57 replies to this topic

[Wuzak]

During the last turbo era there didn't seem to be much use of ram air into the turbocharger.

Is this because all that would be achieved when using ram air would be that slightly less exhaust energy would be needed to compress the air the required amount?

I haven't seen any word on the chassis rules as regards the airbox cover and intake for the new turbo era. Are they keeping the top entry?

As the new engines will be turbocharged and turbocompounded, would using ram air be more useful in the past. That is, will it provide enough of a pressure rise on the turbo inlet that the turbo doesn't have to work as hard to get the required boost pressure, allowing the compounding unit to recover more energy?

If so, will the extra power compensate for the drag of the engine cover?

[cheapracer]

If so, will the extra power compensate for the drag of the engine cover?

Good question, I think no and they will run low mostly because they will be boost limited and won't need to seek extra air from a source that as you suggest will offer increased drag.

Hopefully will see the loss of those ridiculous fins as well.

[Magoo]

Assuming standard air density of .076 lb.cu ft (fair enough) and 100 percent efficiency of the air inlet device (fat chance) the inertial ram effect is around .18 psi at 100 mph and .7 psi at 200 mph.

So if you can figure out how to not slow down for the corners, maybe you have something. Once again, the chassis and tire people are not holding up their end.

[Tony Matthews]

I thought the low-deck turbo cars looked cool, but it is such a large, 'vertical' area that sponsors would be miffed if it were not available.

[Magoo]

Let's just get it over with. KERS and DRS are fully adaptable to this configuration.

[cheapracer]

KERS and DRS are fully adaptable to this configuration.

Once again, the chassis and tire people are not holding up their end.

You're like mayonnaise, you're on a roll tonite

[Canuck]

Assuming standard air density of .076 lb.cu ft (fair enough) and 100 percent efficiency of the air inlet device (fat chance) the inertial ram effect is around .18 psi at 100 mph and .7 psi at 200 mph.

I find that remarkable (though not expressing disbelief) considering the extra effort required to cycle home Friday in a 50km/h headwind. (yes yes, I understand we're talking different features of the same substance)

[Wuzak]

Assuming standard air density of .076 lb.cu ft (fair enough) and 100 percent efficiency of the air inlet device (fat chance) the inertial ram effect is around .18 psi at 100 mph and .7 psi at 200 mph.

So if you can figure out how to not slow down for the corners, maybe you have something. Once again, the chassis and tire people are not holding up their end.

So, not really any gain.

[gruntguru]

I find that remarkable (though not expressing disbelief) considering the extra effort required to cycle home Friday in a 50km/h headwind. (yes yes, I understand we're talking different features of the same substance)

If a 100kg human had a terminal velocity of 100 mph, the drag power would be about 44kw. Consequently it would take about that to cycle upright at 100mph. If the stagnation pressure at 100mph is 0.18 psi as suggested in Magoo's post, CdA for the 100kg human would be about 0.8 sq m (which is in the ballpark although a little high - as you would expect since terminal velocity is closer to 120 mph). The force (drag) by the way is 100kg and scaling it back to 50 km/hr for your example gives about 10kg of drag which is still a lot for a cyclist. On the other hand if you are pedalling at 30kph with no headwind the (projected) drag is 3.5 kg (290 Watts power). With the 50 kph headwind (80k apparent) the drag becomes 25 kg and the power requirement goes up to 2100 Watts.

Getting back to F1, if the engine breathes 0.5 cu m/s of air, the work done by a ram air intake at 0.7 psi (4.7 kPa) is p x dv/dt = 4.7 x 0.5 = 2.35 kW. This is the reduction in turbocharger compressor work requirement and is probably worthwhile but not earth-shattering.

[bigleagueslider]

wuzak,

The centrifugal compressor on a typical turbocharger is a dynamic compression device. The pressure and mass flow it can produce is a function of the compressor inlet density, temperature, and velocity. If the compressor is designed to operate at a certain PR, then obviously a ram air duct that achieves a higher dynamic air pressure at the compressor inlet will likely result in a greater pressure at the discharge. Flow velocities and vectors at the compressor inlet are also important with regards to compressor performance.

