With the continuous increase in effective pressure, rotational speed, and specific power of modern diesel engines, 

along with the trend toward lighter specific mass, more compact structures, and thinner cylinder liner walls, 

their resistance to cavitation erosion has declined. In our maintenance practice, we have observed that cavitation damage 

in modern diesel engines is particularly severe. Many diesel engine cylinder liners are replaced not because they have exceeded 

the wear limit but due to cavitation damage, which forces their renewal. Cavitation erosion has become a significant factor affecting 

the service life and reliability of modern diesel generator sets.

**Formation of Cavitation Erosion**

Cavitation erosion refers to the erosion of the outer surface of a diesel engine’s wet-type cylinder liner, which is in contact with the coolant, 

resulting in the formation of needle-like pits. These pits gradually expand and deepen, eventually forming deep holes or cracks. Typically, 

these holes are clean, with no corrosion byproducts. Wet-type cylinder liners, which directly contact the coolant, 

inevitably undergo cavitation erosion over time. Even dry-type cylinder liners, though not in direct contact with the coolant, are subject to 

cavitation erosion of the liner seats. Once the liner seats are eroded into through-holes or cracks, the dry-type liners are further damaged.

It is generally believed that cavitation erosion is caused by high-frequency vibrations of the cylinder liner. 

Mechanical vibrations induce pressure fluctuations in the coolant, leading to the formation and collapse of bubbles in the coolant, 

which is the root cause of cavitation erosion. Since the coolant contains dissolved gases, when high-frequency vibrations of the cylinder 

cause localized coolant pressure to drop below a critical threshold, the dissolved gases separate from the coolant in the form of bubbles. 

These bubbles flow into high-pressure regions, where the pressure exceeds the bubble pressure, causing them to collapse violently. 

The gas in the bubble state either re-liquefies or dissolves back into the coolant, resulting in a sudden reduction in volume. 

This triggers high-speed movement of the coolant toward the bubble center, producing a water hammer effect that generates immense 

impact forces and high temperatures. This effect propagates as pressure waves at supersonic speeds in all directions. 

When these forces act on the outer surface of the cylinder liner, they cause significant impact, compression, and high temperatures. 

Under the repeated action of such forces, the outer surface of the diesel generator’s cylinder liner undergoes fatigue, gradually peeling off 

and forming pockmarks and needle-like pits, which expand progressively as cavitation erosion continues.