The mechanism of combustion in diesel engines is strongly determined by the structure of the jet issuing from the injector; the actual flow being two-phase, unsteady and compressible with further features of turbulence and three-dimensionality, a direct attack by means of powerful numerical techniques can often proove to be unsuccessful or economically unaffordable. A semi-empirical method, based on the extension in the time domain of the classical theory of turbulent jets, has been developed in order to get a better insight of the physical phenomenon; the applicability of the approach to unsteady jets as encountered in engine fuel injectors has been checked and theoretically justified, and the integration in time of the equation of continuity and momentum conservation allows to calculate instantaneously the jet penetration from the input data, consisting in the time-history of the injection pressure. An experimental setup has been assembled in order to check the results of the analysis: an injection pump was mounted on an injector test bench, and one of the injectors was instrumented for the fast-response measurement of the injection pressure, needle displacement and jet penetration. The instrumentation, comprising quartz pressure transducers, a capacitive gap sensor and a conical hot film probe, was connected to a data acquisition system providing a direct microcomputer interface for data collection and handling; on the same computer the program for the calculation of the jet penetration was run. The measurements have allowed to assess the good performance of the simulation in predicting the jet penetration.

Media Info

  • Features: Figures; References;
  • Pagination: p. 503-511

Subject/Index Terms

Filing Info

  • Accession Number: 00399906
  • Record Type: Publication
  • Source Agency: National Highway Traffic Safety Administration
  • Report/Paper Numbers: ISATA 84029, HS-038 447
  • Files: HSL, USDOT
  • Created Date: Oct 31 1985 12:00AM