The Study On The Piston Performance Of Low Speed Marine Diesel Engine

Diesel engine have been invented for more than 100 years and it is well known for its high thermal efficiency, large power range and good mobility. With society progress and new requirements, higher detonation pressure, power and speed are the direction of future internal combustion engine. As power increases, thermal load and mechanical load of the engine will increase. Piston is the main driving and bearing part of the engine, so the reliability and service life of engine mostly depend on piston performance. When engine is in working condition, the piston bears thermal load and mechanical load at the same time, making stress analysis complicated. Therefore, it is necessary for engine development to conduct simulation calculation, including assessing strength property, stiffness performance and reliability.This article focuses on marine low-speed diesel engine which is in the stage of research and development. Use finite element analysis software to conduct simulation and check strength, stiffness, stability and fatigue performance of piston parts. Following are the study tasks.(1) Based on thermal analysis theory, build a piston fluid-structure interaction model. Use fluid dynamics software and finite element analysis software to conduct simulation calculation in order to acquire boundary conditions of coupling surface of fluid and solid region. Then determine the piston temperature field distribution on the basis of above boundary conditions.(2) Based on piston stress filed analysis theory, use finite element analysis software to build finite element model. Consider piston temperature field distribution results as temperature boundary to simulate the thermal load. Add mechanical load by calculated and known data to the piston, making comparison and analysis. So we can predict strength, stiffness and danger area of piston part. Stability analysis of piston rod will help to research buckling performance. At last, based on VDI2230 bolt strength calculation standard, conduct validation of bolt dynamic fatigue performance. The results show that strength, stiffness and stability of piston part comply with designation requirements.(3) Based on fatigue analysis theory, use fatigue analysis software to analyze main parts of piston and predict fatigue danger area and fatigue safety factor. The result shows the safety factor of the main piston parts comply with designation standards.Above study will prove the rationality of piston part designation and provide foundation for future piston designation and manufacturing process.