High-pressure, high-speed fuel sprays are a critical technology for many applications including fuel injection systems, where the structure and dynamics of the fuel sprays are the key to increasing fuel efficiency and reducing pollutants. But because liquid sprays are difficult to image, particularly in the region close to the nozzle, high-pressure fuel sprays have never been considered as supersonic under typical fuel injection conditions.
At SRI-CAT (Advanced Photon Source) and the Cornell High Energy Synchrotron Source, synchrotron x-radiography and a fast x-ray detector were used to record the time evolution of transient fuel sprays from a high-pressure injector, capturing the propagation of spray-induced shock waves in a gaseous medium and revealing the complex nature of the spray hydrodynamics. The x-radiographs also allow quantitative analysis of shock waves that is nearly impossible with optical imaging. Under injection conditions similar to those found in operating engines, the fuel jets can exceed supersonic speeds and result in gaseous shock waves. This work sets the stage for study of the entire range of fluid dynamics inside and close to high-pressure liquid sprays. The methods used here may also be applied to the characterization of highly transient phenomena in optically dense materials.
Andrew G. MacPhee(1), Mark W. Tate (3), Christopher F. Powell (1), Yong Yue (2), Matthew J. Renzi (3), Alper Ercan (3) Suresh Narayanan (1), Ernest Fontes (4), Jochen Walther (5), Johannes Schaller (5), Sol M. Gruner (3,4) Jin Wang (1)
See: A.G. MacPhee et al., Science 295, 5558, 1261-1263 (2002) (and also C. F. Powell et al., J. Synchrotron Rad.7, 356-360, ).
The Advanced Photon Source is funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Argonne Nationasl Laboratory is a U.S. Department of Energy laboratory operated by The University of Chicago.
This work was supported by the U.S. Department of Energy under contract W-31-109-ENG-38, the Freedom CAR Program, and grants DE-FG-0297ER14805 and DE-FG-0297ER62443. CHESS is supported by the U.S. NSF and the NIH under award DMR-9713424.
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