Further to that, it is possible the turbomachinery runs slower as engine speed increases above 10,500 rpm (to maintain constant mass flow and therefore constant AFR). This will depend on which part of the compressor map is being used although the speed lines are usually near horizontal in the peak efficiency region.Mudflap wrote: ↑18 Sep 2019, 00:32. . . As a side note, in turbomachinery where unbalance forces are significant (the main source of bearing loads) there tends to be a more pronounced friction increase with speed since unbalance forces increase with the square of angular velocity. This is definitely not the case with reciprocating engines where loads are dominating by firing, gears, springs etc. and inertial loads are relatively small.
The obvious consequence is a further reduction in the rate of increase of total frictional losses with increasing engine speed.