WÄRTSILÄ WARTSILA 20, Product Manual

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16. Vibration and Noise
Wärtsilä 20 generating sets comply with vibration levels according to ISO 8528-9. Main engines
comply with vibration levels according to ISO 10816-6 Class 5.
16.1 External forces and couples
Some cylinder configurations produce external forces and couples. These are listed in the
tables below.
The ship designer should avoid natural frequencies of decks, bulkheads and superstructures
close to the excitation frequencies. The double bottom should be stiff enough to avoid
resonances especially with the rolling frequencies.
Fig 16-1 Coordinate system
Table 16-1 External forces
Fz [kN] Frequency [Hz] Speed [rpm] Engine
-
1
30
60 900 W 4L20
-
1
33.3
67
1000
2 60 900 W 8L20
3 66.7 1000
F
Z
= 0, F
Y
= 0 and F
X
= 0 for 6 and 9 cylinder engines
Wärtsilä 20 Product Guide - a13 - 6 September 2016 16-1
16. Vibration and Noise Wärtsilä 20 Product Guide