2014-2020 Formula One 1.6l V6 turbo engine formula

[gruntguru]

Turbine sizing in this application has nothing to do with boost, response inertia etc. The turbine will be sized to optimise a the package in terms of maximising the total of crankshaft and surplus turbine (MGUH) power. The package would be optimised to run at full load without the waste gate open. If the waste gate is open, the overall thermal efficiency is reduced and therefore the power is reduced. The waste gate is probably needed for emergency power mode - a low efficiency mode which makes higher power by extracting more than 120kW from the ES. The waste gate may also be used if the MGUH is not powerful enough to fully control boost at full load. It may also be used under decel conditions to reduce turbine drag under MGUH powered anti-lag conditions.

There are no easy generalisations like "a bigger turbine is better" or "more powerful" or "you want the compressor diameter as big as you can get it". The turbine and compressor are both sized to match the flow and pressure requirements of the optimised ICE package.

[chip engineer]

... The waste gate is probably needed for emergency power mode - a low efficiency mode which makes higher power by extracting more than 120kW from the ES. The waste gate may also be used if the MGUH is not powerful enough to fully control boost at full load. It may also be used under decel conditions to reduce turbine drag under MGUH powered anti-lag conditions.

Having a wastegate seems counterproductive to me. The oft cited need for protection during a failure of some component seems unnecessary; why not just cut fuel flow?
I agree that the emergency power mode could be useful, but having this (rarely used?) capability would seem to have a significant weight penalty (not only for the wastegate, also heavier electronics and ES to take more than 120kW from the ES).
Why would anyone want an MGU-H that 'is not powerful enough to fully control boost at full load'? Is it possible to get more from the MGU-H than the 120kW that could be sent to the MGU-K?
And why do you care about lag of boost pressure under decel conditions?

[Facts Only]

Rosberg wouldn't have made it to 2nd place in Montreal without a wastegate, once there was ERS failure it would have been the only way to control boost.
Admittedly it made no difference to the 2014 title but if it was a close battle then 18 points could easily tip the championship.
Also the 'overtake modes' with the wastegate open are used regularly in both quail' and race.

[chip engineer]

Rosberg wouldn't have made it to 2nd place in Montreal without a wastegate, once there was ERS failure it would have been the only way to control boost.
Admittedly it made no difference to the 2014 title but if it was a close battle then 18 points could easily tip the championship.
Also the 'overtake modes' with the wastegate open are used regularly in both quail' and race.

Hamilton didn't finish anyway with a similar failure. Do we know for certain that Rosberg had a complete ERS failure and that using a wastegate helped?
I can see using that overtake mode in qualifying, but it would seem to hurt overall performance during a race. Of course, one overtake can be very important. Is there some published info about using such a mode?

[Cold Fussion]

Rosberg wouldn't have made it to 2nd place in Montreal without a wastegate, once there was ERS failure it would have been the only way to control boost.
Admittedly it made no difference to the 2014 title but if it was a close battle then 18 points could easily tip the championship.
Also the 'overtake modes' with the wastegate open are used regularly in both quail' and race.

Hamilton didn't finish anyway with a similar failure. Do we know for certain that Rosberg had a complete ERS failure and that using a wastegate helped?
I can see using that overtake mode in qualifying, but it would seem to hurt overall performance during a race. Of course, one overtake can be very important. Is there some published info about using such a mode?

From memory, both cars had a total mgu-k failure and Hamilton then suffered a rear brake failure as a result. If the mgu-k suffers a total failure you wont be able to control the turbo with the mgu-h once the battery was fully charged. In this instance having the waste gate helped him finish second, but this was helped by the chasing cars have destroyed tyres on a difficult circuit to overtake on, pretty much any other circuit he would have finished outside the points.

[gruntguru]

... The waste gate is probably needed for emergency power mode - a low efficiency mode which makes higher power by extracting more than 120kW from the ES. The waste gate may also be used if the MGUH is not powerful enough to fully control boost at full load. It may also be used under decel conditions to reduce turbine drag under MGUH powered anti-lag conditions.

. . . And why do you care about lag of boost pressure under decel conditions?

The turbo spools down during decel. The MGUH needs to keep it spinning at an adequate speed in anticipation of the next throttle opening - that consumes energy.

[chip engineer]

... The waste gate is probably needed for emergency power mode - a low efficiency mode which makes higher power by extracting more than 120kW from the ES. The waste gate may also be used if the MGUH is not powerful enough to fully control boost at full load. It may also be used under decel conditions to reduce turbine drag under MGUH powered anti-lag conditions.

. . . And why do you care about lag of boost pressure under decel conditions?

The turbo spools down during decel. The MGUH needs to keep it spinning at an adequate speed in anticipation of the next throttle opening - that consumes energy.

OK, and I do see how a valve opening the compressor output to atmosphere would help there.
But it is still not clear to me how a wastegate helps with that unless air or exhaust is entering through the wastegate exit. Is that what you propose?

[gruntguru]

Yes it is not clear to me either - I don't know enough about radial inflow turbine characteristics in that mode. It is not inconceiveable however, that turbine drag would be lower at zero flow than at low/inadequate flow.

My conjecture that the wastegate may perform this function is based on exhaust noise from a video posted in another thread.

