the turbo rpm is continuously subject to the action of the MGU-H (because it's a synchronous machine)saviour stivala wrote: ↑17 Sep 2022, 14:31Closing 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.
The turbo rpm is not constantly controlled by the MGU-H. one example is when the driver goes off throttle. When the driver gets back on throttle yes, but the higher the turbo rpm is when driver goes off throttle the faster the MGU-H can spin-up the turbo when the driver returns on throttle.Tommy Cookers wrote: ↑17 Sep 2022, 17:58the turbo rpm is constantly controlled by the activity of the MGU-H (because it's a synchronous machine)saviour stivala wrote: ↑17 Sep 2022, 14:31Closing 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.
we have seen (Honda) bench runs showing that pre-corner the MGU-H pulls down the rpm getting a burst of generation
now everybody's talking about 'closing' the vanes - but the vanes don't close to restrict the flow
they vary the airstream's angle (eg with compressor rpm) to control angle of attack at the compressor blades
the angle can be eg for max compressor output - or some lesser angles reducing the output and load as required
reducing output and load in better proportion ie more efficiently than traditional things we normally call throttles
afaik until recently only fixed geometry was allowed .. (contrarily another thread says VGVs were allowed from 2014)
maybe the rules were then amended to enable elimination of the oil burn issue
now talk of 'iris throttles' (reducing compressor load power when reduced output is required) - as in a few WW2 planes
and the V16 BRM theoretically had the same concept - then called 'vortex throttling'
isn't it all the same thing ? (and rather new to F1 followers)
nosaviour stivala wrote: ↑17 Sep 2022, 20:39The turbo rpm is not constantly controlled by the MGU-H. one example is when the driver goes off throttle. When the driver gets back on throttle yes, but the higher the turbo rpm is when driver goes off throttle the faster the MGU-H can spin-up the turbo when the driver returns on throttle.Tommy Cookers wrote: ↑17 Sep 2022, 17:58the turbo rpm is constantly controlled by the activity of the MGU-H (because it's a synchronous machine)saviour stivala wrote: ↑17 Sep 2022, 14:31Closing 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.
we have seen (Honda) bench runs showing that pre-corner the MGU-H pulls down the rpm getting a burst of generation
that of course is entirely possible if the H machine has no other instructionsaviour stivala wrote: ↑18 Sep 2022, 14:46.. When driver goes of throttle the ‘’H’’ is doing no work on or by the turbo shaft. It is just getting a ride on the turbo shaft...
You got it back to front. Non-rotating inlet flow will give best efficiency at only one point (or line of points) on the map. Movable vanes will give best efficiency at every point on the map and will NEVER be detrimental.saviour stivala wrote: ↑18 Sep 2022, 07:49‘’Swirl caused by angling the movable vanes will actually only improve efficiency at only one point on the map. Generally the effects are detrimental to the efficiency and linear flow is desirable.’’