2014-2020 Formula One 1.6l V6 turbo engine formula

[theloniousmonk]

Surely disconnecting the compressor from the MGU-H, could be done by having a bypass valve between the two ends of the compressor.

Assuming a bypass valve is legal.

[gruntguru]

Surprisingly not. The compressor will work very hard driving air around the bypass circuit and back into the inlet. What you are suggesting is best done by blocking the compressor inlet, creating zero mass flow and reduced air density in the compressor. A bypass would be required to keep air going into the engine which would of course become normally aspirated under these conditions.

[xpensive]

True grunts, that is also efficient to keep the compressor spinning at lift-off, I think Porsche pioneered this in CanAm.

[Facts Only]

Hi Facts Only. You have hinted that you have some knowledge of what the teams are actually doing. Can you shed any light on any of the other issues that we have been guessing at?
Examples:
- Manifold Absolute Pressure. (Renault mention 3.5 bar.)
- Thermal efficiency. (MB claim 40%+. We assume this is simultaneous ICE and MGUH.)
- Full power AFR. Opinions here vary from lambda 0.8 to 1.3
- Charge air temperature

My knowledge is more on the mechanical side but I can confirm that 3.5bar is about the average.

[Facts Only]

The MGUH can be either on the same shaft or running coaxially using a link with a ratio other than 1:1 but it must remain constant (i.e Fixed gear).

Thanks for this Facts Only.

The only thing I would dispute is the requirement that the MGUH is coaxial with the turbo's shaft assembly. It could be parallel or perpendicular or at any angle, so long as it is mechanically connected to the turbine's shaft with a fixed speed ratio. And may be clutched.

That said, I don't see any advantage to not having it co-axial - either between the turbine and compressor, as Mercedes and Ferrari have done, or ahead of teh compressor, as Renault have done.

Please see my original quote (cut down for space) I had written Axis and Coaxially too many times, it should have read:

"The MGUH can be either on the same shaft running coaxially using a link or running on a separate axis with a ratio other than 1:1 but it must remain constant (i.e Fixed gear)"

With regards to you second Point there are a couple of things that have been noted:

There is an interesting point in the rules which leaves room for running a geared MGUH that might give an advantage:

5.2.4 (Deleted for space) The rotational speed of the MGU-H may not exceed 125,000rpm.

There is no rule about the maxiumum speed the Turbocharger shaft (Comp/Turbine system) can run at so in theory the Compressor and Turbine wheels could run faster and than the MGUH be geared down to run withing the maximum limit.

Also the MGUH is a heavy unit, it could be mounted underneath the 'Turbocharger' on a gear drive to lower the centre of gravity if a manufacturer was stuggling to get close to the 200mm CoG Min height (Rule 5.4.2 The centre of gravity of the power unit may not lie less than 200mm above the reference plane).
Mounting the MGUH remotely could also shorten the Turbocharger unt and so allow the movement the CoG for/aft if required.
Lastly running upto 125k rpm presents massive shaft dynamics challenges, a remote MGUH could be used to overcome a number of issues.

[theloniousmonk]

Surprisingly not. The compressor will work very hard driving air around the bypass circuit and back into the inlet. What you are suggesting is best done by blocking the compressor inlet, creating zero mass flow and reduced air density in the compressor. A bypass would be required to keep air going into the engine which would of course become normally aspirated under these conditions.

Ok, with the way you mentioned, Would that have the same effect as decoupling the Compressor stage from the MGU-H via clutches?

[Tommy Cookers]

Surprisingly not. The compressor will work very hard driving air around the bypass circuit and back into the inlet. What you are suggesting is best done by blocking the compressor inlet, creating zero mass flow and reduced air density in the compressor. A bypass would be required to keep air going into the engine which would of course become normally aspirated under these conditions.

AFAIK
theo's 'bypass between the 2 ends of the compressor' is not used for practical reasons eg trapping/releasing a slug of high pressure air
though the compressor work would not be particularly high if the air is trapped, not backdriven into the atmosphere ?
the 'bypass' effect (even notionally allowing N/A operation) would normally include a throttle downstream of the compressor
ie the compressor bypass effect would be partial/variable, not on/off

systems (such as the Porsche 917 Can-Am that showed the world how a turbo engine could be made to work on a road course)
...... both throttle off the inlet (upstream) and provide a bypass (for the compressor), and have a throttle downstream ?
so the bypass air is trapped at rather low pressure

any time the usual (non-bypass) SI turbo car is not WOT the inlet is partially or majorly blocked blocked anyway
and surely the 'spooling-down' is greater then in the Porsche as above ?

millions of aircraft engines operated with partial throttling (auto or manual) even when obtaining full (permissible) power eg takeoff
this throttling was used to control boost eg to a constant despite variation of pressure with altitude
as the superchargers were mechanically driven compressor work cost engine power directly, so was rather important

with any of the real-world systems compressor power is not excessive ..... AFAIK

[hollus]

Here is a left field idea: Nowhere in the rules is it defined what is a compressor and what is a turbine other than by function and their position relative to other power unit components.
Nowhere does it say that they have to be monolithic, or that either of them has to have one an only one rotational speed. In particular no construction or part count is specified. Is the outer wall of the turbine part of the turbine? Does it rotate at the same speed as the rest? If the answers are 1) yes and 2) no, what is to limit the amount of different rotational speeds present in the turbine or in the compressor? Can one part meet the rules and another part, (possibly clutched?) act as a flywheel?

