Will we still hear the external wastegates venting in 2022?

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
saviour stivala
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Re: Will we still hear the external wastegates venting in 2022?

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''WGO (waste-gate open) back pressure is the same''. No it is not the same.

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Re: Will we still hear the external wastegates venting in 2022?

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The formula 1 turbo turbine is ‘a pressure turbine’. Without back pressure (Collector pressure) you have no boost. Meaning the exhaust collector pipe must be above atmospheric pressure for the turbo to produce boost. When the formula 1 waste-gate is fully open, the collector pipe is at very near atmospheric pressure. Which in turn it means no power recovery by the turbine is possible. The turbine being a pressure turbine is because from the point of exhaust gas entry into the turbine housing to the point of the exhaust gas hitting the turbine blades, the exhaust gas goes through a nozzle (a passage that narrows).

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Re: Will we still hear the external wastegates venting in 2022?

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It is not as simple as that. The pressure in the exhaust runners is far from steady. There are large pressure spikes which travel down the runners even when the average pressure is atmospheric. These pulses will be high enough to force their way through the turbine and perform some ueseful work even though the engine sees essentially atmospheric pressure in the eaxhaust header.

The same conditions existed in the Wright Turbo Compound engine which extracted useful energy from the exhaust without adding any pumping work to the piston engine. F1 engines have the appropriate exhaust manifolding to do this and careful design of the wastegate and its plumbing would enable some energy to be extracted from the turbine during electric supercharger mode while still relieving the piston engine from exhaust pumping work - increasing power at the crankshaft.
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saviour stivala
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Re: Will we still hear the external wastegates venting in 2022?

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The wright turbo compounding used a ‘blow-down’ turbine and not a ‘pressure turbine’.
The formula 1 turbo uses a pressure turbine, as such unless collector pressure is above atmospheric pressure, no recovery by the turbine is possible.

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yelistener
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Re: Will we still hear the external wastegates venting in 2022?

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Damn, they're going back to 2014-2015 style on this? Say byebye to the wastegate open sound then. :(

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Re: Will we still hear the external wastegates venting in 2022?

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saviour stivala wrote:
Wed Feb 23, 2022 9:08 am
The wright turbo compounding used a ‘blow-down’ turbine and not a ‘pressure turbine’.
The formula 1 turbo uses a pressure turbine .....
those hundreds of millions of turbocharged road vehicles that have been built ......
what type of turbine do they have ?


so-called 'back pressure' - on this site I have been assured by owners that 'forward pressure' operation is normal eg ......
road (Porsche) boost gauge readings are mostly/often higher than exhaust pressure gauge readings
similarly with low boost race cars eg Indy cars over the last c.50 years

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Re: Will we still hear the external wastegates venting in 2022?

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Aren't they all mixed flow turbines? They work with both pressure and kinetic impulse. The casing jets/nozzles air into the turbine wheel, exchanging pressure energy for kinetic energy, the wheel once again jets/nozzles air into the exhaust. Once again trading pressure energy for kinetic energy.

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saviour stivala
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Re: Will we still hear the external wastegates venting in 2022?

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The blowdown turbine is an ‘impulse turbine, were the gases are conveyed to the turbine wheel through separate Siamese pipes.
A pressure turbine as used by the F1 turbo, the gases of all cylinders are conveyed to the turbine wheel through a collector pipe, with two possible paths. ether through a waste-gate or through the turbine wheel.

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Re: Will we still hear the external wastegates venting in 2022?

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godlameroso wrote:
Wed Feb 23, 2022 7:12 pm
Aren't they all mixed flow turbines? They work with both pressure and kinetic impulse. The casing jets/nozzles air into the turbine wheel, exchanging pressure energy for kinetic energy, the wheel once again jets/nozzles air into the exhaust. Once again trading pressure energy for kinetic energy.

https://www.energy.gov/sites/default/fi ... k=Wcwy8dAU
Correct. The whole point of divided turbine housings is to provide separate nozzles so that no more than 3 even-firing cylinders are connected to each nozzle. (The Wright Turbo Compound had two cylinders connected to each nozzle and three nozzles per turbine.) This allows the turbine to harness the energy contained in blowdown pressure pulses which are higher than the average exhaust pressure.

This means that any turbocharger can be operated as either a pressure turbine, a blowdown turbine or a mix. Even the Wright TC could have been operated as a mixed turbine by simply reducing the nozzle size to the point where average exhaust pressure is above atmospheric. This would have increased the turbine power but at a cost to crankshaft power due to increased exhaust stroke pumping energy.
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Re: Will we still hear the external wastegates venting in 2022?

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gruntguru wrote:
Fri Feb 25, 2022 12:49 am
godlameroso wrote:
Wed Feb 23, 2022 7:12 pm
Aren't they all mixed flow turbines? They work with both pressure and kinetic impulse. The casing jets/nozzles air into the turbine wheel, exchanging pressure energy for kinetic energy, the wheel once again jets/nozzles air into the exhaust. Once again trading pressure energy for kinetic energy.

https://www.energy.gov/sites/default/fi ... k=Wcwy8dAU
Correct. The whole point of divided turbine housings is to provide separate nozzles so that no more than 3 even-firing cylinders are connected to each nozzle. (The Wright Turbo Compound had two cylinders connected to each nozzle and three nozzles per turbine.) This allows the turbine to harness the energy contained in blowdown pressure pulses which are higher than the average exhaust pressure.

