shaft lateral analysis overview
DESCRIPTION
Presentation delivered by Mohamed Zeid from Berg Propulsion on Nauticus Machinery Course, Rio de Janeiro, September 2012TRANSCRIPT
Shaft Lateral Analysis overview
Name: Mohamed Zeid
Live in: Sweden
Age: 32
Role: Senior Rotordynamics Engineer.
Education:
B S I N l A hi & M i i i f f l f i i S C l U i i 2003B.Sc. In Naval Architecture & Marine engineering from faculty of engineering, Suez Canal University 2003.
AMRINA , Associate Member at Royal Institution of Naval Architects.
Practical Experience:
[Jun to Sep, 2000], Suez Odense Marine Service (Training).
[Jun to Sep,2001:2003], Consulting Engineering Bureau (Training).
[Nov2003‐May2004], Ocean Classic International, (Structural analysis ).
[May 2004‐Jul 2005], TIMSAH Shipyard , (Hydrodynamics , Structural analysis,...)
[Jan 2006‐ ......], BERG PROPULSION, (Blade design, Shafting design and analysis / calculations,.....)
2DNV Software User Conference
Rio ,Sep 2012
Propeller shaft alignment Background,Analysis and ControlAnalysis and Control.
Alignment backgroundAlignment background.
• Straight installation for all the bearings and the gearbox for installation
purposes onlypurposes only.
3Shaft analysis overview Sep2012‐MZ‐Rio
Alignment background.
• Straight installation for all the bearings and
position the gearbox flange to face the flange
of the propeller shaftof the propeller shaft.
GB
SHAFT
Shaft analysis overview Sep2012‐MZ‐Rio
4
Alignment background.
Alignment calculations?g
Shaft analysis overview Sep2012‐MZ‐Rio 5
Alignment background.
Shaft Analysis in Lateral
Shaft analysis overview Sep2012‐MZ‐Rio 6
Alignment background.
• Complete shaft analysis and positioning the shaft line bearings including the
gearbox / main engine to fulfill the allowable loading criteria for all shaft
componentcomponent.
Shaft analysis overview Sep2012‐MZ‐Rio 7
Alignment background.
Shaft analysis overview Sep2012‐MZ‐Rio 8
Determine optimum domain.
Straight ahead analysisOperating Condition Vessel loading condition
Shaft analysis overview Sep2012‐MZ‐Rio 9
Propeller shaft Analysis and Control.
Modeling the shaft system
Shaft line deflection and bending stresses.
AnalysisReposition and adjusting
the bearingNOT Ok
gOk
Bearing loads
Other shaft componentOk
NOT Ok
NOT Ok p(Seals, breaks, couplings,…..)
Ok
Describe how the bearingpositioned (GAP/SAG).
NOT Ok
positioned (GAP/SAG).
Verifying the alignment. (Jack load)
R i
Shaft analysis overview Sep2012‐MZ‐Rio 10
Reporting.
Modeling the shaft system.
• The tool used for build the model is NAUTICUS MACHINERY, SHAFTThe tool used for build the model is NAUTICUS MACHINERY, SHAFT
ALIGNMENT which developed by DNV.
• The shaft system modeled by the geometric of the shaft components.
• The model also is including the propeller load, gear tooth
forces, stuffiness and thermal expansion effect.
• All the above is modeled for different operating Vertical : Horizontal :
p g
conditions as:
‐Propeller static & Gearbox cold.
‐Propeller static & Gearbox warm.
‐Propeller running at full pitch & Gearbox cold.
‐Propeller running at full pitch & Gearbox warm
Ft
Fa
Fr Fbt
Shaft analysis overview Sep2012‐MZ‐Rio 11
Propeller running at full pitch & Gearbox warm.
‐Propeller running at 0‐pitch & Gearbox warm.
r
Shaft line deflection and bending stresses.
• Checking the shaft deflection through all conditions and look if there is any
excessive deflection specially near by the bearing location.
Shaft analysis overview Sep2012‐MZ‐Rio 12
Shaft line deflection and bending stresses.
• Checking the bending stresses through all conditions and look into the bending
stresses specially in the way of the propeller and in between the bearings.
M
σz-max
Shaft analysis overview Sep2012‐MZ‐Rio 13
High slope of the shaft inside the aft sterntube bearingtube bearing.
• Checking the shaft deflection inside the aft stern tube bearing and ensureChecking the shaft deflection inside the aft stern tube bearing and ensure
that there is enough lubricating film between the shaft and the bearing.
