柴油机喷油器各孔介观高压喷油及喷雾特性研究

There are complicated dynamic behaviors in multiphase flows in meso-scale. The surface characteristics of the surface in touch with fuel inside the injector has significant influence on the fuel flow, fuel injection and spray characteristics. There are differences in the injection characteristics of each nozzle hole or different injectors due to the structure and machine process even if they have the same size. The uniformity of injectors is difficult to guarantee. The surface characteristics inside the injector will change as result of the hydro-grinding of the fuel with high pressure in used injectors. The combustion and emission performance of diesel engine are influenced significantly by the injection and spray characteristics. 3D model of fuel flow inside the nozzle and spray model which considers the influence of the fuel injection are established to investigate the influence of surface characteristics inside the injector on the fuel flow ,cavitation, injection and spray characteristics of each nozzle hole. The fuel injection rate and flow coefficient of each nozzle hole in different surface characteristics nozzle are measured by the transient momentum method. The visualization test bench for spray is set up. The influences of different surface characteristics of injectors,pump speed,fuel injection quantity,injection pressure,etc. on the fuel flow,cavitation,fuel injection and spray characteristics （spray angle,spray pentration,SMD,concentration,etc.）of each nozzle hole is investigated to provide principle for the injector design,manufacture and quality control.

介观尺度多相流动涉及复杂的接触动力学特征。在喷油嘴内部，与燃油接触的零件内表面特性对燃油流动、喷油及喷雾特性有重要影响，名义尺寸相同的喷油器由于结构及加工等原因，各喷油器及各喷孔喷射特性存在差异，一致性较难控制，喷油器长时间使用后，由于高压燃油的液力研磨作用，喷油器内表面特性发生变化，其喷油及喷雾特性的也会变化，从而影响柴油机的燃烧和排放等性能。建立用介观尺度描述的粗糙度模型,建立考虑喷油嘴内零件表面特性影响的燃油流动三维模型和考虑喷射特性影响的燃油喷雾特性三维模型，研究喷油嘴内表面特性对喷油嘴内燃油流动、空化现象、各孔喷射特性和喷雾特性的影响;用动量法测量不同内表面特性喷油器各孔喷油规律和流量系数;搭建高压喷雾可视化试验台，研究喷油嘴内表面特性及转速、循环喷油量、喷油压力等对燃油流动、空化现象、各孔燃油喷射特性和喷雾特性（喷雾锥角、贯穿距离、索特平均直径、浓度场等）的影响。为喷油器设计制造及质量控制提供指导。

介观尺度多相流动涉及复杂的接触动力学特征。在喷油嘴内部，与燃油接触的零件内表面特性对燃油流动、喷油及喷雾特性有重要影响，名义尺寸相同的喷油器由于结构及加工等原因，各喷油器及各喷孔喷射特性存在差异，一致性较难控制，喷油器长时间使用后，由于高压燃油的液力研磨作用，喷油器内表面特性发生变化，其喷油及喷雾特性的也会变化，从而影响柴油机的燃烧和排放等性能。建立了考虑六孔及八孔喷油嘴内零件表面特性影响的燃油流动三维模型和考虑喷射特性影响的燃油喷雾特性三维模型，研究喷油嘴内表面特性对喷油嘴内燃油流动、空化现象、各孔喷射特性和喷雾特性的影响;用动量法测量不同内表面特性喷油器各孔喷油规律和流量系数;搭建高压喷雾可视化试验台，研究喷油嘴内表面特性及转速、循环喷油量、喷油压力等对燃油流动、空化现象、各孔燃油喷射特性和喷雾特性（喷雾锥角、贯穿距离、索特平均直径、浓度场等）的影响。研究结果表明，由于液力研磨后表面粗糙度控制在很小范围内，喷油嘴内表面特性对各孔喷射特性影响不大。各孔喷射特性存在差异的主要原因之一是针阀间隙及其受力变形和偏心运动。为喷油器设计制造及质量控制提供指导。发表SCI论文7篇（其中一区2篇、二区四篇），另有1篇SCI期刊已录用，获得授权发明专利2项，毕业博士三人（其中海外留学生一人）、硕士2人。