扫气式预燃室射流点火燃烧特性的实验研究  

Investigation of the effects of the scavenged prechamber turbulent jet ignition on the carbon dioxide diluted combustion

作　　者：钟力嘉 宋运通 刘沛林 周磊[1] 卫海桥[1] ZHONG LiJia;SONG YunTong;LIU PeiLin;ZHOU Lei;WEI HaiQiao(State Key Laboratory of Engines,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学内燃机燃烧学国家重点实验室,天津300072

出　　处：《中国科学：技术科学》2023年第12期2079-2089,共11页Scientia Sinica(Technologica)

基　　金：国家杰出青年科学基金项目(批准号:51825603);天津市自然科学基金项目(编号:20JCYBJC01110)资助。

摘　　要：低碳燃烧概念的出现使得内燃机节能减排势在必行.废气再循环稀释燃烧作为一种提高热效率、降低排放的技术手段,有很大的应用价值.本文针对废气稀释下燃烧不稳定问题,提出一种扫气式TJI装置.基于可视化定容燃烧弹研究了火花塞点火SI、被动式TJI和扫气式TJI在不同CO_(2)浓度下的射流及火焰发展过程.研究发现TJI能够形成较强的湍流燃烧,相较于SI有更快的燃烧速率.随着二氧化碳浓度的升高,火焰传播速度下降.TJI的射流出现时刻大幅推迟、射流强度逐渐降低,主燃室燃烧速率下降.通过对预燃室进行主动扫气可以改善预燃室内混合气状态,使得预燃室混合气在点火后燃烧速度加快,且射流强度不受二氧化碳浓度的影响,从而加快主燃室内的燃烧,拓展二氧化碳掺混极限.预燃室内当量比为1时射流强度最大.扫气模式下,二次扫气能更彻底地改善预燃室内混合气状态.相较于一次扫气更能提高射流强度,从而加快主燃室内燃烧.采用二次扫气策略可以提升主燃室稳定燃烧二氧化碳浓度极限至30%.With more attention focused on low-carbon combustion,energy saving and emission reduction of internal combustion engines have become an industry consensus.The exhaust gas recirculation(EGR)technique has a good application value in the research on lowcarbon engines in the future.However,unstable combustion often occurs in gasoline engines while they are under a high EGR rate.Turbulent jet ignition(TJI)can improve the lean-burn stability of the engine and expand the diluted combustion limit.Based on the visualization of the constant volume combustion bomb,the jet and flame development at different EGR rates under spark ignition(SI),passive TJI,and scavenged TJI are investigated.Results showed that TJI ignites the main chamber through hot jets,which can form strong turbulent combustion.Compared with SI,TJI has a faster combustion rate.As the CO_(2) concentration increases,the flame propagation speed decreases,the jet appearance from the prechamber is considerably delayed,and the jet intensity gradually decreases,which leads to a lower combustion rate of the main chamber.By actively scavenging the prechamber with air and reducing the residual exhaust gas within the prechamber,the state of the mixture in the prechamber can be improved so that the combustion rate within the prechamber is accelerated after ignition.Moreover,the jet intensity is not largely affected by the EGR rate,thereby accelerating the combustion in the main chamber and extending the EGR limit.In the scavenged TJI mode,the twice scavenging strategy can achieve a more thorough removal of the exhaust gas that remained in the prechamber.Compared with that of the once scavenging strategy,the jet intensity of the twice scavenging strategy can be improved,thereby accelerating the combustion in the main chamber.

关 键 词：射流点火 扫气式预燃室 稀释燃烧 废气再循环 

分 类 号：TK401[动力工程及工程热物理—动力机械及工程]