The Simulation And Experimental Study Of Diesel Spray Process

Fuel injection and atomization is the most important factor which affects the combustion and emission characteristic. Good atomization can help to reduce the pollution and increase efficiency of diesel combustion. For the high density of dieseal spray, so far the crushing process can't be observed directly. Mathematical models are based on assumption, which is not solid and reliable.Based on the spray study during past a few years and combined the progress of light technology, this article proposes the dieseal spray research program with X-ray phase contrast imaging. Our research team also applied the the National Natural Science Foundation of China "Dieseal Near-field Primary Atomization Mechanism Study with X-ray Phase Contrast Imaging". The main content is reasarching the near-field spray atomization under different spray pressure and nozzle geometry.As a part of the task, author took part in the design and commissioning work of X-ray phase contrast imaging. The specific work is diesel injection system commissioning,12MPa high pressure constant volume bomb design and high-pressure fuel supply system design and commissioning. At present, the system woks properly. In order to verify reliability of the system, the static spray test has been carried out.In order to study the effects of different nozzle geometry to spray, the nozzle geometry must be checked if matched the design geometry first. So the article conducted the visualization study of nozzle internal structure. Now the conventional measurement techniques can't measure the internal structure. Author and his research team took the nozzle photos with the third-generation of synchrotron radiation light source in Shanghai Synchrotron Radiation Facility (SSRF). Including the chamber, the internal structure can be seen clearly; diameter and length of the nozzle also can be accurately measured.Paper simulated and studied the spray field with the CFD software Fluent. Paper analyzed the variation of spray penetration, spray cone and Sauter Mean Diameter(SMD) under different back pressure, injection pressure and the ratio of length to diameter with discrete phase spray model in Fluent. Under the constant injection pressure back pressure decreasing, or under the constant back pressure injection pressure decreasing and the ratio of length to diameter increasing, each of them will reduce the spray penetration and increase SMD.Article features:1. By the analysis to the traditional spray test technology, combined the development of optical technology, this article proposed a series of new visualization test technologies for gas-liquid flow in nozzle, near-field and far-field of spray.2. Established a set of high pressure electronic control diesel injection system used for X-ray phase contrast imaging.3. Observed the nozzle internal structure with X-ray phase contrast imaging, pointed out the domestic nozzle processing problems.