brooksjg, sorry but that's just not the case. A high bypass engine will of course have alot of air going through the fan and ash here is unlikely to do anything other than abrade the leading edges of each fan blade. But my point is that even a large 777 engine needs vast amounts of air going thourgh the engine core, in order to produce power, in order to drive the fan!!! It doesn't get it's power from anywhere else! Power comes from the core, but the majority of the thrust comes from the fan. You're confusing the two. This core airflow will unquestionably exceed the air requirement of a small low bypass miltary engine.
There is no "centrifuging" of air in a turbine engine. Unless you consider free turbine engines which generally use a centrifugal compressor, but then these have no bypass! Centrifuging in a bypass jet engine just does not occur!
I can't comment on very fine ash and it's likelihood of blocking cooling passages, but ash also contaminates oil systems and breaches bearing seals, etc, etc. This risk must surely increase with finer ash....