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Browsing by Issue Date, starting with "2012-08-22"

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  • Numerical simulation of an array of droplets through a crossflow
    Publication . Barata, Jorge M M; Cometti, A.; Mendes, António; Silva, André
    This paper describes the application of a three-dimensional computational method based on the solution of the Reynolds-averaged Navier-Stokes equations and a SSF (stochastic separated flow) model to the problem of an array of droplets through a crossflow. The calculation method is first evaluated against measurements for two-phase axisymmetric jets, and then extended to the three-dimensional case. The influence of the droplet sizes on the dispersion phenomena is analyzed. The exchange of momentum and turbulence energy was shown to play a decisive role in the change of the gaseous flow velocities. The analysis of the source terms due to the droplets revealed a strong influence of the boundary layer near the injection point in the dispersion process.
    2012-08-22Journal article Embargoed access Show more
  • Numerical study of cryogenic jets under supercritical conditions
    Publication . Barata, Jorge M M; Gokalp, Iskender; Silva, André
    The present work is devoted to the study of cryogenic nitrogen jets in sub- and supercritical conditions. A general trend to operate under an increasingly higher combustor pressures is observed in rockets, gas turbines, and diesel engines, primarily due to enhanced effects on thrust, power, or efficiency. In this conditions, the injected fluid(s) may experience ambient pressures exceeding the critical pressure(s) of the propellants, and recent experimental work of Chehroudi et al.1 showed a quantitative similarity to gas jet-like behavior This paper reports an investigation aimed to evaluate the capabilities of a computational method developed for incompressible but variable density flows when applied to supercritical conditions. The predicted initial jet growth rate was compared with available experimental data for liquid/gaseous jets and mixing layers, and showed a good agreement for different density ratios.
    2012-08-22Journal article Embargoed access Show more