a maximum of 3.75 bar gauge pressure, details of the relief valve may be found in the Appendix to these regulations. If the car is not fitted with a header tank, an alternative position must be approved by the FIA.

7.6 Cooling systems :
The cooling systems of the engine must not intentionally make use of the latent heat of vaporisation of any fluid.

At one time, I believe only water was allowed as a coolant. I don't know if that is still true.

riff_raff

[marcush.]

riff raff ,

one big difference is the huge device pushing air thru that engine compartment +vehicle speed ...
But then I said I think you can enhance cooling big time adding surface...So I see your post confirming the idea to make more use of aircooling properties.

As for the water only cooling ..I doubt Charlie would realise what Nanofluids really is ..

As for the vapourisation ...not sure how this is to be read ..I thought this was only to prevent someone spraying the radiators with coolant not what you do inside the cooling system but sure this is a hot topic.

the high pressure is rising the boiling point of your coolant big time even though you have to cater for the grid and starting proceedure.

[xpensive]

ssome Porsche Sportscars in the late 70s had watercooled cylinderheads and still retained the aircooled liners .If it was feasible back then ...I´m pretty sure the Turbo CanAm monsters had not much watercoolinmg going on ,did they?

The Porsche 917/10 and 917/30 Can-Am cars were actually "oil-cooled" to some xtent, with a massive oil-flow
and a big fat radiator in front, but other than that it had the fan of course, reportedly stealing some 30 Hp.

[riff_raff]

riff raff ,

one big difference is the huge device pushing air thru that engine compartment +vehicle speed ...

marcush,

The reason I posted those pictures was to show an example of how effective air cooling an engine can be. Each one of those cylinders in the upper photo produced as much as 150hp. And in effect, there was nothing "pushing" air across the cooling fins of the engine's multiple rows of cylinders. The air velocity at the cowling exit was much greater than at the cowling inlet, which means it created a net thrust gain.

As I previously noted, the forged aluminum alloys used in those 1940's aircraft engines was limited to a safe structural temperature limit of around 275degF. There are modern wrought aluminum alloys (such as 2219) that can operate safely at temperatures approaching 600degF. Thus you would need much less cooling mass airflow to achieve your heat rejection rates.

riff_raff

[Edis]

This is a demonstration or display car. Look at the quality of the fan mounting system. Also, the ground surface looks like something you might find in a plaza or display room.

Brian

Can't see anything wrong with this cooling fan. On a demonstration car it's probably a good addition since speeds can be lower than on track, and you don't have to have people running around with fans.

marcush,

The big Pratt & Whitney air-cooled radial piston aircraft achieved massive heat rejection rates. These engines had huge cylinder volumes, were supercharged to very high bmep rates, and had up to 4 rows of cylinders, using 1940's technology. I'm sure much better results could be achieved using 21st century materials and design tools. Check out the fin density of these air-cooled cylinders:

As for the engine coolant system:
"7.5 Coolant header tank :
The coolant header tank on the car must be fitted with an FIA approved pressure relief valve which is set to a maximum of 3.75 bar gauge pressure, details of the relief valve may be found in the Appendix to these regulations. If the car is not fitted with a header tank, an alternative position must be approved by the FIA.

7.6 Cooling systems :
The cooling systems of the engine must not intentionally make use of the latent heat of vaporisation of any fluid.

At one time, I believe only water was allowed as a coolant. I don't know if that is still true.

riff_raff

If we look at aircraft engines, aircooled engines always had much lower bmeps than liquid cooled engines. The cooling performance also dropped off for each row of cylinders added while a liquid cooled engine could use 6 cylinders after each other without problem. This is also a reason why the V2 configuration became popular for motorcycles, it worked well with air cooling. Aircooled engines are usually restricted to two valves per cylinder.

Still, aircooling was popular for aircraft engines. Using aircooling means there were less that could go wrong, and no radiator that could be damaged by bullets. The loss in bmep was compensated for by simply making the displacement larger. A radial engine is after all quite space efficient.

[marcush.]

