King Air C90GTi, Руководство по подготовке пилотов

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FREE-TURBINE REVERSE-
FLOW PRINCIPLE
The Pratt and Whitney PT6 f amily of en-
g i n e s c o n s i s t s b a s i c a l ly o f f r e e - t u r b i n e ,
r eve r s e - f l ow e n g i n e s d r iv i n g a p r o p e l l e r
t h r o u g h p l a n e t a r y g e a r i n g ( Fi g u r e s 7 - 3 ,
7-4, 7-5, and 7-6). The ter m “free-turbine”
refers to the design of the turbine sections
of the engine. There are two turbine sec-
tions: one, called the compressor turbine,
wh i c h d r ive s t h e e n g i n e c o m p r e s s o r a n d
accessories; and the other, consisting of a
s i n g l e p owe r t u r b i n e , w h i c h d r i v e s t h e
p owe r s e c t i o n a n d p r o p e l l e r. T h e p owe r
turbine section has no physical connection
to the compressor turbine at all. These tur-
bines are mounted on separate shafts and
are driven in opposite directions by the gas
flow across them. The ter m “reverse flow”
refers to airflow through the engine. Inlet
air enters the compressor at the aft end of
t h e e n g i n e , m ov e s f o r w a r d t h r o u g h t h e
comb ustion section and the turbines, and
is exhausted at the front of the engine.
KING AIR C90GTi/C90GTx PILOT TRAINING MANUAL
7-4
FOR TRAINING PURPOSES ONLY
7
POWERPLANT
Figure 7-3. Free Turbine