【作者】 王洪涛；

【导师】 许沧粟；

【作者基本信息】 浙江大学 ， 动力工程（专业学位）， 2016， 硕士

【摘要】 生物乙醇是目前世界上应用最为广泛的生物质燃料之一,特别是随着新一代乙醇制取技术的发展使得其应用前景更为广阔。而激光点火技术作为车用发动机点火系统的研究也日益广泛,主要是因为激光点火具有点火能量密度高,点火位置可调,可较容易实现多点点火等因素。为了更好地将激光点火技术与生物乙醇的优势结合起来,本文研究初始温度和压力分别为358 K和0.1 MPa的乙醇-空气预混合气激光点火时的燃烧特性,详细研究层流燃烧速度、马克斯坦长度等预混燃烧特性,并与中心电极点火时的预混燃烧特性进行了比较。第一,在初始温度和压力分别为358 K和0.1 MPa试验条件下,在温控定容燃烧弹上用高速纹影成像系统记录了当量比0.6—1.6的乙醇空气预混合气激光点火时的类球形火焰发展过程,并且用压电式压力传感器测量容弹内的压力,压力信号经电荷放大器放大后,用数字示波器记录容弹内压力变化曲线。在火焰半径的提取过程中提出了Photoshop像素转换法,并与传统的夹逼法等测量方法做比较,以确定Photoshop像素转换法的正确性。确定火焰半径变化后,对比使用线性外推法和非线性外推法计算了层流燃烧速度,发现用非线性外推法得到的层流燃烧速度能更真实反映火焰传播过程中的速度,并分析了质量燃烧速率,马克斯坦长度,峰值压力,已燃质量分数,放热量等预混燃烧特性参数。第二,文中对激光点火火焰扩展过程做了较为全面的总结,特别是等离子体形成过程。另外文中对激光点火和中心电极点火的层流燃烧速度,压力变化和已燃质量分数做了比较,试验表明在稀燃条件下,激光点火层流燃烧速度高于中心电极点火。更多还原

【Abstract】 With the development of the new production technology of ethanol, Bio-ethanol has become one of the most widely used biomass fuels in the world. In the meantime, laser ignition technology as the vehicle engine ignition system is increasingly widespread because of its higher ignition energy and adjustable ignition position. Moreover, laser ignition can easily achieve multi-point ignition. In order to take full advantage of laser ignition and bio-ethanol, for the initial pressure and temperature were 0.1 MPa and 358 K respectively, we researched the flame characteristics of ethanol-air ignited by laser, such as the laminar burning velocity. Simultaneously, combustion characteristics under different ignition system were compared.1. Ethanol-air mixtures ignited by laser were researched by using constant volume combustion chamber. High speed schlieren imaging system was used to record flame development process at different equivalence ratios 0.6-1.6 and the pressure curve in the chamber was recorded by using the charge amplifier and digital oscilloscope. In the extraction process of flame radius, the Photoshop pixel conversion method was proposed and compared with the traditional double sides approximate process to verify the correctnesss of Photoshop pixel conversion method. The linear extrapolation and nonlinear extrapolation method were used to calculate the unstretched laminar propagation velocity. Then, other combustion characteristics, such as mass combustion flux, Markstein length, peak pressure, fuel mass fraction, heat release rate and so on, were analyzed.2. A comprehensive summary of the laser ignition process was summarized, especially the formation process of the plasma. In addition, flame combustion characteristics including laminar burning velocity, pressure and fuel mass fraction by laser ignition and central electrode ignition were compared. We found that under lean burn conditions, laminar burning velocity by laser ignition is higher than that of the central electrode ignition.更多还原