Successful Vibration Performance g60me c9

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G60ME-C9 Vibration

PerformanceSuccessful vibration measurements

completed on sea trial





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





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)



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




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



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



Navigation Wings

ISO 6954-1984 upper limit: 9 mm/s

5th order 5G60ME-C9



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


0

5

10

15

20

25

30

35

20 30 40 50 60 70 80 90 100 110


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


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.




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







MAN Diesel & Turbo

Teglholmsgade 41

2450 Copenhagen SV, Denmark

Phone +45 33 85 11 00

Fax +45 33 85 10 30

[email protected]

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

Successful Vibration Performance g60me c9

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