Mercedes Power Unit Hardware & Software

[Tommy Cookers]

What advantage do the vanes serve?

they enable airflow adjustment with lower losses than eg a butterfly throttle would
(eg for cruise an airliner has the IGVs deployed)

in most circumstances they are improving the efficiency of the compressor
so reducing the energy it requires - freeing more energy for electrical generation by the MGU-H

iirc these (variable geometry) vanes have only been allowed in F1 in the last 4 or 5 years ?

[johnny comelately]

1. the change to a curved blade as distinct from the normal flat blade, so much like a ships propeller
2. the blade arpetures are more capturing, this is a more progressed version of the clipping of every second blade in some of the performance turbos. This reduces cavitation too.
3, the outer introducing blades are to reduce turbulent introduction giving more mass supply to the compressor bladed, same as any aero on the rest of the car. The could eventually go much closer, ie, longer, to the compressor
4. as per standard the outer ring takes care of the boundary flow air, check the Garrett literature which is quite good
5. this may be of interest re e-turbos https://www.garrettmotion.com/electric- ... Ea2Tyk25eu
6. IMHO

[saviour stivala]

The Garret electric turbo innovation was a joint venture with Mercedes Benz. A 4cm 48-volt electric motor. With the turbo capable of reaching 170K rpm. But around four-five years before that Audi also used a 48-volt supercharger.

[saviour stivala]

Electric turbo versus electric supercharger (road car use). Provided they are used on equivalent engines the electric supercharged engine will produce more power while the compressor is being electrically powered by same voltage/same motor.

[Tommy Cookers]

Electric turbo versus electric supercharger (road car use). Provided they are used on equivalent engines the electric supercharged engine will produce more power while the compressor is being electrically powered by same voltage/same motor.

so M-B and the FIA (and the NACA and 15000-engines Wright) were .... Wrong ?
so there is no 'free' kinetic energy in the exhaust pulses/waves of an exhaust stream at 1 atmosphere mean pressure ?

yes of course the MGU-H generation is burdened by turbine efficiency limitations
yes the exhaust KE is used in 'tuned-length' exhaust systems (F1 is to some extent robbing Peter to pay Paul)

or could Audi be making their 'best' measurements when the ES is running on stored energy ?

[PlatinumZealot]

Those moveable vanes in front of compressor intake. A throttling system. Manipulating that throttling system will result in less turbo lag, faster turbo spinning, no need for a blow-off valve.

It's not really a throttle even though you could use it like one.

It's as it says on the tin. It's a set of guide vanes to "pre-spin" the air before it enters the fast spinning compressor blades. Think of it like a variable ramp.

If you use it like a throttle you could have a bad effect of unloading the compressor really fast and thta leads to severe overspeed. I think closing this must be only done in very special cases. Cases which I can't come up right now....

[PlatinumZealot]

What advantage do the vanes serve?

they enable airflow adjustment with lower losses than eg a butterfly throttle would
(eg for cruise an airliner has the IGVs deployed)

in most circumstances they are improving the efficiency of the compressor
so reducing the energy it requires - freeing more energy for electrical generation by the MGU-H

iirc these (variable geometry) vanes have only been allowed in F1 in the last 4 or 5 years ?

I don't think it is a throttle at all. Some old cars had throttle infront of the turbo but that was because they had carburettors and carbs couldn't work properly after the compressor.

[saviour stivala]

The exhaust system of any turbocharged ICE no matter how tuned will always have some back pressure to contend with. As the turbocharger turbine is always a pressure turbine unlike the Wright three exhaust turbine used, which were not of the pressure turbine type. The Audi electric supercharger eliminates the exhaust back pressure created by a turbocharger turbine. This turbocharger turbine caused back pressure has been proven by F1 power unites to cost upper of 25 bhp. By them being able to run the compressor in electric mode and with the exhaust bypassing the turbine.

[saviour stivala]

Those moveable vanes in front of compressor intake. A throttling system. Manipulating that throttling system will result in less turbo lag, faster turbo spinning, no need for a blow-off valve.

It's not really a throttle even though you could use it like one.

It's as it says on the tin. It's a set of guide vanes to "pre-spin" the air before it enters the fast spinning compressor blades. Think of it like a variable ramp.

If you use it like a throttle you could have a bad effect of unloading the compressor really fast and thta leads to severe overspeed. I think closing this must be only done in very special cases. Cases which I can't come up right now....

Respect your opinion about the ‘moveable vanes’ as used in F1, But your opinion does not change mine about their real use.

[chrisc90]

Interesting little snippets there.

[PlatinumZealot]

Those moveable vanes in front of compressor intake. A throttling system. Manipulating that throttling system will result in less turbo lag, faster turbo spinning, no need for a blow-off valve.

It's not really a throttle even though you could use it like one.

It's as it says on the tin. It's a set of guide vanes to "pre-spin" the air before it enters the fast spinning compressor blades. Think of it like a variable ramp.

If you use it like a throttle you could have a bad effect of unloading the compressor really fast and thta leads to severe overspeed. I think closing this must be only done in very special cases. Cases which I can't come up right now....

Respect your opinion about the ‘moveable vanes’ as used in F1, But your opinion does not change mine about their real use.

Synthesize some examples around your theory then.

[saviour stivala]

The reason the vanes are adjustable is the more closed they are, the higher the swirl, but of course the less flow, so they are open and close along with airflow requirement to not be a restriction. This adjustability can be as basic as a form of throttle, or boost, or even complex set-ups that read airflow and turbo rpm. They also tend to fully close (road car application) when the driver lifts the throttle, as much like putting your hand over a vacuum cleaner nozzle, preventing airflow to compressor gives it less work to do, which increase turbo rpm for any given turbine flow, making the turbo run higher rpm when the throttle is closed, reducing or eliminating turbo lag when the driver gets back on throttle. This system of restricting airflow to compressor might have been the main cause of the oil-burn previously.

[saviour stivala]

Must add. ‘’the system of reducing airflow to compressor could have been the cause of the oil-burn previously’’. One disadvantage of this system, or better say, one problem it will cause, is the vacuum created when vanes are closed or near closed which will greatly affect the compressor side bearing oil sealing capability.

[PlatinumZealot]

The reason the vanes are adjustable is the more closed they are, the higher the swirl, but of course the less flow, so they are open and close along with airflow requirement to not be a restriction. This adjustability can be as basic as a form of throttle, or boost, or even complex set-ups that read airflow and turbo rpm. They also tend to fully close (road car application) when the driver lifts the throttle, as much like putting your hand over a vacuum cleaner nozzle, preventing airflow to compressor gives it less work to do, which increase turbo rpm for any given turbine flow, making the turbo run higher rpm when the throttle is closed, reducing or eliminating turbo lag when the driver gets back on throttle. This system of restricting airflow to compressor might have been the main cause of the oil-burn previously.

It's primarily for efficiency by reducing inlet losses. As you say swirl.

Closing the vanes actually wont reduce turbolag. It would increase it.. Because the lag is measured in rise in boost pressure. No air.. No boost pressure.

The same overspeed example i gave you can actually be problem in F1 so I wanted to see if you had any examples of why you want to rapidly unload the compressor.

I thought you would say it is used to prevent surges during braking or something like that.

[saviour stivala]

Closing the movable vanes when driver lifts throttle will increase turbo rpm for a given turbine exhaust flow because with no airflow the compressor have less work to do, when driver returns on throttle the turbo higher rpm will eliminate turbo lag.