White metalLubricant White metalLubricant
Bearing pressure
Shaft analysis overview Sep2012‐MZ‐Rio 14
High slope of the shaft inside the aft sterntube bearingtube bearing.
• What’s happening in this case?!What s happening in this case?!
The oil film thickness is decreased by increasing the relative slope
0 3ness [m
m]
0.4
0
0.2
0.3
l film
thickn
Slope of shaft,[mm/m]
0.20.1
0 3
0Minim
um oil
0,1[mm/m]0.3
Shaft analysis overview Sep2012‐MZ‐Rio 15
21.50 1M
Bearing length / shaft diameter
High slope of the shaft inside the aft sterntube bearingtube bearing.
• Solution !
Bearing pressure
Shaft analysis overview Sep2012‐MZ‐Rio 16
High slope of the shaft inside the aft sterntube bearingtube bearing.
• Examples !p
Bearing material yielded under the high bearing pressure due to high slope and the bearing still working
Bearing damaged due to high slope of the shaft inside the bearing.
Shaft analysis overview Sep2012‐MZ‐Rio 17
slope and the bearing still working.
Bearing loads criteria.
• Slide surface bearing minimum load !g
The bearing have to be loaded with a minimum load which avoiding the bearing wiping / burning.
Shaft analysis overview Sep2012‐MZ‐Rio 18
Bearing loads criteria.
• Slide surface bearing max load !g
The bearing have to be loaded below the maximum load
which avoid to over load the bearing.
‐Projected pressure in aftmost bearing should not exceed 8 bar (Oil lub.).
‐Projected pressure in other journal bearings should not exceed 12 bar in the lower speed range and 18 bar in the upper speed range (Oil lub.).
• Ensure the direction of the resultant force is far
from the lubricant feeding grooves !
Shaft analysis overview Sep2012‐MZ‐Rio 19
from the lubricant feeding grooves !
Bearing loads criteria.
• Roller bearing minimum load !g
The bearing have to be loaded with a
minimum load which avoiding the bearing
slipping and hammering effect.
Shaft analysis overview Sep2012‐MZ‐Rio 20
Bearing loads criteria.
• Roller bearing maximum load !g
The bearing have not to be loaded more than the maximum load which
allowed by the bearing manufacture to achieve the required life time.
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Other shaft component (Seals, breaks, couplings )couplings…)
• Seals‐ In case of one stern tube bearing installations, the deflection of the shaft at the
location of fwd seal is of interest.
‐ In case of the aft stern tube bearing was slope bored by taking off material from the g p y g
aft end of the bearing, The aft seal adjustment tolerance have to be checked.
• Breaks‐ The brake type and compatibility with the shafting system should be checked .yp p y g y
At Rest Start‐up During Operation
• Couplings and other components‐ The couplings and all other integrated devices compatibility with the shafting system
Shaft analysis overview Sep2012‐MZ‐Rio 22
should be checked and related criteria from the device manufacture have to be fulfilled.
Describe how the bearing positioned.GAP/SAGGAP/SAG
• GAP‐SAG methodThe GAP/SAG method have been found that the most reliable way toThe GAP/SAG method have been found that the most reliable way to
describe how the bearings positioned related to each other.
SAGy1
SAG
A BAB
A BSAGA B
y3GAP
Shaft analysis overview Sep2012‐MZ‐Rio 23
Describe how the bearing positioned.GAP/SAGGAP/SAG
• GAP‐SAG methodThe GAP/SAG method have been found that the most reliable way toThe GAP/SAG method have been found that the most reliable way to
describe how the bearings positioned related to each other.
SAG xSAG
A B1A
B
A BSAGA B
x3
GAP
24Shaft analysis overview Sep2012‐MZ‐Rio
GAP/SAG
SAG installation!t
Seen from aft
sag
B
y1 Bx1
x4x2 s.bp.s.
top
AB sag
Ax3
42p
B
3
bottom
Vertical sag (A below B) = (x3-x1)/2Rotating forward shaft (B) with dial gauge
sagA
B
y3
Horizontal sag (A to s.b. from B) = (x4-x2)/2
Vertical sag (B below A) = (x3-x1)/2Rotating aft shaft (A) with dial gauge
Shaft analysis overview Sep2012‐MZ‐Rio 25
Horizontal sag (B to s.b. from A) = (x4-x2)/2
GAP/SAG
GAP installation!