Here is another left field idea: There is this number of parts that have to have the same rotational speed at all times, but "may be clutched". The function of a clutch is, between other things, to allow things with different rotational speeds to come (slowly) to sync, and vice versa. So the rules seem to explicitly allow for a (presumably transient) difference in rotational speed. Does it say how quick this clutch response has to be? Can the clutch be designed to take several (tens?) seconds to achieve synchronous movement?

I don't really think that anything this outrageous is going on, but after the DDD (I would not trust the FIA to make a lifeboat seeing their definition of a hole), who knows? The rules around these components are surprisingly simple, considering the level of detail present elsewhere. This is a part of the rules that still hasn't grown to cover all loopslots.

[wuzak]

Here is a left field idea: Nowhere in the rules is it defined what is a compressor and what is a turbine other than by function and their position relative to other power unit components.
Nowhere does it say that they have to be monolithic, or that either of them has to have one an only one rotational speed. In particular no construction or part count is specified. Is the outer wall of the turbine part of the turbine? Does it rotate at the same speed as the rest? If the answers are 1) yes and 2) no, what is to limit the amount of different rotational speeds present in the turbine or in the compressor? Can one part meet the rules and another part, (possibly clutched?) act as a flywheel?

Turbine and compressor are well understood terms.

The rules define that there will be one of each, each will be single stage, and each must be connected by a shaft system so that the turbine (ie the wheel), the compressor (ie the impeller) and the rotating shaft components rotate at the same rpm, in the same direction around the same axis.

Which leaves the housings to be rotated. Which would make it difficult to connect the exhausts (for the turbine), or the inlet and discharge for the compressor.

I suppose you could make an intermediate housing which rotated, with the outside housing fixed. But then you're getting complicated. And if you vary thr relative speed between the intermediate housing and the turbine you fall foul of the rules disallowing variable geometry:

5.9.1 With the exception of devices needed for control of pressure charging systems, variable geometry exhaust systems are not permitted. No form of variable geometry turbine (VGT) or variable nozzle turbine (VNT) or any device to adjust the gas throat section at the inlet to the turbine wheel is permitted.

Here is another left field idea: There is this number of parts that have to have the same rotational speed at all times, but "may be clutched". The function of a clutch is, between other things, to allow things with different rotational speeds to come (slowly) to sync, and vice versa. So the rules seem to explicitly allow for a (presumably transient) difference in rotational speed. Does it say how quick this clutch response has to be? Can the clutch be designed to take several (tens?) seconds to achieve synchronous movement?

The clutch only relates to the connection of the MGUH and the turbine shaft. There is no mention of a clutch in the rules about the turbo itself.

I don't really think that anything this outrageous is going on, but after the DDD (I would not trust the FIA to make a lifeboat seeing their definition of a hole), who knows? The rules around these components are surprisingly simple, considering the level of detail present elsewhere. This is a part of the rules that still hasn't grown to cover all loopslots.

Again, the DDD was allowed because the holes were in the vertical plane, not because they called them "slots".

[langwadt]

I don't really think that anything this outrageous is going on, but after the DDD (I would not trust the FIA to make a lifeboat seeing their definition of a hole), who knows? The rules around these components are surprisingly simple, considering the level of detail present elsewhere. This is a part of the rules that still hasn't grown to cover all loopslots.

Again, the DDD was allowed because the holes were in the vertical plane, not because they called them "slots".

weren't the DDD loop hole that "no holes" were defined as you shouldn't be able to see through the floor?

[gruntguru]

Tommy.
Aircraft engines were usually throttled upstream of the compressor for two reasons. Firstly, downstream throttling can drive the compressor into surge. 2. Throttling upstream reduces compressor power requirement compared to both WOT and downstream throttling scenarios.

Operating the compressor with a large bypass ie PR = 1.0 will drive the compressor into the choke region which is an area of low efficiency and high shaft power.

[wuzak]

Tommy.
Aircraft engines were usually throttled upstream of the compressor for two reasons. Firstly, downstream throttling can drive the compressor into surge. 2. Throttling upstream reduces compressor power requirement compared to both WOT and downstream throttling scenarios.

Operating the compressor with a large bypass ie PR = 1.0 will drive the compressor into the choke region which is an area of low efficiency and high shaft power.

And, of course, when a compressor is designed to give the maximum permissible boost at altitude it would produce too much boost for the engine at sea and low level, either because of detonation or that simply the engine isn't strong enough.

[wuzak]

I don't really think that anything this outrageous is going on, but after the DDD (I would not trust the FIA to make a lifeboat seeing their definition of a hole), who knows? The rules around these components are surprisingly simple, considering the level of detail present elsewhere. This is a part of the rules that still hasn't grown to cover all loopslots.

Again, the DDD was allowed because the holes were in the vertical plane, not because they called them "slots".

weren't the DDD loop hole that "no holes" were defined as you shouldn't be able to see through the floor?

I think that's right - the rules required no holes visible from below. The holes/slots/ducts that were used by the DDD teams were in teh vertical plane, so could not be seen from below.

[strad]

they cut little slits from the edge of the hole to the edge of the floor and suddenly they were not holes...I have apicture around here somewhere.

[Dragonfly]

Guys, the DDD has little in common with the engines.
And I think that the turbo rules are quite strict in defining what it must be.