[Nickel]

All this talk about turbos and MGUH keeping the turbo spooled...

I wonder how simple it is to spool only the compressor via MGUH. Is this one of the benfits of the split design or is it simple to bypass the turbo and only power the compressor? I imagine there must be an energy savings of only driving one device, no?

[PlatinumZealot]

Turbine sizing in this application has nothing to do with boost, response inertia etc. The turbine will be sized to optimise a the package in terms of maximising the total of crankshaft and surplus turbine (MGUH) power. The package would be optimised to run at full load without the waste gate open. If the waste gate is open, the overall thermal efficiency is reduced and therefore the power is reduced. The waste gate is probably needed for emergency power mode - a low efficiency mode which makes higher power by extracting more than 120kW from the ES. The waste gate may also be used if the MGUH is not powerful enough to fully control boost at full load. It may also be used under decel conditions to reduce turbine drag under MGUH powered anti-lag conditions.

There are no easy generalisations like "a bigger turbine is better" or "more powerful" or "you want the compressor diameter as big as you can get it". The turbine and compressor are both sized to match the flow and pressure requirements of the optimised ICE package.

I am not gonna argue on this one. I did not say get as much boost as you can... I said you want the compressor to be a larger radius. A physically bigger compressor is more efficient. Check out the size of mercedes' compressor.

I disagree that u can just slap any turbo on as long as it can give your full load performance. Turbine sizing is very important for transient response . Why waste your precious battery charge to to make up for an illproperly sized and ill designed turbine?

[wuzak]

All this talk about turbos and MGUH keeping the turbo spooled...

I wonder how simple it is to spool only the compressor via MGUH. Is this one of the benfits of the split design or is it simple to bypass the turbo and only power the compressor? I imagine there must be an energy savings of only driving one device, no?

Compressor and turbine have to be on the same axis and rotate at the same speed at all times.

[wuzak]

Turbine sizing in this application has nothing to do with boost, response inertia etc. The turbine will be sized to optimise a the package in terms of maximising the total of crankshaft and surplus turbine (MGUH) power. The package would be optimised to run at full load without the waste gate open. If the waste gate is open, the overall thermal efficiency is reduced and therefore the power is reduced. The waste gate is probably needed for emergency power mode - a low efficiency mode which makes higher power by extracting more than 120kW from the ES. The waste gate may also be used if the MGUH is not powerful enough to fully control boost at full load. It may also be used under decel conditions to reduce turbine drag under MGUH powered anti-lag conditions.

There are no easy generalisations like "a bigger turbine is better" or "more powerful" or "you want the compressor diameter as big as you can get it". The turbine and compressor are both sized to match the flow and pressure requirements of the optimised ICE package.

I am not gonna argue on this one. I did not say get as much boost as you can... I said you want the compressor to be a larger radius. A physically bigger compressor is more efficient. Check out the size of mercedes' compressor.

I disagree that u can just slap any turbo on as long as it can give your full load performance. Turbine sizing is very important for transient response . Why waste your precious battery charge to to make up for an illproperly sized and ill designed turbine?

Because you get that back and more by having teh turbine sized for teh MGUh to make the maximum possible power.

[trinidefender]

One crucial factor when it comes to turbine and compressor sizing is efficiency maps. The designers have to try to match the high efficiency points of the turbine to the high efficiency points to the compressor.

This is currently one of the largest headaches in aviation gas turbine design. At current with a compressor and turbine both sized to fit into a packaging space such as the engine nacelle of an aircraft (or the space on top or in the the V of an engine, the turbines highest efficiency point is at a lot higher rpm than the compressors highest efficiency point.

Various methods have been use to counteract this such as rolls royce with their 3 shaft design vs the competitors 2 shaft. Then there is pratt and whitneys solution which has recently been certified, the PW1000G geared turbofan. This contains reduction gears to slow the compressor and fan speeds down on the low pressure shaft. Unfortunately neither option is viable in F1 as a result of the regulations (what a shame, they missed a chance for some real innovation to take place). However GE is working on a new technology on their compressor/fan blades for their LEAP engines. The concept is that the blades bend under high aerodynamic load resulting from high compressor RPM. I doubt it is being used as currently all teams use centrifugal compressors but all the same it is very interesting technology.

[PlatinumZealot]

Those are axial designs, yes it is much more difficult to match compressor and turbine. Much easier to do with radial. The key thing about a radial design is transient response and wide operating range. That is what separates it from a slow responding axial design.

In automotive applications, the turbine efficiency affects how much back pressure the engine sees. A more efficient turbine will need less pressure and less heat to transmit the torque. A more efficient compressor will give you more pressure and flow with less torque required (sort of a mirror image of the turbine). You can keep the same turbine and slap on a bi- ass inefficient compressor wheel and you have a monster of an engine. But if there is a boost limit or a back pressure limit and you need good drive-ability it is better to focus on refining the turbine and the compressor. Generally for wide operating range a larger compressor with a smaller Area to radius ratio is what you want. That gives a flatter boost vs flow curve. (The same for centrifugal pumps, the larger radius ones have flatter delivery curves).

And this is what we see here:

[mrluke]

Its difficult to get a sense of scale from the image but as turbos go, that doesn't look particularly big.