Renault Power Unit Hardware & Software

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
henry
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Re: Renault Power Unit Hardware & Software

Post by henry » Fri Jan 11, 2019 9:49 am

PlatinumZealot wrote:
Thu Jan 10, 2019 11:05 pm
henry wrote:
Thu Jan 10, 2019 8:18 pm
PlatinumZealot wrote:
Thu Jan 10, 2019 7:55 pm
Define blowdown...

I have only seen this word in very old PV graphs... for turbocharged 2 strokes? But never saw a good explanation. Granted, I have not really tried researching that term too much.
Fortunately there’s a whole thread on the topic

viewtopic.php?f=4&t=20312
Nope! I remember that thread! I won't re-enter!

There was no clear answer.. I have a Pressure-Volume graph with blow-down featured on it, which I might post if anyone is interested.. and some other very old references. But I would like a clear definition for everyone to be able to join the discussion. It's mostly the old-heads you hear with this blow-down term.
It seems unlikely that you would see much on a Pressure-Volume graph since blowdown is concerned with the kinetic energy of the exhaust stream outside the cylinder.

It’s in old references because it was pursued in an effort to make high performance aircraft piston engines more efficient, extracting work from the exhaust stream while not reducing the amount of work on the pistons. This was called compounding. The advent of turbines stopped pursuit of these routes to aero engine efficiency.

And now we have F1 power units in which compounding is mandated and, not surprisingly, the technique appears relevant again as part of mixed mode operation of the turbines.

This is only theory since the PU manufacturers don’t say much about how their units work at all. Honda are an exception but haven’t said anything on this.

You may, of course, not find this convincing. That’s your prerogative. But please don’t shout if you respond.
Fortune favours the prepared; she has no favourites and takes no sides.
Truth is confirmed by inspection and delay; falsehood by haste and uncertainty : Tacitus

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Re: Renault Power Unit Hardware & Software

Post by Tommy Cookers » Fri Jan 11, 2019 10:56 am

well PZ I would like to see your PV diagram .... and/but broadly .....

the first supercharger was not a (mechanically-driven) supercharger
it was a turbocharger .....the Rateau of c.1907 ...... think about this .....

presented as the answer to the altitude problem of aircraft
(remember engines had atmospheric inlet valves - being worked by suction, they were very sensitive to altitude)

but aircraft took up mechanically driven supercharging instead - that's how it got into car racing

the turbocharger clearly needed so-called back-pressure to work
and most people missed or didn't believe that there's recoverable work from the exhaust without so-called back pressure

that's what the so-called blowdown turbine is - it's a power recovery turbine feeding power to the crankshaft
because the turbine isn't driving a supercharger it doesn't load the exhaust enough to raise the mean exhaust pressure
(and of course the exhaust system design doesn't allow exhaust pulses to propagate to cylinders in the scavenge phase)
it runs only on the kinetic energy in the pulses - the supercharger is independent and driven mechanically by the crankshaft
this blowdown PRT gives free energy - roughly 10% added to crankshaft power

only 1 such engine was produced in quantity - the Wright 'Turbocompound'
it semi-revolutionised international flight by allowing increased range and weight
though direct use of piston engine exhaust 'jet effect' was simpler and better used at higher altitudes and speeds

modern turbocharged engines tend to use exhaust pulses ie the compressors are partly driven by blowdown power
the F1 engines do this - the 3 headers/1 runner per bank preserve the pulses as blowdown doesn't overlap any scavenge
older engines having commonised exhaust flows had high mean exhaust pressure - this arrangement was called pressure turbine
Last edited by Tommy Cookers on Fri Jan 11, 2019 1:52 pm, edited 2 times in total.

dren
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Re: Renault Power Unit Hardware & Software

Post by dren » Fri Jan 11, 2019 12:33 pm

It's like sticking a wheel in a stream of water to drive a shaft. It uses the velocity of the mass flow for power. I guess you could call it a kinetic energy turbine.
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Brake Horse Power
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Re: Renault Power Unit Hardware & Software

