Quantifying Fuel-Air Mixing at Diesel Conditions Using Rainbow Schlieren Deflectometry Technique
14:00 - 14:30
Ajay Agrawal, University of Alabama, Huntsville, AL, USA
The physical and chemical phenomena that take place during fuel injection, entrainment and mixing, autoignition, and combustion in diesel sprays still require extensive study. Global parameters such as jet penetration and spreading rates render limited information, and thus, detailed local measurements have been sought in recent years. In this research, Rainbow Schlieren Deflectometry (RSD) technique is used, for the first time, to quantify the transient fuel-air mixing process in a high-pressure reacting spray of n-heptane fuel injected into ambient air at 28 bar and 825 K. Instantaneous RSD images reveal non-reacting and reacting regions of the spray, allow identification of liquid and vapor jet regions, highlight regions where ignitable fuel-air mixtures are formed, and depict the autoignition and combustion processes. The unique capabilities of a constant pressure flow rig (CPFR) are used to conduct multiple experiments in quick succession and thus, to obtain high-quality ensemble average data in the spray. This presentation will discuss the RSD technique, and its benefits over conventional schlieren and other laser-based techniques to determine the liquid and vapor boundaries, and mixture temperature and fuel mole fraction distributions in the vapor zone across the whole field of the spray.