During the last turbo era in GP racing, there was use of ram air engine air inlet ducts (usually "snorkle" or "periscope" ducts) on the cars. With engine inlet ram air ducts, the increase in engine power they provide is usually more than offset by the additional drag they create. This is true for turbo cars as well as N/A cars.

slider

[Wuzak]

wuzak,

The centrifugal compressor on a typical turbocharger is a dynamic compression device. The pressure and mass flow it can produce is a function of the compressor inlet density, temperature, and velocity. If the compressor is designed to operate at a certain PR, then obviously a ram air duct that achieves a higher dynamic air pressure at the compressor inlet will likely result in a greater pressure at the discharge. Flow velocities and vectors at the compressor inlet are also important with regards to compressor performance.

During the last turbo era in GP racing, there was use of ram air engine air inlet ducts (usually "snorkle" or "periscope" ducts) on the cars. With engine inlet ram air ducts, the increase in engine power they provide is usually more than offset by the additional drag they create. This is true for turbo cars as well as N/A cars.

slider

Thanks slider.

If the drag is more than the extra power they make, then why do it?

In the new turbo era the turbo will have a MGU which will capture some of the exhaust energy that is not required to spin the turbo. If the pressure of the inlet is higher thenn the turbo won't need to spin as fast to get the desired output, and the difference in power required to compress the air will be converted by the MGU and transferred to the KERS motor.

[cheapracer]

If the drag is more than the extra power they make, then why do it?

Well it would appear historically speaking that it does work for N/A and not for turbo's even in unlimited times.

[Wuzak]

With engine inlet ram air ducts, the increase in engine power they provide is usually more than offset by the additional drag they create. This is true for turbo cars as well as N/A cars.

If the drag is more than the extra power they make, then why do it?

Well it would appear historically speaking that it does work for N/A and not for turbo's even in unlimited times.

It seems that slider doesn't think it does.

[MatsNorway]

With a direct throttle valve you might get trouble if the engine is maxed without the ram effect designed in.

You could ofc go higher on the comp but then you have to reduce throttle valve opening at peak power to avoid knock. But you would gain above and below Peak power.

what does the people think?

Edited by MatsNorway, 28 June 2011 - 16:13.

[gruntguru]

All just things that have to be included in the design. For turbo engines the wastegate system will regulate the boost regardless of help from ram air. For NA engines knock is unlikely to be a significant factor at 200 mph / peak power RPM. The big difference is this.

For NA engines the 0.7 psi boost is significant - probably worth about 5% power increase at the cost of a few kW in drag.

For turbo engines it is usually possible to crank up the boost in the absence of a ram air device. In many cases the boost is limited by regulations anyway. So the options are do we use ram air and cop the drag penalty or do we live with a slight increase in exhaust back pressure (say 0.5 psi). The back pressure will probably have a lower power penalty and durability (exhaust temp) shouldn't be an issue because with rear facing exhausts the back pressure will be higher at low vehicle speed / max power anyway.

[Powersteer]

Probably direct air intake to the atmosphere in a head on with the air stream would be designed into the turbo to seek the lowest intake tempurature as primary and then intake turbulence reduction.

[gruntguru]

Yes. I am also sure there would be a location on the bodywork where stagnation pressure could be utilised without the extra drag caused by the usual intake pod.

[Greg Locock]

I'd be rather more interested in the air temperature at the intake valves than worrying about ram effects.

[Tony Matthews]

One way of doing it...

[gruntguru]

Tony is that a heated air intake? It seems to be drawing warm air coming off the intercooler. I know Honda ran the RA168E with elevated (70*C) charge air temp but I always assumed they simply controlled the intercooling to achieve this. Did they also heat the air before the turbo compressor? That doesn't make sense as it would increase the compressor work requirement.

