Re: Surge on GE90

From:         whurwitz@world.nad.northrop.com (Wayne M. Hurwitz)
Organization: Northrop Grumman Information Services Center, Hawthorne, CA
Date:         07 Jul 95 14:26:19 
References:   1 2
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In article <airliners.1995.841@ohare.Chicago.COM> simonlc@ozemail.com.au (Simon Craig) writes:
>> I have a question... When an engine such as the GE90
>> is starting, what controls which direction the combusted
>> material is expelled from the combustion chamber?  I guess
>> only?
>
>The engine is pun up by the starter through the gearbox, which is directly
>driving the high speed turbine/compressor shaft.  This generates airflow

Is this correct for the GE90?  My experience is that engines are started
with air turbine starters, which actually inject air into the turbine
to rotate the shaft.  The compressed air source comes from either an
APU or cross bleed from an engine that is already running.  But then
I deal mostly with military applications, which may be different.  On
the other hand, it seems like it would take an awful lot of electrical
power to spin up a GE90, which would be prohibitive when sizing a
starter/generator.


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Wayne M. Hurwitz                 | Phone:  (310) 948-6567
Northrop Grumman Corporation     | Fax:    (310) 942-6464
B-2 Business & Advanced Systems  | Email: whurwitz@world.nad.northrop.com