"Dan Thomas" wrote

The turbine section drives the compressor, and extracts about 75%
of the energy from the gas flow in doing it. The remaining velocity
and pressure is what drives the engine forward. If I was to say where
the pressure is concentrated, I'd have to say it's against the
compressor disks.


Thanks for a truly informative post, Dan. A couple of questions:

1. Do you have a rough idea of the ratio of _axial_force_ on the compressor
disks vs. the turbine disks? Is the (backward) force on the turbine about 75%
of the (forward) force on the compressor, for instance?


Turboprop, turbofan and turboshaft engines have more turbine
stages to remove almost all the remaining energy and use it to drive a
fan or prop or helicopter transmission. In a high-bypass turbofan as
used on newer airliners, the fan produces most of the thrust. Four or
more times as much air goes around the engine as goes through it.


2. So, does this mean that in a turbofan engine the thrust really is indeed
mostly transmitted through the 10K+RPM spindle bearings? And are those
rolling-element bearings, or do they use some clever fluid-dynamical bearings in
modern engines?

-- Tony Prentakis