Numerical Model of Effect of Coolant Physical Properties on the Diesel Engine Liner Cavitation 2012-01-1682
Cavitation, the study of formation, growth, and collapse of vapor cavities in the coolant jacket adjacent to diesel engine cylinder liners is an area of concern for diesel engine builders and users. Prior experimental work provides insight into parameters such as temperature and pressure. A commonly used bench test has been found not to correlate well with field testing. Also, field testing is very time consuming and costly. The 250 hour engine dynamometer coolant test in the industry costs over $60,000. Therefore, use of mathematical models for sorting out coolants is used, to study effects of coolant properties such as viscosity and surface tension on liner cavitation. Jet velocity at the time of implosion of the bubble is considered as a mechanism to quantify cavitation damage potential near a rigid wall. A model calculating jet velocity at the time of bubble collapse near a finite plate is determined using a commercial boundary element code, 2DynaFS. Testing of the models is achieved by comparing effects of typical coolants such as 100% water, 40, 50, and 60% mixtures of ethylene glycol with water and 40, 50, and 60% mixtures of propylene glycol with water. Potential of cavitation damage correlated to jet velocity showed good agreement with the published results . Increased viscosity greatly reduced the jet velocity and thereby the cavitation potential, while surface tension showed very little effect. The nucleation process, i.e. initialization of the bubble, is not modelled in the scope of this paper, where the effect of surface tension plays important role.