noise, the turbocharged air inlet noise (if applica-
25 and 26) minus the insertion loss of the muffler
ble, and with or without sound absorption material
used, in octave bands.
in the inlet ducting), and the engine exhaust noise,
with and without an exhaust muffler.
2-9. Data forms.
b. DD Form 2305. DD Form 2305 (Estimated
Several data forms are developed and illustrated in
Sound Power Level of Gas Turbine Engine Noise)
the N&V manual. These forms aid in the collection,
summarizes the data and procedures for estimating
organization, and documentation of several calcula-
the unquieted and quieted engine casing noise, air
tion steps that are required in a complex analysis
inlet noise., and engine exhaust noise (app A). Ad-
of a noise problem. Instructions for the use of those
ditional engine data and discussion are given in
data forms (DD Forms 2294 through 2303) are giv-
paragraph 2-8 above, and the insertion losses of a
en in the N&V manual, and blank copies of those
few sample muffler and duct configurations are giv-
data forms are included in appendix E of that man-
en in paragraphs 34 and 35.
ual. Many of the forms are used in the chapter 4
c. Sample calculations.
Sample calculations
examples. In addition, two new DD forms are pre-
using these two new data forms (DD Form 2304
scribed in this manual.
and DD Form 2305) appear in chapter 4.
a. DD Form 2304. DD Form 2304 (Estimated
Sound Power Level of Diesel or Gas Reciprocating
2-10. Other noise sources.
Engine Noise) summarizes the data procedures re-
Gears, generators, fans, motors, pumps, cooling
quired to estimate the PWL of a reciprocating en-
towers and transformers are other pieces of equip-
gine (app A). Data for the various steps are ob-
ment often used in engine-driven power plants. Re-
tained from paragraph 27 above or from an engine
fer to chapter 7 of the N&V manual for noise data
manufacturer, when such data are available. Parts
on these sources.
A, B, and C provide the PWLs of the engine casing
2-13
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