以 AVL程序为计算平台,采用 Boost和 Fire软件分别建立柴油机一维和三维仿真模型进行模拟计算,利用 Miller循环和 EGR技术来降低缸内燃烧温度,并通过燃烧室和涡流比的合理匹配来改善缸内的油气混合,从而减少排放物生成,满足越来越严格的排放法规.结果表明,随进气门关闭正时的提前,缸内温度逐渐降低, NOx排放减小,但进气门关闭过早会增加NOx排放;燃烧室结构的优化并匹配合理的初始涡流比能够改善缸内流动,进一步减少排放,增加指示功率;EGR策略可以弱化缸内高温分布,减少 NOx排放,但碳烟排放有所增加.采用改进的燃烧室和涡流比并匹配Miller循环和EGR技术可使NOx排放降低96.5%,,同时使功率输出略有增加.%In order to meet more and more stringent emission regulation,numerical study was conducted to inves-tigate the temperature reduction effect of Miller cycle coupled with intake turbocharging system and EGR(exhaust gas recirculation)as well as the better fuel-air mixing effect of combustion chamber modification and initial swirl ratio based on AVL Boost and Fire.The results show that with the advance of Miller timing,the temperature in cylinder decreases,and the NOxemissions decrease as well,while the premature intake valve close timing in-creases NOxemission.The modification of combustion chamber and reasonable initial swirl ratio can improve the fuel-air mixing inside the cylinder,reduce emissions and increase the indicated power.EGR strategy can evidently reduce high temperature distribution and NOxemission,while soot emission increases.The optimization of Miller cycle,combustion chamber,initial swirl ratio and EGR can reduce NOxemission by 96.5% and slightly increase output power.
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