Atomization and Sprays Journal of the International Institutes for Liquid Atomization and Spray Systems

ISSN for PRINT: 1045-5110

For Online Access

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2006, Volume16

Issue 5

128 pages

DOI: 10.1615/AtomizSpr.v16.i5

Issue price - $80.00

Chang Sik Lee
Department of Mechanical Engineering, Hanyang University, 17 Haengdang-dong, Sungdong-gu, Seoul 133-791, Korea

Ki Hyung Lee
Department of Mechanical Engineering, Hanyang University, 1271 Sa 1-dong, Ansan, Kyunggi-do 425-791, Korea

Rolf D. Reitz
Engine Research Center, University of Wisconsin-Madison, 1500 Engineering Drive, Madison, WI53706, USA

Sung Wook Park
Graduate School of Hanyang University, 17 Haengdang-dong, Sungdong-gu, Seoul 133-791, Korea

This article describes the effects of split injection on the macroscopic behavior and atomization characteristics of a high-speed diesel spray injected through a common-rail system. In order to reveal the effects of the first injection on the second injection under various injection durations, experiments on the injection rate, spray behavior, and drop Sauter mean diameter (SMD) were conducted by using an injection rate meter, a spray visualization system, and a phase Doppler particle analyzer system. The test injector had a single hole with 0.3 mm hole diameter and 0.8 mm nozzle length. In split injections, the sum of the first and second energizing durations was set constant as 1.2 ms, and various split injections were studied. The effect of ambient pressure on the spray development was also investigated by using a high-pressure spray chamber. For the numerical investigations, the KIVA-3 code including a modified nozzle flow model, and a breakup model was applied to the simulation of spray atomization using the same calculation conditions as the experiments. The injection velocity was calculated based on the flow model that considers cavitation in the nozzle and the realistic nozzle geometry. The breakup model, which has a dominant effect in calculating the mean droplet size of the spray, was also modified to include the Kelvin-Helmholtz instability/droplet deformation and breakup (KH-DDB) model. In the KH-DDB model, both wave instability and droplet deformation are considered as the breakup factors upstream of the jet breakup length. On the other hand, beyond the breakup length, only droplet deformation is regarded because the relative velocity between the droplet and the ambient gas is lower in comparison to the velocity above the breakup length. The results show that the effect of interference between injections on the injection pressure is little in comparison to the effect of gas flow. The entrainment of ambient gas by the first injection causes a longer spray tip penetration and larger drop SMD for the second injection in comparison to the case of a single injection.

DOI: 10.1615/AtomizSpr.v16.i5.50 Download article, 543-562 pages

Article price - $35.00

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