Quantitative Three Dimensional Measurement of Fuel Vapor Concentration via Silicone Oil Particle Scattering Imaging Method

为了弄清内燃机燃油蒸汽分布与燃烧特性之间的关系，分别采用激光片散射法和快速响应FID法测量了瞬时燃油喷雾和模拟分层充气燃烧的定容燃烧室中的燃油蒸汽分布，并将新的成像技术--硅油颗粒散射成像(SSI)技术应用于蒸发式瞬时喷雾的二维和顺序可视化。该方法以悬浮在燃料蒸气中的残留硅油颗粒作为散射示踪剂，用一束铜蒸气激光照射硅油颗粒的散射，用一台成帧速度为20000fps的高速图像转换相机进行成像。结果表明，蒸发喷雾中浓淡混合物团簇的间歇性和周期性运动类似于自由瞬变气体射流中的旋涡运动，为了研究混合气浓度的不均匀性对分层充量燃烧系统燃烧的影响，利用精心控制的实验系统研究了这些影响。研制了一种恒容药室，该药室可以通过在药室内设置移除隔板来模拟理想分层药包。流动和燃烧特性通过示压分析、纹影照相、离子探针测量和使用快速响应FID技术的局部当量比测量来检验，同时改变隔板两侧初始当量比的燃烧。结果表明，浓侧当量比对分层装药混合气的燃烧特性影响较大，燃烧速度较均质装药情况有所提高。

To make clear the relation between the distribution of fuel vapor and the combustion characteristics in I.C.engines, the fuel vapor distributions in a transient fuel spray and in a constant volume chamber which can simulate the stratified charge combustion are measured by a laser sheet scattering technique and by a fast response FID method respectively.The new imaging technique, which is called as silicone oil particles Scattering Imaging (SSI) method, is applied on an evaporating transient spray for visualizing the fuel vapor two dimensionally and sequentially. In this method, the residual silicone oil particles suspended in fuel vapor are used as the scattering tracers, and the scattering from the silicone oil particles which are illuminated by a sheet of light of copper vapor laser is imaged by a high speed image converter camera with a framing speed of 20,000fps. The results make clear that the intermittent and periodical motion of rich mixture cluster in an evaporating spray is similar to that of vortices in a free transient gas jet.To investigate the effects of inhomogeneity of mixture concentration on the combustion in stratified charge combustion system, these effects are examined using a carefully controlled experimental system. A constant volume chamber, which can simulate an idealized stratified charge by using a removal partition inside the chamber, is developed. Flow and combustion characteristics are examined by indicated pressure analysis, Schlieren photography, ion probe measurements and local equivalence ratios measurements using the fast response FID technique while varying the combustion of initial equivalence ratios on each side of the partition. As a result it is clarified that the combustion characteristics of stratified charge mixtures are strongly effected by rich side equivalence ratio and the combustion speed is enhanced compared to homogeneous charge case.