[Tony Matthews]

As you can see, gg, the duct to the turbo is getting its air from the same ducting as the intercooler, and it certainly looks as though that air must be passing through the outer few rows of that cooler. When I get a moment I'll look out my reference photos and see how it looks from the front. I have no idea about the temperature gradient of the intercooler, whether the air is hot, warm or cool at that outer edge. Perhaps it was a way, if it was adjustable, to control the ultimate charge temperature.

[Wuzak]

I'd be rather more interested in the air temperature at the intake valves than worrying about ram effects.

Tony is that a heated air intake? It seems to be drawing warm air coming off the intercooler. I know Honda ran the RA168E with elevated (70*C) charge air temp but I always assumed they simply controlled the intercooling to achieve this. Did they also heat the air before the turbo compressor? That doesn't make sense as it would increase the compressor work requirement.

So are we likely to see similar inlet temperatures again?

Is it counterproductive doing it the way that is shown in Tony's drawing? Would it be easier to have a cold air intake and a smaller inetrcooler?

What sort of boost will be required for a 1.6l v6 engine of around 600hp at, probably 12k rpm? What sort of temperatures would that equate to post compressor?

[MatsNorway]

Guessing 2.5bar.. but since its F1.. 2bar. because i like to guess..

[gruntguru]

So are we likely to see similar inlet temperatures again?

I would think so. Volumetric efficiency will be sacrificed to maximise fuel efficiency.

Is it counterproductive doing it the way that is shown in Tony's drawing? Would it be easier to have a cold air intake and a smaller inetrcooler?

It is counterproductive. More compressor work is required. A better way would be a thermostat controlled bypass valve to mix hot charge ex-compressor with cooled charge. Controlling the cooling airflow to the intercooler would work although a little slower in response.

What sort of boost will be required for a 1.6l v6 engine of around 600hp at, probably 12k rpm? What sort of temperatures would that equate to post compressor?

2 bar boost 185 deg C (at 70% compressor efficiency)

[Wuzak]

I would think so. Volumetric efficiency will be sacrificed to maximise fuel efficiency.


It is counterproductive. More compressor work is required. A better way would be a thermostat controlled bypass valve to mix hot charge ex-compressor with cooled charge. Controlling the cooling airflow to the intercooler would work although a little slower in response.


2 bar boost 185 deg C (at 70% compressor efficiency)

Thanks Grunt.

[gruntguru]

BTW about 80kW to drive the compressor.

[Wuzak]

BTW about 80kW to drive the compressor.

What sort of power could the turbine produce then? ie how much extra power for compounding?

[gruntguru]

At that massflow (about 0.5kg/s) every 100kW extracted drops the exhaust temp about 200-250*C so there might be as much as 200 kW available (less the 80kW to drive the compressor). Of course the returns are diminishing - as exhaust back-pressure rises, so do pumping losses, causing crankshaft power to fall.

[bigleagueslider]

As gruntguru notes, the important metric with turbocharging is mass flow, and not volume. Since a turbocharger is basically a free turbine dynamic compressor, the work between the turbine and compressor wheels must always be in equilibrium. The pressure ratio and mass flow of the compressor is affected by inlet charge density, flow velocity and direction, and the compressor angular velocity. All other things being equal, having cool air with high dynamic duct pressure at the compressor inlet will give the best result.

As for the picture of the Williams/Honda posted by Tony Matthews, there would be no logical reason to preheat the turbo inlet air by passing it across the intercooler core first. Maybe the guy that did the illustration was using a bit of "artistic license".

slider

[Todd]

I reckon the rear wing is more effective when there isn't a big airbox in front of it.

[Wuzak]

I reckon the rear wing is more effective when there isn't a big airbox in front of it.

That is probably correct. Remember a few years ago, around 2003/4, the airboxes were getting slimmed right down until teh FIA decreed the minimum size, and we ended up with those fins.

