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Indexed by:期刊论文

Date of Publication:2017-01-01

Journal:HEAT TRANSFER RESEARCH

Included Journals:SCIE、EI、Scopus

Volume:48

Issue:17

Page Number:1545-1565

ISSN No.:1064-2285

Key Words:large eddy simulation; transcritical and ideal-gas jet; real-fluid effect; pseudoboiling; turbulent mixing

Abstract:Cryogenic nitrogen injected into a supercritical environment is numerically studied by large eddy simulation to explore the influence of pseudoboiling on the jet evolution and mixing process. For comparison, the same model is simulated in ideal-gas conditions with the same initial profiles of density and velocity. The results show that the turbulent kinetic energy and vorticity distributions in both cases are nearly the same indicating that the dominant eddies and the production and dissipation of the turbulent kinetic energy are not directly affected by the pseudoboiling phenomenon. Moreover, the axial velocity distributions in the two cases are also similar, revealing that the pseudoboiling has little effect on turbulent transport mechanisms. However, the density distribution is evidently influenced by the pseudoboiling. Because of the existing of pseudoboiling effects, the most thermal energy absorbed from the surroundings is spent to expand the jet volume, rather than to increase its temperature, so the transcritical fluid is entrained deeply along the axial and radial directions. As a result, before the pseudocritical temperature is reached, the mean profiles of axial and radial density distributions change more slowly in comparison with the ideal-gas condition. Consequently, the mass transport mechanism is considered to be influenced by the pseudoboiling under transcritical conditions.