天然气分段喷射对双燃料发动机性能影响的研究

针对6L190柴油/天然气双燃料发动机,采用天然气分段气态直喷的喷射规律,通过改变其主预喷间隔与预喷量,利用AVL Fire软件对缸内燃烧及排放进行数值模拟研究。结果表明:天然气预喷射能够改善混合气形成质量,缩短主喷射着火滞燃期,降低缸内最大爆发压力和最高燃烧温度,减少NOX排放,优化燃烧,但若要达到良好的预喷射效果,这需要对预喷量和主预喷间隔进行优化调整。间隔角较大时,宜采用较大预喷量;间隔角较小时,预喷量宜减少;间隔角不宜过小,否则效果会适得其反。预喷量固定时,较大的间隔角有利于改善排放;预喷量较小时,排放对间隔角变化相对不敏感。

Research on the Influence of Natural Gas Multiply-Injection Laws on Dual Fuel Engine Performance

In this paper, the law of direct injection of natural gas for the 6L190 diesel/natural gas dual fuel engine are studied by using AVL Fire software to simulate the combustion and emissions of the gas by changing the distance between the main pre-spray and the quantity of natural gas injection. The results show that natural gas pre-injection improves the quality of the mixture gas, and it does shorten the ignition delay of the main injection, reduce the maximum burst pressure and the maximum combustion temperature in the cylinder, as well as reducing Nox emissions and optimizing the combustion. But to achieve a good pre-injection effect, it is necessary to optimize the pre-spray and main pre-spray interval. When the pre- spray interval is relatively bigger, more natural gas pre-injection is better; when the pre- spray interval becomes smaller, less natural gas pre-injection is better. And the pre-spray interval should not be too small, otherwise the effect will be counterproductive; for fixed pre-spray conditions, the longer interval of pre-injection is better to improve emissions, and emissions is relatively insensitive to the changes of the interval when the quantity of pre-injection is small.