采用示踪激光诱导荧光方法进行喷雾燃烧诊断

To understand and optimize the combustion processes in new types of internal combustion engines, like gasoline direct-injection engines, non-intrusive laser-based diagnostics methods have proven to be versatile and important tools to measure combustion characteristics. Most engine developers already rely on optical methods in the development of new engines. To guarantee accurate and reliable results of optical measurements it is necessary to carefully evaluate and characterize these techniques under realistic conditions. In this work a variety of laser-based diagnostics techniques, mostly based on the tracer- LIF principle, have been evaluated for their applicability and limitations and have been applied to different spray systems – reaching from single droplets, over model sprays to fuel sprays in a firing test engine. The tracer-laser-induced-fluorescence (LIF) method is based on doping the fuel with a fluorescent substance whose fluorescence characteristics are used to measure various physical properties of the spray, such as temperature, droplet size, or droplet velocity. From these properties information about heat and mass-transfer mechanisms in the spray can be gained. However, the characteristics of the used tracers must be known in detail in order to guarantee useful and comparable results. Therefore, in this work various tracers were characterized in terms of their evaporation and temperaturedependent properties. The tracers Atto 680, Rhodamine 800 and Rhodamine B have further been tested for their applicability to realistic fuels.