[Tony Matthews]

As for the picture of the Williams/Honda posted by Tony Matthews, there would be no logical reason to preheat the turbo inlet air by passing it across the intercooler core first. Maybe the guy that did the illustration was using a bit of "artistic license".

So, three options, perhaps the one I drew - and I can't remember why I chose that variant - was for cold weather! The 'snorkel' looks nicer! As to 'artistic license', that's for artists...

Edited by Tony Matthews, 01 July 2011 - 17:29.

[MatsNorway]

Thanks Tony.

Would be interesting to know the years these layouts raced. or if the ram air and fresh air intakes was used for quali only if they where allowed to do such things at the time.

Hot air intake or not will stand on how big the fuel tank is compared to the allowed fuel flow. Personally i think they need to have a bigger fuel tank than fuel flow so that they can race all the way to the finish line. no more "mix 4 lewis you are too low on fuel"

Personally im not convinced they will run hot air intakes even with small fuel tanks but what do i know..

[OfficeLinebacker]

So, three options, perhaps the one I drew - and I can't remember why I chose that variant - was for cold weather!

maybe cos it was the easiest to draw/figure out?

On that middle one, I can't work out exactly where that thing is getting the air from...I can't imagine a rectangular hole in the sidepod for intake air?

[Tony Matthews]

maybe cos it was the easiest to draw/figure out?

...I can't imagine a rectangular hole in the sidepod for intake air?

I never went for the easy option Offie, I like a challenge! As to the middle one, yes, a hole in the side, probably in a high-pressure area ahead of the rear wheel. I know the radiator eflux is just ahead of it, but I'm assuming Williams knew what they were doing... Not quite a rectangle, a sort of truncated NACA duct.

[nodrift4me]

I suspect there is a gap between the end of the intercooler and the piping so the inlet can get cool air.

[Wuzak]

Hot air intake or not will stand on how big the fuel tank is compared to the allowed fuel flow. Personally i think they need to have a bigger fuel tank than fuel flow so that they can race all the way to the finish line. no more "mix 4 lewis you are too low on fuel"

The fuel tank size will be limited, and probably will be smaller than that which would be required to run flat out all the way.

[Tony Matthews]

I suspect there is a gap between the end of the intercooler and the piping so the inlet can get cool air.

Not as far as I know - the intercooler was the same in all cases.

[Scotracer]

Hehe I like it when people don't realise you're the 'real' Tony Matthews.

[Powersteer]

maybe having the air intake right at the front of the car would have it at the highest state of static pressure, i dont know. i was thinking more in line with what happens at the bottom of a windscreen where pressure build up is use to blow dashboard air vents, now if you take that concept to the very front of the car we might get an exaggeration of the concept. im curious that lots of people mount their intercoolers so low up the front while the car has been lowered because i wonder how much road heat or the lack of it goes through the intercooler. looks like ill have to get someone to drive the car and stick my shoulders out using my hand to feel how hot is it down there!

[nodrift4me]

Not as far as I know - the intercooler was the same in all cases.

Okay -It'd be good to see it from a better angle so we can be sure though.

[Tony Matthews]

Hehe I like it when people don't realise you're the 'real' Tony Matthews.

I'm not, he's on holiday, I'm just a stand-in.

[WhiteBlue]

In the new turbo era the turbo will have a MGU which will capture some of the exhaust energy that is not required to spin the turbo. If the pressure of the inlet is higher thenn the turbo won't need to spin as fast to get the desired output, and the difference in power required to compress the air will be converted by the MGU and transferred to the KERS motor.

Potentially they could also use battery power to spool up the compressor to avoid turbo lag. They can drop the waste gate and regulate the turbo completely from the MGU.

As for the picture of the Williams/Honda posted by Tony Matthews, there would be no logical reason to preheat the turbo inlet air by passing it across the intercooler core first.

AFAIK the Honda was running on high octane fuel which was 88% based on toluene. Toluene boils at 111°C. They needed to preheat the air/fuel mix at that time to evaporate the fuel. Perhaps they heated the air and not the fuel to get the mixture to the evaporation point.

