CIMAC Congress - Schiff & Hafen

CIMAC CONGRESS | BERGEN 2010
the high reliability and low cylinder oil feeding rate are the very
important subject for engine builders. The study for revealing the
factors which affects to the lubricating conditions of piston rings and
cylinder liners are effective to develop the new highly reliable and
low operation cost engine. This paper describes the long term
continuous measurement results of the oil film thickness, the contact
electric resistance between the piston rings and the cylinder liner, the
iron content in cylinder drain oil, and the pressure between piston
rings. The oil film thickness and the contact electric resistance are
measured with newly developed sensors, and they are measured
with same sensor by switching the electric circuit. The low speed twostroke
diesel engine for the 280,000 t VLCC was selected for this
measurement. The special 28 sensors which are made inhouse are
installed into the drilled holes at the cylinder wall, and the
circumference direction and stroke direction oil film thickness
distribution are measured. Automatic continuous measurement
enabled to collect huge data under various engine operating
condition during two years. The factors which affect to the long term
oil film thickness variation trend after maiden voyage, the factors
which affect to the short term variation in oil film thickness, contact
condition between piston rings and cylinder liner, and the iron
content in cylinder drain oil are clarified by the data analysis.
According to the factors, the actual method to improve the sliding
condition of piston rings and cylinder liners are studied. As a result,
the reason why the wearing speed of the coating of the 2 nd and 4 th
piston ring is different, the influence that differential pressure at the
piston rings and its variation exerts on the sliding condition, and
other useful mechanism have been clarified.
Intelligent monitoring of journal bearings
A. Valkonen, J. Juhanko, P. Kuosmanen, Helsinki
University of Technology, Finland,
J. Martikainen, Mikkeli University of Applied
Science, Finland
Journal bearing are used in demanding applications in mechanical
engineering like in internal combustion engines and heavy rolls in
paper and steel industry. The main guidelines in design of journal
bearing are to avoid wearing of sliding surfaces and to keep power
loss caused by friction reasonable. Therefore, the sliding bearings
are typically designed to operate at hydrodynamic lubrication
conditions. During the hydrodynamic lubrication, the pressure
formed on the lubrication film by sliding separates the bearing and
the shaft and, thereby, keeps the wear and friction at low levels. In
research and industry there is a great demand to find a sensor which
measures the real pressure of the lubrication film and which could
be used under demanding conditions, for example in bearings of
an operating internal combustion engine. This measuring
information could be used in online monitoring. In addition,
measurements of the thickness and pressure of the lubrication film
could be used to verify the results of bearing simulation. The main
aims presented in this paper were to introduce methods for
measuring of the thickness and pressure of the lubrication film, and
to demonstrate the feasibility of optical pressure sensors for
measuring the oil film pressure. The vision in developing more
sophisticated machine elements like intelligent journal bearings is
to be able to indicate the key parameters continuously. This is
required also in intelligent condition monitoring. The results
proved that thin film pressure sensors could measure quite
accurately the real film pressure. Measurement is easy to carry out in
test bench and possible also in demanding environment like
combustion engines. Anyway, the method is still new and
manufacturing of sensors requires special technology, which is
expensive in low quantities. Sensors are also damaged if thin
insulator film is worn out. Next steps are to prepare a full scale
sliding bearing and make the tests in dynamic bearing test rig.
Optical sensor operated well in test conditions with high bearing
loads, speeds and operating temperature. The relative errors in the
measurement of the oil film pressure was about ±5%. Significant
differences between the measured and simulated oil film pressure
distributions were found. Typically, the measured area of high
pressure in the lubricating oil film was wider than the simulated
one. The results can be used in the development and validation of
mathematical methods in hydrodynamic journal bearing research.
The Universal concept: the lubrication
solution to 2020 and beyond
D. Lancon, V. Doyen, Total Raffinage Marketing,
France
Current IMO regulations have led ships to burn bunker fuel of
varying sulphur contents. Future emissions regulations are likely to
mandate the use of more extreme fuels with strongly varying
composition and combustion quality. The drive to design engines
with more power per cylinder, the advent of the electronically
controlled engine and the push to minimize cylinder lubricant feed
rates, all add pressure that is further increasing the performance
constraint on the lubricant. An in-depth understanding of the
neutralization mechanism and the interactions between two-stroke
slow speed engine operation and the lubricant behaviour (1,2,3) led
Total Lubmarine two years ago to introduce Talusia Universal. The
formulation of this lubricant avoids the necessity for the ship
operator to switch cylinder lubricant when changing from high to
low sulphur fuel (4). The knowledge built with the Universal
concept is now being extended to fit the upcoming emission
regulations planned for the period 2015 to 2020 and beyond. Base
Number levels will decrease, yet antiwear, thermal stability, resistance
to deposit formation and detergency need to be maintained to
ensure good engine operation and long term reliability. This paper
details several novel technical aspects related to our understanding
of the degradation mechanism from new cylinder lubricant to drain
oil. Deposits found in drain oil, are representative also of these
found in the piston ring packs, and are of great interest in their
understanding. They provide information on the transformation of
cylinder lubricant during its passage down the liner wall and its
degradation into drain oil. An in-depth identification of the chemical
nature and size distribution of particles, down to a nanoscale, is
applied. Thanks to these result, a laboratory procedure has been
developed to mimic the formation of these deposits. One further
step is to determine the hardness of these deposits, which can differ
from one formulation to another one. The paper then reviews how
the lubricant formulation can interact with the degradation
mechanism to maintain a safety margin from the top to the bottom
of the cylinder liner. It finally proposes the Universal concept as a
sustainable lubricating solution from now to 2020 and beyond.
This concept allows the lowering of BN whilst maintaining efficient
neutralization and avoiding excessive wear.
1 “From fresh cylinder lubricant to drain oil – an evaluation of its
performance profile” by D. Lancon, J.- M. Bourmaud and E. Matray,
ISME Conference Tokyo 2005
2 “Advanced applied research unravelling the fundamentals of
2-stroke engine cylinder lubrication – an innovative on-line
measurement method based on the use of radioactive tracers –” by
V. Doyen, R. Drijfholt and T. Delvigne, CIMAC Conference Vienna
2007
3 “Engine operating and mapping – the next step in drain oil
analysis” by D. Lancon, accepted for publication at ISME Conference
Busan 2009
4 “Talusia Universal: the perfect fit” by J.-P. Roman, Marine
Propulsion Conference London 2009
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Ship & Offshore | 2010 | No. 3