with engine speeds ranging from 3600 rpm to over
15,000 rpm. Some of the engines were stationary
the final noise radiated from the end of the tailpipe
is the PWL of the unmuffled exhaust minus the in-
commercial versions of aircraft engines, while some
were large massive units that have no aircraft
sertion loss, in octave bands, of the reactive muf-
fler (para 3-3).
counterparts. Most of the engines were used to
drive electrical generators either by direct shaft
coupling or through a gear. Eight different engine
2-8. Gas turbine engine noise data.
manufacturers are represented in the data. Engine
a. Data collection. Noise data have been collect-
configurations vary enough that the prediction is
ed and studied for more than 50 gas turbine en-
not as close as for the reciprocating engines. After
gines covering a power range of 180 kW to 34 MW,
deductions were made for engine housings orwrap-
2-8
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