pgfpro wrote:...........at lower rpm range there will be opportunity to make more electricity on the turbo's generator due to the higher engine delta pressure. As the turbo's generator puts more load on the turbine this will create more back pressure.
the unprecedented new rules dictate reducing the air delivery per rev (charge) as the rpm increases beyond 10500
running with a rpm-varying electrical load from the GUH onto the turbine would slow the turbo and raise the exhaust pressure ('back pressure') above the turbine, both effects contribute to the required reduction in charge
ideally this load variation would maintain a relatively constant boost with rpm rise, the charge being largely managed by increasing back pressure governed by electrical load
(relatively constant boost makes best use of the piston expansion ratio)
(there is no need for wastegating ?)
the rather high back pressure will somewhat reduce the large pressure losses (pre-turbine) that occur even in a turbo engine
ie the turbine will use some exhaust energy unavailable at low back pressure
(these are losses caused by the near-unrestricted expansion of gas on release from the cylinders)
so generating some genuinely free electrical power for direct (immediate) use by the MUK ie some electric compounding
this potentially allows nominally full-time e compounding (is there any limit apart from the 120KW electrical power limit ?)
any practical approach requires a small rpm range ie full use of the standard gearbox (and some margin for short-shifting)
the small rpm range is suited to the usual fixed geometry tuned length induction & exhaust systems
with this approach the gearbox rules enable the driver to run electrically or not, 'non-actively' just by gear selection
(eg run full rpm range accelerating, then run high gear lower than full range rpm on straight)
we could design '12k' or '14k' engines, ie design for 11100 - 13000 rpm normal range or to 12900 - 15000 rpm normal range
(the 12k engine needs higher boost/turbocharging capacity, and has a lower piston CR/ER but also lower frictional losses)
the turbine must have capacity to drive the electrical load simultaneously
the electrical loading could easily lower the boost with rpm rise (by slowing the turbo), but this is to be minimised
(to maximise expansion in the cylinder at all rpm)
IMO what's not to like ?