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G60ME-C9 Vibration
PerformanceSuccessful vibration measurements
completed on sea trial
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Contents
Background .................................................................................................5
Cooperation with hull designer .....................................................................5
Vibration focus ............ ...... ...... ...... ...... ...... ...... ...... ....... ...... ...... ...... ...... ...... .. 5
Basic considerations when selecting engine and rating .................................5
Vibration measurements ...... ...... ...... ...... ...... ...... ....... ...... ...... ...... ...... ...... ...... 6
Measurement results ....................................................................................7
Main engine frame ..................................................................................7
Ship structure: navigation deck and wings .............................................. 7
Top bracing system ....... ...... ...... ...... ...... ...... ...... ....... ...... ...... ...... ...... ...... ...... 8
Other vibration measurements ......................................................................8
Vibrations on 6G50ME-C9 ........... ...... ...... ...... ....... ...... ...... ...... ...... ...... .... 8
Summary .....................................................................................................9
Notes .....................................................................................................9
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G60ME-C9 Vibration Performance 5
G60ME-C9 Vibration PerformanceSuccessful vibration measurements completed on sea trial
MAN Diesel & Turbo has succesfully
completed structural vibration meas-
urements on the first Green Dolphin
64,000 dwt bulk carrier propelled by
the new »green« G-type ultra-long
stroke 5G60ME-C9 main engine.
Background
The S60ME-C8 type engine is already
a well-proven propulsion plant for the
64,000 dwt bulk carrier class vessels
and, from a vibrational point of view,
this hull/engine combination has shown
excellent vibration performance. But
the market demand for G-type engines
is increasing, and shipyards and de-
signers are now offering the 5G60ME-
C9 type engine for the 64,000 dwt bulk
carrier class vessels, which previously
had S-type engines installed.
Compared with the S-type engine,
the new G-type engine offers a higher
power at lower engine speeds. As ex-
pected, this changes the main engine’s
external forces and moments transmit-
ted to the ship hull (vibration forces).
Cooperation with hull designer
MAN Diesel & Turbo (MDT) has been
working in close cooperation with both
the hull designer (SDARI) and the en-
gine builder on important installation
aspects influencing the engine and hull
vibration characteristics and perfor-
mance.
MAN Diesel & Turbo has supplied theengine calculation model (5G60ME-C9)
used by the hull designer when per-
forming the global vibration analysis of
this 64,000 dwt bulk carrier newbuild-
ing ordered by an Asian owner (Note 1).
Based on the hull designer’s advanced
calculation model of the ship hull, the
steel structures have been optimised
on both the engine and the hull.
Vibration focus
The G-type delivers higher, but fully
controllable, guide force moments
compared with the S-type engine.
(Note 2).
Special attention has therefore been di-
rected towards the structural vibrations
related to this excitation source. Both
global hull response (vibration) and lo-
cal main engine vibration performance
was carefully measured and analysed,
covering the full operational speed
range of the vessel.
Basic considerations when selecting
engine and rating
Avoiding problematic resonance condi-
tions is a key factor in achieving a suc-
cessful vibration performance.
Resonance
The frequency of a harmonic excita-
tion coincides with the natural fre-
quency of the mass-elastic system.
Depending on the damping of the system, a considerable magnitica-
tion of the response will take place at
resonance. Magnifications of 5 to 50
times will not be unusual.
Fig. 1: Disembarkation from sea trial on 19 January 2014
Fig, 2: Hull calculation model (SDARI) with MDT supplied engine model (5G60ME-C)
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G60ME-C9 Vibration Performance6
When choosing the optimal engine type
and rating, low hull sensitivity towards
the excitation frequency range (firing
frequency in the engine’s operational
speed range) is often the most influ-
ential factor for a successful vibration
performance.
In case of resonance in the operational
speed range, vibrations can be ampli-
fied by a factor of 5-10 as compared
to the non-resonant situation. The in-
crease in guide force moment between
the G and S type can be a factor of
only 1.25 to 1.5, depending on ratings.
Therefore, the actual level of the guide
force moment has less importance to
a successful installation as long as a
“non-resonant” situation is achieved for
the engine hull combination.
Vibration measurements
The actual vibration measurements
were taken during sea trials in the East
China Sea near Shanghai in January
2014.
Propulsion of the bulk carrier:
Main engine: 5G60ME-C9
MCR: 8,500 kW x 77 rpm.
