Marine Installation Manual
2021-08
6-1
6 Engine Dynamics
X72DF
6
Engine Dynamics
It is critical that vibration is minimised throughout the design and construction
stage of any engine installations. The assessment and reduction of vibration are
subject to continuous development and research, requiring expert knowledge.
For successful design, vibration behaviour calculations are required over the
whole operating range of the engine and the propulsion system. As such,
WinGD has developed extensive computer software, analytical procedures and
measuring techniques.
Forces and moments
causing vibrations
Within the engine, various forces and moments are generated by the recipro
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cating and rotating masses. Often these cyclical forces and moments are neutral
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ised by counterbalancing within the engine. However, if this is not achieved the
engine will experience the sum of these forces and moment as external responses,
reacting around its own axis and causing vibrations outside of the engine. Vibra
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tions are problematic, especially if a vibration frequency forces a resonance,
causing an amplitude to pass acceptable limits. This section highlights the impor
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tance of dynamic consideration, the causes and relevance.
After considering the external forces and moments types, this section explores
the resulting vibration, along with recommended considerations and counter
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measures relevant to engine type and other associated systems and design fea
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tures.
Types of vibration
The vibration types considered in this section are as follows:
•
External mass forces and moments
•
External lateral forces and moments (Lateral engine vibration or 'rocking')
•
Longitudinal engine vibration
•
Torsional vibration of the shafting
•
Axial vibration of the shafting
•
Whirling vibration of the shafting
•
Hull vibration
Dynamic characteristics
data
The external forces and moments generated by a specific engine defines its dy
-
namic characteristics. These must be considered throughout the design process
of the vessel to avoid adverse impact on the vessel.
In the document
External forces and moments
WinGD provides a complete list
of the external forces and moments for each engine type. The latest version of
this document is provided on the WinGD webpage under the following link:
The external forces and moments for engines not tuned to an R1 rating are avail
-
able on request.
NOTE
WinGD provides additional support services to assist with system dy
-
namics and vibration analysis. For additional information about forms
and links, please see section
.