Post by Brake Horse Power » Fri Jan 11, 2019 7:54 pm

henry wrote:
Wed Jan 09, 2019 10:37 am
Tommy Cookers wrote:
Tue Jan 08, 2019 8:49 pm
Brake Horse Power wrote:
Tue Jan 08, 2019 8:07 pm
.... wastegate open ......The exhaust pulsation can maybe also be better utilisied as in a NA engine...
if the wastegate is open the mean exhaust pressure is maybe 1.05 bar
if the wastegate is closed the mean exhaust pressure is maybe 4.05 bar

even with an active turbine surely the 4.05 bar stream has bigger pulse reflections available than the 1.05 bar stream does ?
what did the 80s F1 turbo engines do ? (though they might have had no use for the benefit as they didn't recover power)

ok the 4.05 bar stream the pulse energy has less energy relative to the steady flow energy (than does 1.05 bar stream)
because less of the 4.05 stream's flow will be choked as the gas acceleration will be less due to the higher density
So the wastegate opening impacts 3 areas of performance?

It changes the tuned pressure wave reflections in the exhaust system that aid cylinder filling (I believe this is what you are referring to). ICE performance goes down?
What is 'funny' is that instead of a pressure pulse reflecting on a turbine wheel, with the waste gate open the pressure pulse ends up in outside air. Returning a low pressure energy puls instead of a high pressure. So beside affecting mean exhaust pressure, it actually changes the way how the exhaust works.

Edit: If you have an extremely high mean exhaust pressure, you would also need an extremely high intake air pressure at the same time in order to properly scavenge the cylinder. Otherwise during valve overlap you will have blowback. (Alternatively: If there is no valve overlap you don't have a full charge of fresh air in the cylinder. = Less power so that doesn't make sense)

So maybe you could say the the mean exhaust pressure needs to be lowered with the waste gate in order for the compressor side to do it's work properly, when the compressor is not giving full pressure (at lower rpm)

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Re: Renault Power Unit Hardware & Software

Post by PlatinumZealot » Sun Jan 13, 2019 3:16 am

henry wrote:
Fri Jan 11, 2019 9:49 am
PlatinumZealot wrote:
Thu Jan 10, 2019 11:05 pm
henry wrote:
Thu Jan 10, 2019 8:18 pm


Fortunately there’s a whole thread on the topic

viewtopic.php?f=4&t=20312
Nope! I remember that thread! I won't re-enter!

There was no clear answer.. I have a Pressure-Volume graph with blow-down featured on it, which I might post if anyone is interested.. and some other very old references. But I would like a clear definition for everyone to be able to join the discussion. It's mostly the old-heads you hear with this blow-down term.
It seems unlikely that you would see much on a Pressure-Volume graph since blowdown is concerned with the kinetic energy of the exhaust stream outside the cylinder.

It’s in old references because it was pursued in an effort to make high performance aircraft piston engines more efficient, extracting work from the exhaust stream while not reducing the amount of work on the pistons. This was called compounding. The advent of turbines stopped pursuit of these routes to aero engine efficiency.

And now we have F1 power units in which compounding is mandated and, not surprisingly, the technique appears relevant again as part of mixed mode operation of the turbines.

This is only theory since the PU manufacturers don’t say much about how their units work at all. Honda are an exception but haven’t said anything on this.

You may, of course, not find this convincing. That’s your prerogative. But please don’t shout if you respond.
Hmm.. didn't say I don't know what it is. I was in that discussion too after all. But I feel the term just needs more clearing up so everyone is on one page without having to be a hardcore engine cycle-researcher.

Here is one such P-V graph.

Image

Got the definition...simple and clean...
Blowdown is the amount of time/distance/degrees between
exhaust port opening and transfer port opening.
The absolute most accurate description of blowdown would
be... the amount of TIME between the exhaust and transfer
port openings. This "measurement" would of course only be
accurate at one rpm, so blowdown is commonly referred to in
degrees of crank rotation.
Also on page 9 here...blow-down loss.

http://www.iitg.ac.in/scifac/qip/public ... cycles.pdf

@ Tommy cookers..

