Thermo-elasto-hydrodynamic Mixed Lubrication of Main Bearings of Marine Diesel Engines, Based on Coupling between Flexible Engine Block and Crankshaft

Flexible whole engine block and flexible crankshaft are built by CMS method. Under coupling between them, based on the generalized Reynolds considering mass-conserving boundary condition and Greenwood/Tripp asperity contact theory, Thermo-elastic-hydrodynamic mixed lubrication model of main bearings of marine diesel engines is developed and validated indirectly. Simultaneously, calculation shows that mixed lubrication is normalcy, while full hydrodynamic film lubrication is transient. Cavitation erosion becomes a very real possibility only when cavitations, centripetal or centrifugal movement of crankshaft and suddent change of film pressure gradient occur simultaneously. As oil leakage dissipated power is more than 80 percent of the whole dissipated power, outlet film temperature can be a key parameter for monitoring journal bearing lubrication. 8 pieces of bearings meet the requirement of lubrication basically, but work condition of two of the bearings is worse and they need be optimized furthermore. copyright 2014 Journal of Mechanical Engineering.