Renault Power Unit Hardware & Software

[lio007]

F1 season is no write-off for Renault

Unfortunately it seems they still haven't understood their reliability issues, I hope they will do soon.

[Edis]

From a purely turbo point of view I would agree. But the MGU-H is driven by the turbine also.

So we have two loads applied to the turbine Compressor and MGU-H

Power generation from the MGU-H is unlimited in the regulations. Boost is unlimited in the regulations, but is effectively limited by the fuel flow at about 2.75 Bar and mass air flow <1500kg/hr. As power is a function of force over distance and in the case of a generator torque applied over rotational speed, we can either apply high torque to the turbine at a lower speed or low torque at a higher speed. There will be a compromise of where in the scale of MGU-H tq/rpm gives the least backpressure to MGU-H benefit.

My thinking is, the work done by the turbine should favour the unlimited output-MGU-H. The turbine can have a finite amount of load applied before losses from increased back pressure exceed the gains from MGU-H.

Could the Turbine be sized where it makes up to 125k rpm at 7krpm engine speed or even at part throttle. In normal circumstances the compressor will surge, but if we bleed off excess mass air flow we could prevent surge. Yes there will still be load applied to the turbine by this work done, but there may be a balance to be had where total load applied to the turbine is less than the gains from MGU-H generation.

I am just theorising here and the 125k rpm may not be attainable, but I believe there will be a balance to be had, which will be forever changing with load and engine speed, where MGU-H power might take priority over compressor function and in the case of too much boost, then that could be bled off in order to prioritise MGU-H function?

You have misunderstood how turbines perform. It isn't turbine speed which cause the expansion ratio to increase (which is what you refer to as backpressure), but exhaust flow. Increase the exhaust flow and the expansion ratio will increase for any given turbine, and this is not really dependent on turbine speed. A turbine behaves similar to a nozzle, the more gas you try to push through the greater the pressure on the inlet side. Want to blow more gas without the increased inlet pressure - get a bigger nozzle.

Turbine efficiency is however dependent on turbine speed, or more specifically the blade to gas speed ratio. In other words, if you operate with a low amount of "backpressure", the gas velocity in the nozzle will be low and as a result the turbine speed should be low too. Of course, the amount of work that can be extracted from the exhaust gas by the turbine is dependent on the expansion ratio, so the more backpressure the engine can handle, the more power can be provided by the turbine.

If you bleed charge air you're wasting turbine power that could drive the generator instead.

[Wayne DR]

http://www.motorsport.com/f1/news/renau ... a/?v=2&s=1

Renault to trail new parts in 4th PU during FP1 and FP2, and then decide weather to take the 5th PU and incur grid penalties...

[PlatinumZealot]

Since replacing major ICE components is not allowed, and Honda is trying the upgrade on a used engine, it is fair to say Honda is using their first tokens on an ERS component?

[Vortex37]

From a purely turbo point of view I would agree. But the MGU-H is driven by the turbine also.

So we have two loads applied to the turbine Compressor and MGU-H

Power generation from the MGU-H is unlimited in the regulations. Boost is unlimited in the regulations, but is effectively limited by the fuel flow at about 2.75 Bar and mass air flow <1500kg/hr. As power is a function of force over distance and in the case of a generator torque applied over rotational speed, we can either apply high torque to the turbine at a lower speed or low torque at a higher speed. There will be a compromise of where in the scale of MGU-H tq/rpm gives the least backpressure to MGU-H benefit.

My thinking is, the work done by the turbine should favour the unlimited output-MGU-H. The turbine can have a finite amount of load applied before losses from increased back pressure exceed the gains from MGU-H.

Could the Turbine be sized where it makes up to 125k rpm at 7krpm engine speed or even at part throttle. In normal circumstances the compressor will surge, but if we bleed off excess mass air flow we could prevent surge. Yes there will still be load applied to the turbine by this work done, but there may be a balance to be had where total load applied to the turbine is less than the gains from MGU-H generation.