Now that I have reconciled the term with what I know already.. the blowdown loss is the pulse of exhaust gasses at the "tail" of the power stroke. Basically only pulse tuned manifolds can utilize it. I also read that by tuning the shock-wave from other cylinders can push back any fresh intake air from escaping during overlap. It still is a loss to utilizing all the energy from expansion!. but I guess if the pulses can be utilized otherwise...

Since I have to deal with giant slow speed 2 stroke diesels at work these days.. I have seen the term in old references.. The engines used to use pulse manifolds for blow-down effect. It was most effective to join 3 cylinders to a collector.. 4 cylinders or more per collector and the pulses would crash into each other (hence the advent of two scroll turbines if this is to be preserved) The blowdown tuned exhaust manifolds had to be short and tubular to preserve the pulses too. Nowadays the multiple cylinders engines minimize the number of turbochargers to save space and cost. So more than three cylinders are normally connected to one big constant pressure receiver (or log manifold as people call it). The cheaper log manifold also has less thermal variations too.. and lighter turbine wheels could be made to take advantage of the more constant conditions.

In the giant two stroke diesel world.. they say the log manifold is about 5% more efficient than the pulse tuned manifold because the more constant conditions allow a reduced exhaust overlap (blowdown loss) thus increase utilization of expansion, and the turbocharger parts can be lightened/optimized for the lower peak loads...

I am not sure how the log manifolds were used by mercedes and honda in Formula 1 but it seems that pulse-tuning is definitely prefered these days. I get what you are saying, when you say the pulse is "free-energy" from the momentum of the gas.. but it in this efficiency formula supposed this blowdown energy is better utilized in combustion chamber than through the turbocharger? (I think this is what Honda's Tanabe alludes to when he mentions ICE power versus MGUH power)...
"The true champions are also great men. They are capable of making difficult decisions, of admitting their mistakes and of pushing harder than before when they get up from a fall."

- Ferrari chairman Sergio Marchionne

Tommy Cookers
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Re: Renault Power Unit Hardware & Software

Post by Tommy Cookers » Sun Jan 13, 2019 7:44 pm

blowdown energy is 'by definition' energy that cannot be used by in the combustion chamber
because it's the amount of energy needed to blow down the cylinder to ambient pressure by the start of the scavenge stroke
that's why using it in further expander is getting energy for free

blowdown recovery occurs whether mean exhaust pressure is 1 bar or 4 bar
it's just that people wrongly assume there's no turbine-recoverable energy at 1 bar
ie that recovery can't occur without causing exhaust pressure to increase

best PU efficiency may be with turbine loading that raises mean exhaust pressure well above induction pressure

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Re: Renault Power Unit Hardware & Software

Post by gruntguru » Mon Jan 14, 2019 2:46 am

1. There is more blowdown energy available when manifold pressure is lower (eg 1 bar).
2. Only the first part of blowdown is "choked" (supersonic flow). Choked flow persists while the absolute pressure in the cylinder is greater than (roughly) double the exhaust port absolute pressure, so clearly the transition to subsonic flow will occur earlier when exhaust back pressure is higher. The important thing is that while the flow is choked, the flow does not change with changes in exhaust back pressure. Is is dependent however on valve opening, flow coefficient and cylinder pressure.
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bucker
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Re: Renault Power Unit Hardware & Software

Post by bucker » Tue Jan 15, 2019 12:08 pm

Everybody is talking about significant gains from Renault PU :D :D . Can we get some articles claiming that, and were we are with horses compared to Ferrari and Mercedes.

dfegan358
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Re: Renault Power Unit Hardware & Software

Post by dfegan358 » Tue Jan 15, 2019 12:19 pm

I am sure Renault are making gains with their power unit!

I would be surprised however if Ferrari and Mercedes weren’t matching those gains.

Will be very interesting to see the relative power unit performance.

Big claims from Renault regarding progress and Mercedes found extra power from energy recovery.

All quiet from Ferrari on engine development this winter so far.

I don’t think Renault will make much inroads to be honest against the top two in PU performance.

PhillipM
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Re: Renault Power Unit Hardware & Software

Post by PhillipM » Tue Jan 15, 2019 11:39 pm

Well, we know they have a good 20-30bhp straight away if their engine just matches Spec C, since both McL and Renault were running B spec motors last year.

