Fibre Optic Sensors for Long-Term Monitoring of Oil Film Pressure in Diesel Engine Main Bearing

To predict and analyze accurately the lubrication characteristics and its influencing factors of main bearing for large low-speed two-stroke marine diesel engine, based on EHD lubrication model of dynamically loaded bearing, coupling simulation between EHD and MBD for main bearing of marine diesel engine was carried out. Systemic models were established separately considering the independent crankshaft of diesel engine and the full shafting of propulsion power plant. Main bearing load, peak oil film pressure, oil film pressure distribution, MOFT and orbital path in one working cycle under rated working conditions were investigated, and simulation results were compared based on both models. The results show that, if the impact of full shafting was considered, the lubrication characteristics of No.8 main bearing changed significantly, the lubrication characteristics of other main bearings were similar as the simulation results of the independent crankshaft model.

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The effects of material and structure of main bearing caps on crankshaft lubrication of diesel engine

International Journal of Engine Research ◽

10.1177/1468087419896647 ◽

2020 ◽

pp. 146808741989664

Author(s):

Limin Wu ◽

Yan Fu ◽

Mei Li ◽

Gang Liang ◽

Yanting Zhang ◽

...

Keyword(s):

Diesel Engine ◽

Coupled Model ◽

Engine Block ◽

Main Bearing ◽

Film Pressure ◽

Oil Film ◽

Medium Speed ◽

Lubrication Performance ◽

Bearing Cap ◽

Oil Film Pressure

The elastic deformation of the crankshaft and engine block has important effects on lubrication performance of main bearings of the diesel engine. But the effect of main bearing caps was rarely analyzed. The purpose of this article is to analyze and compare the tribological performances of main bearings of a 20-V medium-speed diesel engine with different materials and structures of main bearing caps. A coupled multi-elastic body and elasto-hydrodynamic model is established for a 20-V medium-speed diesel engine. The deformations of engine block, crankshaft and bearing caps are simulated with finite element modal condensation method. The bearing lubrication analysis is based on the extended Reynolds equation considering the deformation of contact surface and solved by finite difference method. Two materials and four structures of the main bearing cap are analyzed with the coupled model. The distribution of oil film pressure, thickness and bearing thermal loads are obtained and analyzed. The main bearing cap of iron is better than steel on bearing lubrication performance. With the lower edge stiffness of bearing cap, the maximum oil film pressure of bearing can be reduced by 13%. Meanwhile, the bearing thermal load can be reduced by 53%. The results show that when the bearing cap material is iron and with large trough on both sides of bearing cap, the peak value of edge pressure and the average heat load of main bearing can be reduced effectively under the premise of ensuring stiffness.

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ANALYSIS OF THE ACCURACY OF FIBRE-OPTIC STRAIN GAUGES

Acta Polytechnica ◽

10.14311/ap.2013.53.0872 ◽

2013 ◽

Vol 53 (6) ◽

pp. 872-877

Author(s):

Dita Jiroutová ◽

Miroslav Vokáč

Keyword(s):

Fiber Optic ◽

Strain Gauges ◽

Relative Deformation ◽

Fibre Optic ◽

Reinforced Concrete Structure ◽

Structure Monitoring ◽

Fiber Optic Technology ◽

Long Term Monitoring ◽

Term Monitoring

In recent years, the field of structure monitoring has been making increasing use of systems based on fiber-optic technologies. Fiber-optic technology offers many advantages, including higher quality measurements, greater reliability, easier installation and maintenance, insensitivity to the environment (mainly to the electromagnetic field), corrosion resistance, safety in explosive and flammable environments, the possibility of long-term monitoring and lower cost per lifetime. We have used SOFO fibre-optic strain gauges to perform measurements to check the overall relative deformation of a real reinforced concrete structure. Long-term monitoring of the structure revealed that the measurement readings obtained from these fibre-optic strain gauges differed from each other. Greater attention was therefore paid to the calibration of the fibre-optic strain gauges, and to determining their measurement accuracy. The experimental results show that it is necessary to calibrate SOFO strain gauges before they are used, and to determine their calibration constant.

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