Research On Cavitation Erosion Characteristic For Diesel-engine Cylinder Liner Based On FLUENT

Cavitation erosion in Cylinder liner is one of main failure mode in diesel engine used in ship. Therefore, it is significant to resolve the problem of cavitation erosion which enhances the life and guarantees economical and reliable function for diesel engine. Cavitation erosion is caused by frequency vibration of engine body and high pressure impulse of coolant. In this paper, characteristics of cavitation erosion in cylinder liner are introduced and the effecting factors on cavitation erosion are expounded. The methods to prevent cylinder liner from cavitation erosion are presented. The 2D model of cylinder liner is set up using GAMBIT software and the model is simplified. Simulation calculation of fluid flow outside cylinder liner is performed by FLUENT. Through observing variation of absolute pressure, vapor volume fraction in flow field, the mechanism of cavitation erosion in cylinder liner and effecting factors are investigated.The main results of the paper are concluded as follows: Amplitude with high frequency in cylinder liner vibration has important influence on the entire flow field. The stage of piston stroke is the main area that cavitation erosion occurs. Almost vapor bubbles vanish slowly at the pressure no higher than atmospheric pressure which are generated due to cavitation in the large vibration amplitude and dissolve in water. While absolute pressure elevating rapidly, volume fraction of this zone will decline momentarily associated with large amplitude. It shows that the vapor bubbles collapse at high pressure. The rigidness of cylinder liner wall plays a key role in vibration. Increase in liner wall thickness of cylinder will increase the rigidness, which is benefit to anti-cavitation erosion. The impact energy is decided by the tolerance clearance between piston and cylinder. The lateral vibration acceleration and the impact energy will be weakened by decreasing the clearance. It is an effective way to prevent cylinder liner form cavitation erosion. The vaporization pressure is different under different temperature. As the temperature increases, high and low pressure drop of flow field decreases and the pressure change becomes stable.