516 / 2018-12-31 21:31:22
喷射正时对电热塞引燃式直喷甲醇发动机的影响研究
甲醇;发动机;喷射正时;燃烧;排放
摘要录用
喷射正时与内燃机缸内燃料空气混合气的形成有着密切的联系,进而通过起燃点影响发动机的动力性和排放性。受甲醇性质以及喷射技术的限制,以往关于甲醇发动机的研究和应用均在低喷射压力下进行。随着燃料喷射系统技术的进步以及高性能氮化硅电热塞的研制,使得电热塞引燃式高压直喷甲醇发动机在应用中成为可能。本文基于电热塞引燃式直喷纯甲醇发动机建立3D CFD模型,在喷射压力为60MPa下,研究了喷射正时对甲醇雾化、空燃混合、燃烧以及排放等的影响。研究表明:引燃甲醇空气混合气的火核形成于电热塞端部,而且火焰传播呈现出与柴油机和汽油机不同的规律。处于靠近电热塞一端的燃烧室凹坑中的可燃混合气首先被燃尽,而后火焰向外部传播。喷射越晚,发动机指示功率越低;在排放物方面,喷射越晚,膨胀行程中积累的甲醛的含量越高。在所研究的喷射正时范围内,喷射正时对燃烧废气中CO含量的影响未表现出明显的规律性。
Injection timing is closely related to the formation of fuel-air mixture and plays an important part in combustion and emission of direct injected methanol engine. Limited by the properties of methanol and injection technology, previous studies and applications of methanol engines have been carried out at low injection pressures. With the development of fuel injection technology and high-performance silicon nitride plug, it is possible of the application of electrothermal plug ignited direct injection methanol engine at high pressure. In this study, an electrothermal plug ignition direct injection pure methanol engine based on hot surface ignition is adopted. With a 3D engine cylinder model, the effects of injector pressure on methanol atomization, air-fuel mixing, combustion and emission are studied. The results show that the breakup and atomization of methanol droplets, the uniformity of combustible mixture and the decrease of mean temperature in combustion are influenced by the injection timing. With a electrothermal glow plug to ignite methanol in engine, the ignition position is located at the end of the electric plug. It is shown that the flame propagation is different from that of diesel engine and gasoline engine. The combustible mixture in the combustion chamber pit near the end of the electric plug is burnt out first, and then the flames spread to outer space under high injection pressure. The later the injection, the lower the indicated power of the engine. In terms of emissions, the later the injection, the higher the formaldehyde content accumulated during the expansion. In the range of injection timing studied, the effect of injection timing on CO content in combustion exhaust gas shows no obvious regularity.
(作者单位:同济大学机械与能源工程学院 通讯地址:上海市嘉定区曹安公路4800号)
重要日期
  • 会议日期

    10月21日

    2019

    10月25日

    2019

  • 10月20日 2019

    初稿截稿日期

  • 10月25日 2019

    注册截止日期

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