【摘要】 针对重型柴油机高效率、高清洁和高可靠性的多目标需求,从燃烧系统、排放后处理系统和关键摩擦副等三个关键环节入手,从系统层面提出了设计参数优化与控制参数优化相结合的全局协同优化思路,通过计算流体动力学(CFD)仿真、虚拟标定和试验优化的全流程有机衔接,有效解决了多项新技术在目标机型上的快速集成问题.研究表明:通过综合采用米勒循环、两级增压、大流量俯冲组合气道与分段卷吸燃烧室相结合的燃烧技术,以及基于优化混合结构的选择性催化还原(SCR)、气门坐圈减磨、活塞环岸优化设计和缸套分区润滑等多项技术及其协同优化,所开发的重型柴油机在整机排放达到国Ⅵb标准的条件下,最低燃油消耗率低至174.8 g/(kW·h),气门间隙调整周期突破5 000 h,缸套磨损寿命延长25%,整机倒拖摩擦功耗下降5%.更多还原

【Abstract】 Based on multi-objective requirements of high efficiency,low emissions and high reliability of heavyduty diesel engines,a system-level optimization of design parameters and control parameters was conducted mainly focused on combustion system,exhaust after-treatment system and friction reduction of key moving parts. By using comprehensive optimization methods including computational fluid dynamics(CFD) simulation,virtual calibration and engine design of experiment(Do E) test,several new technologies were rapidly integrated into the engine and effectively matched each other to realize the multi-objective requirements. Experimental results show that the heavy-duty diesel engine achieves China Ⅵb emission standard through the combining use and comprehensive optimization of Miller cycle,two-stage turbocharger,high-flow-coefficient direct intake ports,stepped-lip reentrant combustion chamber,as well as efficient selective catalytic reduction(SCR) mixer,valve seat wear reduction,piston ring optimization design and partition lubrication of the cylinder liner. In addition,the best fuel consumption rate reaches 174.8 g/(k W·h),the valve clearance adjustment cycle extends over 5 000 h,the wear life of cylinder liner is prolonged by 25% and the friction work loss is reduced by 5%.更多还原