超臨界圧雰囲気中の乱流混合層の数値解析(相変化,一般講演)

概要

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Direct numerical simulation (DNS) of a cryogenic nitrogen/nitrogen gas temporally developing mixing layer at super-critical pressures was conducted to explore turbulent mixing layers with thermodynamic transition near the pseudo-critical temperature. Flow visualization revealed that due to thermodynamic transition, the cold dense nitrogen penetrated deeply in the middle part of the mixing layer, like entrained liquid ligaments observed in liquid/gas mixing layers. Meanwhile, dominant turbulent eddies were formed in the upper region of the mixing layer, and were not directly affected by the entrainment of the dense nitrogen. Consequently, the Reynolds stress and turbulent heat flux under transcritical conditions were not directly influenced by thermodynamic transition. Reynolds-averaged Navier-Stokes (RANS) simulations were also conducted to examine the applicability of RANS methodology to turbulent mixing layers in transcritical conditions. It was indicated that by properly considering the variation of density in turbulent models, RANS methodology can simulate the turbulent mixing under transcritical conditions.
2010-09-09