二/四冲程可变柴油机燃烧室热负荷的改善  

Optimization on thermal load of combustion chamber on two/four-stroke switchable diesel engine

作　　者：张岩[1] 刘玮[1] 张树勇[1] 裴毅强[2] 董蒙蒙 秦静[2,3] ZHANG Yan;LIU Wei;ZHANG Shu-yong;PEI Yi-qiang;DONG Meng-meng;QIN Jing(National Key Laboratory of Diesel Engine Turbocharging,China North Engine Research Institute,Tianjin 300072,China;State Key Laboratory of Engines,Tianjin University,Tianjin 300072,China;Internal Combustion Engine Research Institute,Tianjin University,Tianjin 300072,China)

机构地区：[1]中国北方发动机研究所柴油机增压技术重点实验室,天津300072 [2]天津大学内燃机燃烧学国家重点实验室,天津300072 [3]天津大学内燃机研究所,天津300072

出　　处：《吉林大学学报（工学版）》2022年第3期504-514,共11页Journal of Jilin University:Engineering and Technology Edition

基　　金：国家自然科学基金项目(51606175).

摘　　要：采用计算流体动力学(CFD)方法对一台二/四冲程可变柴油机在二冲程工作模式下活塞烧蚀的现象进行了研究,分析发现气流运动导致混合气在活塞碗沿处发生燃烧,从而产生了局部高温和局部过高热负荷。设计了两种燃烧室结构形式,通过调整油-气-室的配合以改善燃烧状况,研究发现,增大燃烧室碗口直径可以减少向活塞碗沿上方扩散的混合气,增大混合气在燃烧室内部的扩散空间,从而避免了在活塞碗沿处产生过高热负荷;增大燃烧室凹坑直径则有助于在凹坑内产生涡流,促进混合气的形成,缩短燃烧持续期。模拟计算结果显示,相比于原机,在2800 r/min@46 kW工况下两种优化设计的燃烧室在活塞碗沿上的热负荷得到明显改善,功率分别提高了4.11%和1.96%。加工设计一方案并在相同工况下进行对比试验,结果表明,相对于原机,优化设计后的柴油机油耗降低了6.93%,排气温度降低了21.1 K,活塞表面状态良好,无烧蚀发生。The in-cylinder combustion process of a two/four-stroke switchable diesel engine at high load conditions under two-stroke working mode was analyzed based on the three-dimensional CFD simulation.It was found that the movement of airflow causes the mixture to burn at the edge of the piston bowl,resulting in local high temperature and local excessive thermal load. Two optimized designs of combustion chambers were obtained to adjust the match of oil and gas with chamber to improve combustion. It was found that increasing the diameter of combustion chamber expands the diffusion space of the mixture and reduces the mixture diffused above the piston bowl edge,which can avoid excessive thermal load at the piston bowl edge. Increasing the diameter of the piston pit helps produce the vortex in the pit to promote the mixture formation and shorten the combustion duration. The thermal loads of the piston bowl edge of these two designs are significantly improved,and the combustion durations of the chamber Ⅰ and chamber Ⅱincrease the power by 4.11% and 1.96% respectively. The comparison test of the original machine and chamber Ⅰ was carried out under the ablation condition of the original machine at 2800 r/min@46 kW.Compared with the original machine,the fuel consumption of the chamber Ⅰ is reduced by 6.93%,exhaust temperature is decreased by 21.1 K and the piston surface is smooth without any ablation.

关 键 词：动力机械工程 二/四冲程可变柴油机 热负荷 燃烧室设计 

分 类 号：TK421.2[动力工程及工程热物理—动力机械及工程]