Simulation Study on the Effect of In-cylinder Water Injection Mass on Diesel Engine Combustion and Emissions

Based on Caterpillar 3401 diesel engine, a complete three-dimensional model of the combustion chamber was established in CONVERGE to study the effect of in-cylinder water injection on combustion characteristics and emissions within the water injection mass rang from 5mg to 100mg. With the water mass increase, the pressure, power and temperature in the cylinder increase first and decrease later. The changes of CA5 and CA10 of the heat release are not obvious. CA50 of the heat release advances first and delays later. The combustion duration shortens first and increases later. NOx emission is increases as the water injction mass increases from 5mg to 40mg, but it is decease when the water injction mass increases from 40mg to 100mg. And when the mass of water is 100mg, it has the best suppression effect on NOx. Otherwise, the water injection has the best suppression effect on Soot when the water mass is 60mg.