I am just theorising here and the 125k rpm may not be attainable, but I believe there will be a balance to be had, which will be forever changing with load and engine speed, where MGU-H power might take priority over compressor function and in the case of too much boost, then that could be bled off in order to prioritise MGU-H function?

You have misunderstood how turbines perform. It isn't turbine speed which cause the expansion ratio to increase (which is what you refer to as backpressure), but exhaust flow. Increase the exhaust flow and the expansion ratio will increase for any given turbine, and this is not really dependent on turbine speed. A turbine behaves similar to a nozzle, the more gas you try to push through the greater the pressure on the inlet side. Want to blow more gas without the increased inlet pressure - get a bigger nozzle.

Turbine efficiency is however dependent on turbine speed, or more specifically the blade to gas speed ratio. In other words, if you operate with a low amount of "backpressure", the gas velocity in the nozzle will be low and as a result the turbine speed should be low too. Of course, the amount of work that can be extracted from the exhaust gas by the turbine is dependent on the expansion ratio, so the more backpressure the engine can handle, the more power can be provided by the turbine.

If you bleed charge air you're wasting turbine power that could drive the generator instead.

Haven't you entirely missed the thermal part of the equation. For illustration, use appropriate part of formula.

These engines are fuel limited and not airflow limited. PU's are having their cylinders cut during lift and coast and deceleration. So the the thermal part of the equation will change rapidly.

[FW17]

At the tail end of last year Red Bull recruited – and paid – former Ilmor boss and engine design legend Mario Illien in an attempt to help Renault Sport make progress with its thus-far disappointing hybrid turbo V6. It would be fair to say that it has not been a straightforward integration; a lot of pride is at stake, as can be imagined. Renault Sport is a multiple world championship-winning engine supplier, Illien used to design the Mercedes-badged motors it was competing against in the back of the McLarens. There has been a very definite subtext of ‘we don’t need help in solving this problem’.

Illien meanwhile is convinced that a major part of the power unit’s shortfall lies in its combustion chamber. He has designed a single cylinder prototype that he believes would be the basis for a much improved performance. Renault Sport meanwhile has been pursuing its own development programme, the early dyno results of which are reportedly not as good as had been hoped. In the space between the last race and this one the Illien prototype was finally tested. If the results of this were deemed suitably encouraging, the full V6 version could be running in a matter of months. Red Bull would like it to be towards the end of this year, Renault Sport thinks the beginning of next could be more realistic.


-- Mark Hughes

[djos]

Wow, just goes to show how badly Renault fk'd up!

No wonder RedBull is so steamed up!

[Thunder]

Well when a Renault PU goes, it goes with style at least.

[rapha-78]

Honestly ocaviosa what's the point of disturbing F1 fans who just talk to each other about their passion ??? WTF ?

[gandharva]

Honestly ocaviosa what's the point of disturbing F1 fans who just talk to each other about their passion ??? WTF ?

This is probably a bot. So report and ignore until moderation/admins will take care of it.

[peterg]

Renault decide not to adopt Ilmor prototype?

http://www.motorsport.com/f1/news/renau ... pe-option/?

[domh245]

I think I've stumbled across Renault's problem, their choice of material just doesn't stand up to the job!

http://www.telegraph.co.uk/news/weather ... twave.html

NB: This post is not meant to be taken seriously! No Butthurt about Renault Sport F1 and Renault (road cars) being completely different things. Ta

[djos]

Renault decide not to adopt Ilmor prototype?

http://www.motorsport.com/f1/news/renau ... pe-option/?

Sounds like like they are too proud to use Mario's design, as if they didn't have enough egg on their faces already!

[Cold Fussion]

Could you perhaps leave such baseless statements for the general section of the forums and not pollute the technical suggestions as well?

[djos]

Could you perhaps leave such baseless statements for the general section of the forums and not pollute the technical suggestions as well?

So prove me wrong? Calling my assessment of the situation "baseless" without providing evidence to show that is the case and down-voting my comment is frankly pure hypocrisy!

I used the phrase "sounds like"; that is clearly me stating an opinion and not claiming it is a certifiable fact unlike yourself who clearly professes to have inside info!