Abstract
Internal combustion engines take up the major position in the power facility market and still encounter some challenges; one key issue is liner cavitation erosion. The impact vibration between piston and cylinder generates pressure fluctuation on the wet liner surface and leads to the occurrence of cavitation in the case that coolant pressure falls below its vapor pressure. Piston slap methodology has been improved by considering the dynamic characteristics of the piston. Water coolant passage acoustic features were investigated and the Helmholtz effect between cylinders was confirmed. In order to address the cavitation erosion potential of the engine cylinder, acoustic pressure in the cooling water passage was investigated by boundary element method analysis with the acceleration of the cylinder liner which was obtained from the piston slap program. This study revealed that a certain acoustic mode of the cooling water passage had a dominant effect on the amplitude of water coolant dynamic pressure induced by liner vibration. Measures of eliminating the acoustic mode are believed to be able to suspend pressure fluctuation and furthermore the potential of cavitation.
Highlights
Diesel engines are still in high demand in fields such as transportation and power generation because they are fuel-efficient, have high power density and better response to load changes and are relatively easy to maintain, but there are cases where diesel engines are damaged due to the failure of key component parts, which especially include cylinder head [1], wet liner [2], injection nuzzle [3] and piston ring [4], due to cavitation erosion.The diesel engines of large output are generally water-cooled four-stroke engines with continuous operation for a long time [5]
Cavitation is likely to occur in the water coolant around cylinders, resulting in local concentrated honeycombed pits, especially on the thrust side and antithrust side of liners; this phenomenon is called liner cavitation erosion [6,7]
Cavitation happens on the other side of liners at the lubricant oil film between piston rings and cylinder liner during the high compression stroke [8]
Summary
Diesel engines are still in high demand in fields such as transportation and power generation because they are fuel-efficient, have high power density and better response to load changes and are relatively easy to maintain, but there are cases where diesel engines are damaged due to the failure of key component parts, which especially include cylinder head [1], wet liner [2], injection nuzzle [3] and piston ring [4], due to cavitation erosion. The effect of characteristics of the acoustic field on pressure fluctuation is analyzed under different rotation speeds, indicating that a certain acoustic mode of the water coolant passage inspired by engine vibration has an important influence on pressure fluctuation and the potential of cavitation. Current development in this field lacks effective means to evaluate the potential of cavitation during the design stage. The discovery in this paper could be utilized to design coolant passages to suppress certain acoustic modes and the potential of cavitation
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