Main particulars of the bulk carrier:
Shipyard: New Hantong S/Y
Deadweight at scantling: 64,000 dwt
Length between pp: 194.5 m
Breadth lmd: 32.26 m
Draught design: 11.3 m
Propeller: 5 blades
Fig. 3: Engine frame transverse vibration level (100% G-type (L4) = 77 rpm, 100% S-type (L1) = 105 rpm)
0
5
10
15
20
25
30
35
30 40 50 60 70 80 90 100 110
Per cent [%] of MCR speed
Main Engine Frame
MDT recommended vibration limit: 25 mm/s (Zone 1)
V i b r a t i o n [ m m / s ] , 0 - p e a k
G-type rating L4: MCR 77 rpm S-type average rating L1: MCR 105 rpm
5G60ME-C95th order
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G60ME-C9 Vibration Performance 7
Measurement results
Main engine frame
The transverse vibration level of the
engine frame (cylinder frame top) was
dominated by vibrations at frequencies
5 times the engine speed (5th order).
The excitat ion sources are the propeller
(5 blades) and the main engine guide
force moment (also 5th order, firing fre-
quency).
The vibration measurements illustrated
in Fig. 3 show low and fully accepta-
ble vibration levels for the main engine
structure. The vibration level was well
within MAN Diesel & Turbo’s permissi-
ble limits for the engine frame (Note 3).
Compared with an average vibration
level for an S-type engine (based on
8 reference vessels, Note 4), it is clearthat the hull and engine vibration per-
formance has been improved for the G-
type engine, see Fig. 3.
Furthermore, the local main engine
structures and components, such as
turbochargers, seatings, platforms, ex-
haust gas receivers, etc., showed low
and fully acceptable vibration levels.
Ship structure: navigation deck and
wings
The vibration level of the navigation
deck (5th order) was normal and fully
acceptable (within ISO 6954 limits), see
Figs. 4 and 5.
The measured response was dominat-
ed by 5th order vibrations. Compared
with measurements taken on the main
engine frame, a higher propeller in-duced vibration was recorded.
Fig. 4: Navigation deck vibration level (100% G-type (L4) = 77 rpm)
Fig. 5: Navigation deck wings vibration level (100% G-type (L4) = 77 rpm)
0
3
6
9
12
30 40 50 60 70 80 90 100
navigation deck - transverse navigation deck - vertical navigation deck - longitudial
Navigation Deck
V i b r a t i o n [ m m / s ] , 0 - p e a k
Per cent [%] of MCR speed
ISO 6954-1984 upper limit: 9 mm/s
5th order 5G60ME-C9
0
3
6
9
12
30 40 50 60 70 80 90 100
navigation deck wing - transverse navigation deck wing - vertical navigation deck wing - longitudial
Per cent [%] of MCR speed
V i b r a t i o n [ m m / s ] , 0 - p e a k
Navigation Wings
ISO 6954-1984 upper limit: 9 mm/s
5th order 5G60ME-C9
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G60ME-C9 Vibration Performance8
Top bracing system
The top bracings of the main engine
connect the engine frame top level with
the hull side structure.
The main purpose of this system is to
shift the natural frequency (H-mode) out
of the operational speed range to avoid
a resonance condition (Ref. 1).
The 5G60ME-C engine was installed
with a double-sided top bracing system.
This system comprises top bracings on
both sides of the engine structure (star-
board side and portside).
During sea trial, measurements were
also taken with only single-sided top
bracings connected (on starboard side).
These measurements showed similar
positive results on both the main engineframe (Fig. 6) and the navigation deck.
Other G-type vibration measurements
Vibrations on 6G50ME-B9
Recent measurements taken by MAN
Diesel & Turbo research engineers on
the first 6G50ME-B9 engine during
sea trial in February 2014 indicate very
promising results for the G-type engine
series.
Sea trial measurements performed on:
6G50ME-B9.3
7,700 kW x 93.4 rpm.
Oil/chemical tanker (49,780 dwt)
Vessel size 183 x 32m
The vibration values measured are
equally low as measured for the
5G60ME-C9 engine, see Fig. 7.
