High Pressure Optical Chamber for Fuel Injection and Spray Study

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In-depth understanding of fuel sprays becomes very important in clean combustion modes, such as diesel low temperature combustion (LTC). In diesel LTC, it is essential to form a lean, diluted and homogeneous cylinder charge in order to achieve low combustion temperatures and thus simultaneously ultra-low soot and nitrogen oxides (NOx) emissions. In the heterogeneous regions of the mixture, high temperature combustion prevails and leads to soot and NOx emissions. It is more important to enable biofuel clean combustions in diesel engines maintaining high efficiency. The fuel spray development is critically attributed to the impacts on the air-fuel mixture homogeneity. Sophisticated injection pressure and timing controls have been developed in PI's research to improve the fuel/air mixing effectively. For instance, with modern common rail injection systems, diesel fuel is injected at upstream pressure levels to 700~2200bar. Such elevated injection pressure is sought to enhance the fuel atomization and evaporation and to improve the fuel spray quality. Additionally, multiple-shot early injection strategies are generally applied to achieve homogeneous compression ignition. Thus, it will be very critical and cost effective for injection control and strategy development if the distribution and characteristics of the injected fuel are known at specific time or crank angle, particularly for biofuel and multi-fuel studies. It is a privilege to perform detailed quantitative evaluation and quality analyses using laser and high speed imaging technologies with a visually accessible chamber. The requested equipment is an EFS InjetVision Chamber system that can simulate the in-cylinder pressure of diesel engines with injection events. The system can be seamlessly integrated into our existing EFS injection testing bench. When spray tests are carried out in such an optical chamber, the injected fuel sprays can be clearly recorded with high speed camera from different viewing angles, making it feasible to quantitatively analyze the spray geometries in 2D and 3D. The injection process can be manifested by the time-resolved images. The optical analyses will cast light on the fuel distribution, atomization, and its mixing with air.