This means that any turbocharger can be operated as either a pressure turbine, a blowdown turbine or a mix. Even the Wright TC could have been operated as a mixed turbine by simply reducing the nozzle size to the point where average exhaust pressure is above atmospheric. This would have increased the turbine power but at a cost to crankshaft power due to increased exhaust stroke pumping energy.
I find the relationship between all those variables fascinating. Once you understand the relationship everything becomes damn near intuitive.
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saviour stivala
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Re: Will we still hear the external wastegates venting in 2022?

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The mixed-flow type of turbine design used on road going car engines exhaust turbochargers combines the blade-tip angle of an axial turbine and a radial turbine (mixed-flow turbine). As such the mixed-flow turbine efficiency is improved over that of the axial turbine or the radial turbine. But contrary to the believe/attempts at pushing it (the mixed-flow turbine) out as a ‘blow-down’ energy harnessing turbine, it is not. The ‘mixed-flow’ turbine as used in road going engines exhaust turbochargers is still of the ‘pressure turbine’ type. And as such it is still feed by an exhaust collector pressure, and unless that collector pressure is above atmospheric still no recovery is possible by the ‘mixed-flow’ turbine. This unlike the ‘blow-down’ type of turbine, which harnesses ‘blow-down’ energy ‘pressure-pulses’ piped to the turbine without adding pressure to the exhaust of any cylinder that is executing its exhaust stroke. It is exactly because of the exhaust collector pipe need to be above atmospheric pressure and the ability of the waste-gate to eliminate this collector pipe pressure that extra power is extracted out of the formula one engine. A ‘blow-down’ turbine harnessing pressure pulses cannot make use of a ‘waste-gate’ to eliminate higher than atmospheric pressure in the exhaust piping leading to the turbine housing, because there is non.

saviour stivala
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Re: Will we still hear the external wastegates venting in 2022?

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The exhaust driven turbocharger turbine as used for road going engines can be designed to run in any one of the four configurations, namely axial-flow, radial-flow, mixed-flow pressure turbine or a blow-down pulse type of turbine. But the first three design types will still operate as a pressure type of turbine, and will not be able produce any boost by compressor unless the collector pressure is above atmospheric pressure. While the last, The blow-down pulse turbine will operate as a pulse turbine only. Increasing the manifold pressure by reducing nozzle size of the blow-down pulse type of turbine will render it a pressure turbine. The pressure turbine and the blow-down pulse turbine designs cannot be combined in one simply because one operates by exhaust gas pressure and the other operates by exhaust pulse velocity with no pressure.

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Re: Will we still hear the external wastegates venting in 2022?

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I accept the correct definition of a "mixed" flow turbine is the radial/axial blended design. I used the word "mixed" to describe a turbine which blends the harnessing of pressure and blowdown energy because @godlameroso used it.

That aside, you are incorrect to say that a turbine cannot operate as a combination of the pressure and pulse types.
Twin-scroll turbochargers are using both thermal and pulse (pressure wave) energy of the exhaust gas in order to obtain mechanical work to drive the intake air compressor.
From: https://x-engineer.org/twin-scroll-turbo/
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saviour stivala
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Re: Will we still hear the external wastegates venting in 2022?

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Of course a twin-scroll pressure turbine make use of exhaust pulses. As best as the design can to mitigate the effect of the ‘odd firing intervals’ dictated by a 90 degree V6 with three-pin crank. But my point was. What actually happens when the exhaust gases pressure is taken off the pressure turbine by the waste-gate fully open rendering the collector feeding said turbine at near atmospheric pressure. I say the pulses in collector will be of no use to the turbine, as they will be diverted ‘through the waste-gate’ from a point before the turbine by following the exhaust gases diversion and out to atmosphere through the waste-gate tail pipe. So yes, a twin scroll pressure turbine will make use of exhaust pulses, but only as long as the waste-gate is closed. And another thing. ‘a mixed flow turbine’. by means of design angle to the outer tip of the turbine wheel blades, is so called because it make use of flows of both the radial turbine as well as that of the axial flow turbine and nothing to do with exhaust pulses.

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Re: Will we still hear the external wastegates venting in 2022?

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saviour stivala wrote:
Wed Feb 23, 2022 7:50 pm
The blowdown turbine is an ‘impulse turbine, were the gases are conveyed to the turbine wheel through separate Siamese pipes.

A pressure turbine as used by the F1 turbo, the gases of all cylinders are conveyed to the turbine wheel through a collector pipe, with two possible paths. ether through a waste-gate or through the turbine wheel.
isn't that second sentence just .... wrong ?

F1 exhaust goes to the turbine via 2 separate 'collectors' - each reaching only a part of the wheel that the other doesn't
with only 3 cylinders (240 deg interval) per collector this is all that is needed for good blowdown working


and ....
https://ntrs.nasa.gov/api/citations/199 ... 082430.pdf is a good read
its V12 uses 2 cylinders (360 deg interval) per each of 6 collectors