So, three options, perhaps the one I drew - and I can't remember why I chose that variant - was for cold weather!

Or it was caused by the fuel.

Edited by WhiteBlue, 02 July 2011 - 22:58.

[bigleagueslider]

So, three options, perhaps the one I drew - and I can't remember why I chose that variant - was for cold weather! The 'snorkel' looks nicer! As to 'artistic license', that's for artists...

The first picture looks like the inlet duct actually passes outside of the intercooler core. But what is even more interesting about that picture is there appears to be a bypass valve and piping around the outside of the intercooler core. I wonder if the device was "active"?

slider

[gruntguru]

AFAIK the Honda was running on high octane fuel which was 88% based on toluene. Toluene boils at 111°C. They needed to preheat the air/fuel mix at that time to evaporate the fuel. Perhaps they heated the air and not the fuel to get the mixture to the evaporation point.

http://www.zzw30.com...A168EEngine.pdf
They did both - maintained the charge air at 70*C using an intercooler bypass and the fuel at 80*C using a cooling water heat exchanger. Heating the intake prior to the turbo compressor would increase the compressor work so it would be interesting too find out why they did this on some models. Perhaps a "cold climate" option as Tony suggested?

Edited by gruntguru, 03 July 2011 - 05:31.

[Tony Matthews]

The first picture looks like the inlet duct actually passes outside of the intercooler core. But what is even more interesting about that picture is there appears to be a bypass valve and piping around the outside of the intercooler core. I wonder if the device was "active"?

slider

Active indeed...

Edited by Tony Matthews, 03 July 2011 - 18:01.

[MatsNorway]

Heeey!

Is that to bypass the intercooler?

reducing cooling but improving the volume circulating?

making the engine work better at low boosts.

Making the turbo kick inn earlier and making the car more drivable with a wild spec.

Edited by MatsNorway, 03 July 2011 - 18:48.

[J. Edlund]

http://www.zzw30.com...A168EEngine.pdf
They did both - maintained the charge air at 70*C using an intercooler bypass and the fuel at 80*C using a cooling water heat exchanger. Heating the intake prior to the turbo compressor would increase the compressor work so it would be interesting too find out why they did this on some models. Perhaps a "cold climate" option as Tony suggested?

The preheating could be used to keep the charge air temperature up during part load if there is some thermal inertia in the intercooler, but otherwise I can't think of a reason to heat the air before the compressor.

From what I seen about the new regulations the V6 should use a single turbocharger. Seems like a packaging nightmare to me. Higher revs too, 15k instead of 12k rpm. That will probably cost a bit in terms of specific fuel consumption.

Heeey!

Is that to bypass the intercooler?

reducing cooling but improving the volume circulating?

making the engine work better at low boosts.

Making the turbo kick inn earlier and making the car more drivable with a wild spec.

The bypass is used to keep the charge air temperature at 70 degC, done to improve vaporisation of the toluene based fuel.

[Powersteer]

Intercooler bypass seems very interesting, for fuel economy reasons which the Honda had an advantage. The intake through the intercooler is strange but another idea other than climate would maybe be a heat circulation concept, the intercooler is cooled by the intake so whatever is lost through intake heat is made up by the velocity it created on the air velocity going through the intercooler, lower speeds makes it sound practical but I'm sceptical, just theorizing. Another way to see this is maybe this is to make the bypass heat retention more effective and not lose too much when the intercooler is used through the circulation concept but then again, intercooler won't be hot when it is not charged. Intake air flow would be very bad though so probably this is used on tighter circuits where horsepower is not as critical.

[MatsNorway]

The bypass is used to keep the charge air temperature at 70 degC, done to improve vaporisation of the toluene based fuel.

That i understood but i was thinking it might had some gains to the future engines.

But now i don`t know what to think. i see some problems.

Edited by MatsNorway, 04 July 2011 - 09:38.