Abstract
A turbocharged downsizing spark ignition (SI) engine cooperating with an in-cylinder direct injection technology is one of the most effective ways to improve the power and economy of gasoline engines. However, engine knock has limited the application and development of the downsizing of gasoline engines. Water injection technology can effectively suppress the knock. In this study, a method of numerical simulation was used to explore the effect of the water injection temperature on the combustion and suppression of the knock. First of all, the knock of the gasoline engine was induced by advancing the spark timing. Then, when the other conditions were the same, different water injection temperatures were set. The results show that lowering the water injection temperature reduced the knock intensity in the cylinder, but increasing the water injection temperature made the water distribution more uniform, and the peak values of each monitoring point were more consistent. The circulating work power increased with the increase of the water injection temperature. For emissions, as the temperature of the water injection increased, the emissions of soot and unburned hydrocarbons (UHCs) decreased, and NOx slightly increased.
Highlights
At present, improving engine performance and reducing emissions are the main directions of internal combustion engine research [1,2]
The results show that water injection can effectively improve the anti-knock resistance of fuel, and water injection can reduce the temperature in the cylinder and reduce NOx emissions
In this was induced to knock by advancing the spark timing, and
Summary
At present, improving engine performance and reducing emissions are the main directions of internal combustion engine research [1,2]. A turbocharged downsizing spark ignition (SI) engine cooperating with direct injection technology in the cylinder can effectively improve the performance of a gasoline engine. The downsizing technology will increase the maximum temperature and pressure in the cylinder, which causes engine knock. The spontaneous combustion of the terminal mixture will cause a violent chemical reaction, and the large amount of heat emitted will rapidly raise the temperature of the mixture in the surrounding area and form a pressure shockwave. Knock has become the main limiting factor for the development of downsizing technology [6,7,8]
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