0
5
10
15
20
25
30
35
30 40 50 60 70 80
Engine speed [rpm]
Main Engine Frame
V i b r a t i o n [ m m / s ] ,
0 - p e a k
top bracings (starboard side only) top bracings (starboard + portside)
5G60ME-C95th order
MDT recommended vibration limit: 25 mm/s (Zone 1)
0
5
10
15
20
25
30
35
20 30 40 50 60 70 80 90 100 110
Per cent [%] of MCR speed
5G60ME-C9.2 / 6G50ME-B9.3 Main Engine Frame
V i b r a t i o n [ m m / s ] ,
0 - p e a k
MDT recommended vibration limit: 25 mm/s (Zone 1)
5G60ME-C9.2 - sea trial Januray 2014, MCR: 8,500 kW x 77 rpm 6G50ME-B9.3 - sea trial February 2014, MCR: 7,700 kW x 93.4 rpm
Fig. 6: Top bracing measurement results for 5G60ME-C9 (SDARI HT64-120)
Fig. 7: Sea trial vibration measurement results for G50/60 engine types
Average tanker/bulker hulls installed
with 50/60 bore engine sizes normally
show increased sensitivity for guide
force moment excitations (H-type)
in the higher speed ranges, which is
where S-types often operate.
This makes the G-type engine a very
suitable choice for these hull types,
as it is designed to operate in a lower
speed range.
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G60ME-C9 Vibration Performance 9
Summary
Vibration measurements on the new G-
type engine show low and fully accept-
able global vibration conditions on both
the main engine frame and the vessel
superstructure.
When comparing this G-type instal-
lation (HT 64-120) with most other
S-type installations, it is clear that
the vibration response is improved.
With the right design of the influen-
tial hull structures, the hull designer
has succeeded in developing a
smoothly performing hull/engine
combination.
Local main engine structures and
components such as turbocharg-
ers, platforms, exhaust gas receiv-
ers, etc., benefit from the low main
engine frame vibration. Local mainengine structures show low and fully
acceptable vibration levels.
Vibration forces are controlled with
well-proven standard countermeas-
ures (top bracings).
Improved fuel oil consumption is
achieved with 5G60ME-C9.
SDARI ship design of Green Dol-
phin 64,000 dwt bulk carrier with
5G60ME-C9 is available.
Notes
Note 1
A full range of engine calculation mod-
els (finite element model) are available
(free of charge) from the MAN Diesel &
Turbo extranet website called Nexus.
The engine calculation models are add-
ed to the shipyard’s hull model, thereby
obtaining an accurate calculation mod-
el of the combined system.
Note 2
The so-called guide force moments are
caused by the gas force on the piston
and by the inertia forces. The H-type
type guide force, which is dominant on
the 5-cylinder engine, tends to rock the
engine top in transverse direction.
Note 3
MAN Diesel & Turbo vibration limits(single order, 0-peak):
Zone 1 [0-25 mm/s]: recommended.
Zone 2 [25-50 mm/s]: acceptable
for main engine. Under adverse
conditions, annoying/harmfull vibra-
tions may occur in the connected
structure/vessel.
Zone 3 [> 50 mm/s]: not acceptable
for main engine.
Note 4
S-type average vibration level.
MDT vibration measurements used in
average (5-cylinder S60 bore types):
5S60MC-C (11,300 kW x 105 rpm):
crude oil tanker (73,626 t),
size: 228 x 32 m
5S60MC-C (11,300 kW x 105 rpm):oil products tanker (46,098 t),
size: 183 x 32 m
5S60MC-C (11,300 kW x 105 rpm):
oil products tanker (69,554 t),
size: 228 x 32 m
5S60MC-C (11,300 kW x 105 rpm):
bulk carrier (75,750 t),
size: 225 x 32 m
5S60MC-C (11,300 kW x 105 rpm):
oil products tanker (46,011 t),
size: 183 x 32 m
5L60MC-C (6,650 kW x 111 rpm):
fruit juice tanker (15,108 t),
size: 146 x 22 m
5S60MC-C (8,990 kW x 92 rpm):
bulk carrier (74,477 t),
size: 225 x 32 m
5S60MC-C (11,900 kW x 105 rpm):general cargo ship (49,924 t),
size: 208 x 32 m
References
Ref. [1] - Vibration Characteristics of
Two-stroke Low Speed Diesel Engines,
MAN Diesel & Turbo paper, Id. no.:
p9301-268
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MAN Diesel & Turbo
Teglholmsgade 41
2450 Copenhagen SV, Denmark
Phone +45 33 85 11 00
Fax +45 33 85 10 30
www.mandieselturbo.com
MAN Diesel & Turbo – a member of the MAN Group
All data provided in this document is non-binding. This data serves informational
purposes only and is especially not guaranteed in any way. Depending on the
subsequent specific individual projects, the relevant data may be subject to
changes and will be assessed and determined individually for each project. This
will depend on the particular characteristics of each individual project, especially
specific site and operational conditions. Copyright © MAN Diesel & Turbo.
5510-0166-00ppr Feb 2014 Printed in Denmark