Direct numerical simulation of fully-developed supersonic turbulent channel flows with dense vapors

被引:1
作者
Chen, Tao [1 ]
Yang, Bijie [1 ,2 ]
Martinez-Botas, Ricardo [1 ]
机构
[1] Imperial Coll London, Dept Mech Engn, Exhibit Rd, London SW7 2AZ, England
[2] Loughborough Univ, Dept Aeronaut & Automot Engn, Loughborough LE11 3TU, Leics, England
关键词
PRESSURE-FLUCTUATIONS; BOUNDARY-LAYERS; HEAT-TRANSFER; REYNOLDS; EQUATIONS; PREDICTION; REGION; MODEL; SPEED; STATE;
D O I
10.1063/5.0221364
中图分类号
O3 [力学];
学科分类号
08 ; 0801 ;
摘要
This work aims to investigate the impact of the molecule-complexity effect and the non-ideal effect on wall-bounded turbulent flows by applying direct numerical simulation (DNS) to fully-developed channel flows of two typical organic vapors: R1233zd(E) and octamethyltrisiloxane (MDM). For each vapor, three thermodynamic states are analyzed: one in the dilute-gas region, one near the saturation line, and one in the supercritical region. For mean flow fields, it is found that, due to smaller Prandtl and Eckert numbers, both the molecule-complexity effect and the non-ideal effect reduce the mean temperature rise from the cold wall to the channel center. Meanwhile, the molecule-complexity effect weakens the mean density drop, while the non-ideal effect strengthens the drop. Furthermore, once the density and viscosity variations are considered, the mean streamwise velocity profiles of dense vapors are practically the same as the ideal gas. For turbulent fluctuations, it is found that the correlations between T ', p ', and rho ' in dense vapors are more complicated than the ideal gas: for the ideal gas, fluctuations are dominated by "vorticity mode"; hence, rho ' and T ' are strongly related to u ' but independent of p '; however, for dense vapors, "acoustic mode" can also play an important role. A newly derived equation illustrates that, through the "acoustic mode," the molecule-complexity effect obviously enhances the positive correlation between rho ' and p ', while the non-ideal effect can enhance the positive correlation between T ' and p '. Further analysis of instantaneous flow fields shows that p ' is isotropic. The isotropic character affects fluctuation magnitudes but has limited effect on the specified wall-direction turbulent transport. Consequently, Walz's equation and Reynolds analogy in terms of enthalpy are still valid. Finally, a comparison between the DNS energy budget and k equation of Reynolds-averaged Navier-Stokes (RANS) model has been carried out. Results show that obvious deviation happens on the production term in spite of the careful selection of eddy viscosity model.
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页数:22
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