PlatinumZealot
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Re: Renault Power Unit Hardware & Software

Post by PlatinumZealot » Wed Jan 16, 2019 12:07 am

dfegan358 wrote:
Tue Jan 15, 2019 12:19 pm
I am sure Renault are making gains with their power unit!

I would be surprised however if Ferrari and Mercedes weren’t matching those gains.

Will be very interesting to see the relative power unit performance.

Big claims from Renault regarding progress and Mercedes found extra power from energy recovery.

All quiet from Ferrari on engine development this winter so far.

I don’t think Renault will make much inroads to be honest against the top two in PU performance.
Wouldn't you say that Ferrari and Mercedes have hit the proverbial horsepower ceiling? The overall feeling was that Renault and Honda came closer, and the two leading engines seemed to be in a dead-lock. A sign of convergence.
"The true champions are also great men. They are capable of making difficult decisions, of admitting their mistakes and of pushing harder than before when they get up from a fall."

- Ferrari chairman Sergio Marchionne

Juzh
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Re: Renault Power Unit Hardware & Software

Post by Juzh » Wed Jan 16, 2019 9:38 am

PlatinumZealot wrote:
Wed Jan 16, 2019 12:07 am
dfegan358 wrote:
Tue Jan 15, 2019 12:19 pm
I am sure Renault are making gains with their power unit!

I would be surprised however if Ferrari and Mercedes weren’t matching those gains.

Will be very interesting to see the relative power unit performance.

Big claims from Renault regarding progress and Mercedes found extra power from energy recovery.

All quiet from Ferrari on engine development this winter so far.

I don’t think Renault will make much inroads to be honest against the top two in PU performance.
Wouldn't you say that Ferrari and Mercedes have hit the proverbial horsepower ceiling?
I don't believe that is the case at all. Remember ferrari upgrade in canada last year. There were even comments from abitebul how they didn't anticipate such perfromance gains from this formula, yet there they were, clear as day.

As for the merc vs ferrari. In general ferrari later in the year definitely had higher straight line speeds than mercedes, by quite a bit, though mercedes were much faster in the corners so it's pretty hard to judge them. At times the difference was too big in ferrari's favour to be all down to the engine (10+ kmh advantage), so they really had to have a slippery car.

Blackout
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Re: Renault Power Unit Hardware & Software

Post by Blackout » Wed Jan 16, 2019 2:53 pm

According to this https://motorsport.nextgen-auto.com/Les ... 33854.html
Mercedes peak power = Ferrari = 1030 hp in qualy and 980 hp (race - average)
Renault 990 hp and 950 race.
Honda 950 hp and 930 race
But I dont know his sources.
Abiteboul said Renault lacks around 50 hp (Q) and that Honda is around 30hp behind Renault.

PlatinumZealot
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Re: Renault Power Unit Hardware & Software

Post by PlatinumZealot » Thu Jan 17, 2019 1:07 am

They said Honda surpassed Renault.
Mercedes has not announced their new thermal efficiency achievement this year.. so I have a feeling it barely moved.
I won't be surprised if Renault and Honda are within 25hp on the second set of engines.
"The true champions are also great men. They are capable of making difficult decisions, of admitting their mistakes and of pushing harder than before when they get up from a fall."

- Ferrari chairman Sergio Marchionne

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Re: Renault Power Unit Hardware & Software

Post by djos » Thu Jan 17, 2019 1:42 am

PlatinumZealot wrote:
Thu Jan 17, 2019 1:07 am
They said Honda surpassed Renault.
Mercedes has not announced their new thermal efficiency achievement this year.. so I have a feeling it barely moved.
I won't be surprised if Renault and Honda are within 25hp on the second set of engines.
I'd be very surprised if there's any big gains left for Merc and Ferrari to find - I think they've run well into the law of diminishing returns. From here's it's all going to be very very incremental. From what I've read, Thermal efficiencies in the 60% range are theoretically possible but considered unlikely to be practically achievable - especially for F1 teams with all the material and other limitations forced by the rules.
The impossible often has a kind of integrity which the merely improbable lacks.