AB
y1
topSeen from aft:
B
y3
y4y2s.b p.s.
bottom
gap Vertical gap (at bottom) = y3-y1
Rotating forward shaft (B) with dial gauge
bottom
Horizontal gap (at s.b. side) = y4-y2
Vertical gap (B below A) = y3-y1
Rotating aft shaft (A) with dial gauge
Shaft analysis overview Sep2012‐MZ‐Rio 26
Horizontal gap (B to s.b. from A) = y4-y2
GAP/SAG
• Why the GAP/SAG is a reliable method?The reason of GAP/SAG reliability is that this method is a describe how the shaft lineThe reason of GAP/SAG reliability is that this method is a describe how the shaft line
parts relate to each other and then compensating the bearing position to keep the shaft
line as it wanted to come over the change on the hull deflection which changed after
launching .g
Shaft analysis overview Sep2012‐MZ‐Rio 27
GAP/SAG
• GAP/SAG ToleranceAny alignment calculation have to provide a minimum tolerance of +/‐ 0.05 mm for bothAny alignment calculation have to provide a minimum tolerance of +/ 0.05 mm for both
GAP and SAG figures.
Why?!
‐ Manufacturing quality.
‐ Tool accuracy in use.
‐ Practical experience.
Important note: The GAP and SAG
tolerance they are influencing each other!
Shaft analysis overview Sep2012‐MZ‐Rio 28
GAP/SAG
• GAP/SAG measuring tools
Dial gauge. Laser equipment.
Shaft analysis overview Sep2012‐MZ‐Rio 29
Verify that the alignment have been donecorrectlycorrectly.
After aligning the shaft with the GAP‐SAG method, the alignment
have to be checked that it is done correctly.
Jack load method.
X [mm]
F1 F2 F3 F4
F [kN]
F
Fj
CorrFF j ⋅=3
F
Shaft analysis overview Sep2012‐MZ‐Rio 30
Fj F3
Jack load test.
actual jacking curve 1actual jacking curveincluding hysteresisfrom friction
1
X [mm]
theoretical jacking curve
23jacking curve 3
F [kN]1 23
Shaft analysis overview Sep2012‐MZ‐Rio 31
Fj
Alignment verfication
Load cell
Shaft analysis overview Sep2012‐MZ‐Rio 32
Alignment verfication
Jack load notes!
The jack load results can very a lot due to:
‐ Shaft manufacturing quality.60
Jacking Bearing
‐ Tools accuracy.
20
30
40
50
Jack
load
[kN
]
y
‐ Practical experience.
0
10
0 90 180 270
Degrees
Shaft analysis overview Sep2012‐MZ‐Rio 33
Jack load tips!
Checking that the dial gauge not influenced by the jack stiffness and foundation:
x x
F F
Shaft analysis overview Sep2012‐MZ‐Rio 34
Jack load tips!
400
Int. bearingFwd stern bearing
Jack correction factor: Cj=1.0154
K kl i f C 0 9727
Shaft analysis overview Sep2012‐MZ‐Rio 35
Knuckle point factor: Cj=0.9727
Jack load tips!
1300
Int. bearingFwd stern bearing
Jack correction factor: Cj=1.0370
Knuckle point factor: Cj=0.8917
Shaft analysis overview Sep2012‐MZ‐Rio 36
j
Jack load tips!
Bearing with no load, or jacking to short.Check slope !
Too much friction loss Stick-slip, oil suction,pump pulses
Jacking ntil contact
0.001
Initial contact Several bearings
Shaft analysis overview Sep2012‐MZ‐Rio 37
Jacking until contact in top of bearing
Initial contact in top of bearing
Several bearingsunloaded
Alignment verfication
• Strain gauge method
- More complicated measurements- Require bending moment in the shaft- Costly
Commutatortransformer
Pick-Up
- Often much time needed to analyse- Few companies are able to carry out the analysis
+ Accurate+ Analytical solution possible for some shafting systems+ Hot running condition can be verified+ Data stored online
Antenna, Wire around shaft
Strain gauge
Shaft analysis overview Sep2012‐MZ‐Rio 38
PC etc.
Reporting
• The classification societies have a standard requirements in case of the alignment report is
required.
Alignment report structure:
‐ Complete shaft analysis.p y
‐ Alignment method (GAP‐SAG).
‐ Alignment verification (Jack load).
Ali t d‐ Alignment procedures.
Shaft analysis overview Sep2012‐MZ‐Rio 39
Questions ?
Questions and discussion !
Mohamed ZeidN l A hit t R t d i S i li t
BERG PROPULSION PRODUCTION AB
Naval Architect - Rotordynamics Specialist
Direct: +46 31 30 10 736Mobile: +46 761 175 022E-mail: [email protected]
Box 1005 Box 1005 475 22 ÖckeröSweden Office: +46 31 976 500
www.bergpropulsion.com
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