Two things there :

a racing car would never need a grid /finger guard-that alone will account for a loss of 2-4%of airflow...cannot imagine anyone in competition would sacrifice any perfromance .
Also a straight fanblade is much more efficient than those banana shapes..these are just for noise .Hardly a point of discussion in a f1 application.That fan is a convenience fit .Not engineered ..it´s there because it physically fits and it delays the overheating just enough for the job the car has to perform,in that sense there is nothing wrong with it .Still the electric drive will suffer big time under the temperature loads imposed by the application -a f1 car should have a fair bit more than 120°C downstream airtemps when current road cars with separate radiators are above 110°C these days.And in my book this is more an engine bay installation anyways ..and this is 120°C for a bone standard street car....Not suited that pretend drive(works a few hours at best)

[marekk]

We all probably know peltier effect semiconductor devices, but there is a lot of new research and developement in last years in the field of direct thermo-electric conversion.
Nanotechnology and new alloys are used, and they'll arrive already at quite high efficiency numbers - up to 20%. Not mass market ready yet, but should be interesting for Pinnacle Of Technology sport

[Edis]

Two things there :

a racing car would never need a grid /finger guard-that alone will account for a loss of 2-4%of airflow...cannot imagine anyone in competition would sacrifice any perfromance .
Also a straight fanblade is much more efficient than those banana shapes..these are just for noise .Hardly a point of discussion in a f1 application.That fan is a convenience fit .Not engineered ..it´s there because it physically fits and it delays the overheating just enough for the job the car has to perform,in that sense there is nothing wrong with it .Still the electric drive will suffer big time under the temperature loads imposed by the application -a f1 car should have a fair bit more than 120°C downstream airtemps when current road cars with separate radiators are above 110°C these days.And in my book this is more an engine bay installation anyways ..and this is 120°C for a bone standard street car....Not suited that pretend drive(works a few hours at best)

The fan appears to be a standard aftermarket fan with a standard aftermarket installation. The fan is probably intended to supply some flow when the car is stationary or running at low speed.

Curved blades tend to offer higher flow at low pressure ratios at the cost of less airflow at higher pressure ratios, but the difference isn't that great. That is also the case of finger guards vs. no finger guards.

The air temperature exiting the radiator will be a fair bit below 120 degC which is about the coolant temperature exiting the radiator. For a standard car you have an air temperature of about 60 degC after the radiator with a coolant temperature of 90 degC, although the air temperature can increase at standstill. Still, I would not expect any temperature related issues with the fan aside from possibly some reduction in life expectancy but that is hardly a problem for a F1 car.

[marcush.]

Two things there :

a racing car would never need a grid /finger guard-that alone will account for a loss of 2-4%of airflow...cannot imagine anyone in competition would sacrifice any perfromance .
Also a straight fanblade is much more efficient than those banana shapes..these are just for noise .Hardly a point of discussion in a f1 application.That fan is a convenience fit .Not engineered ..it´s there because it physically fits and it delays the overheating just enough for the job the car has to perform,in that sense there is nothing wrong with it .Still the electric drive will suffer big time under the temperature loads imposed by the application -a f1 car should have a fair bit more than 120°C downstream airtemps when current road cars with separate radiators are above 110°C these days.And in my book this is more an engine bay installation anyways ..and this is 120°C for a bone standard street car....Not suited that pretend drive(works a few hours at best)

The fan appears to be a standard aftermarket fan with a standard aftermarket installation. The fan is probably intended to supply some flow when the car is stationary or running at low speed.

Curved blades tend to offer higher flow at low pressure ratios at the cost of less airflow at higher pressure ratios, but the difference isn't that great. That is also the case of finger guards vs. no finger guards.

The air temperature exiting the radiator will be a fair bit below 120 degC which is about the coolant temperature exiting the radiator. For a standard car you have an air temperature of about 60 degC after the radiator with a coolant temperature of 90 degC, although the air temperature can increase at standstill. Still, I would not expect any temperature related issues with the fan aside from possibly some reduction in life expectancy but that is hardly a problem for a F1 car.

My data shows significantly higher air temps .Coolant temps of 90°C are non existant in modern cars..
As you surely know endurance of parts over temperatuire is anything but a linear function.A general rule of thump calls for half life expectancy for every rise of 10°C in ambient...the item we see on the picture may be lifed at 80°C ambient rated at 3000 working hours (maybe).But the estimated temps in that area may peak much higher throwing your calcs out of the window.And don´t forget a electric motor is producing a considerable amount of waste heat as well when working hard.