NUMERICAL STUDY OF TURBULENT MIXING LAYERS WITH NON-EQUILIBRIUM IONIZATION CALCULATIONS

Turbulent mixing and autoignition of H2-rich fuels at relevant reheat combustor operating conditions are investigated in the present numerical study. The flow configuration under consideration is a fuel jet perpendicularly injected into a crossflow of hot flue gas (T > 1000K, p = 15bar). Based on the results of the experimental study for the same flow configuration and operating conditions two different fuel blends are chosen for the numerical simulations. The first fuel blend is a H2/natural gas/N2 mixture at which no autoignition events were observed in the experiments. The second fuel blend is a H2/N2 mixture at which autoignition in the mixing section occurred. First, the non-reacting flow simulations are performed for the H2/natural gas/N2 mixture in order to compare the accuracy of different turbulence modeling methods. Here the steady-state Reynolds-averaged Navier-Stokes (RANS) as well as the unsteady scale-adaptive simulation (SAS) turbulence modeling methods are applied. The velocity fields obtained in both simulations are directly validated against experimental data. The SAS method shows better agreement with the experimental results. In the second part of the present work the autoignition of the H2/N2 mixture is numerically studied using the 9-species 21-steps reaction mechanism of O’Conaire et al. [1]. As in the reference experiments, autoignition can be observed in the simulations. Influences of the turbulence modeling as well as of the hot flue gas temperature are investigated. The onset and the propagation of the ignition kernels are studied based on the SAS modeling results. The obtained numerical results are discussed and compared with data from experimental autoignition studies.

Download Full-text

Numerical study of the exchange term in the non-equilibrium water flow model for double-porosity soils

Poromechanics III - Biot Centennial (1905-2005) ◽

10.1201/noe0415380416.ch56 ◽

2005 ◽

Cited By ~ 1

Author(s):

J Lewandowska ◽

A Szymkiewicz ◽

M Vauclin

Keyword(s):

Water Flow ◽

Flow Model ◽

Numerical Study ◽

Double Porosity ◽

Exchange Term ◽

Non Equilibrium

Download Full-text

Numerical Study of Non-Equilibrium Plasma Assisted Combustion on Spacecraft Rocket Engine

Proceedings of the Advances in Materials, Machinery, Electrical Engineering (AMMEE 2017) ◽

10.2991/ammee-17.2017.117 ◽

2017 ◽

Author(s):

Zheng Zhang ◽

Xueke Che ◽

Jinlong Li ◽

Wansheng Nie ◽

Zhi Zheng ◽

...

Keyword(s):

Numerical Study ◽

Rocket Engine ◽

Plasma Assisted Combustion ◽

Equilibrium Plasma ◽

Non Equilibrium

Download Full-text

Statistical characteristics of turbulent mixing in spherical and cylindrical converging Richtmyer–Meshkov instabilities

Journal of Fluid Mechanics ◽

10.1017/jfm.2021.818 ◽

2021 ◽

Vol 928 ◽

Author(s):

Xinliang Li ◽

Yaowei Fu ◽

Changping Yu ◽

Li Li

Keyword(s):

Turbulent Mixing ◽

Initial Perturbation ◽

Great Influence ◽

Mixing Layers ◽

Statistical Characteristics ◽

Computational Domain ◽

Heavy Fluid ◽

Node Number ◽

Geometric Effect ◽

Atwood Number

In this paper, the Richtmyer–Meshkov instabilities in spherical and cylindrical converging geometries with a Mach number of approximately 1.5 are investigated by using the high resolution implicit large eddy simulation method, and the influence of the geometric effect on the turbulent mixing is investigated. The heavy fluid is sulphur hexafluoride (SF6), and the light fluid is nitrogen (N2). The shock wave converges from the heavy fluid into the light fluid. The Atwood number is 0.678. The total structured and uniform Cartesian grid node number in the main computational domain is 20483. In addition, to avoid the influence of boundary reflection, a sufficiently long sponge layer with 50 non-uniform coarse grids is added for each non-periodic boundary. Present numerical simulations have high and nonlinear initial perturbation levels, which rapidly lead to turbulent mixing in the mixing layers. Firstly, some physical-variable mean profiles, including mass fraction, Taylor Reynolds number, turbulent kinetic energy, enstrophy and helicity, are provided. Second, the mixing characteristics in the spherical and cylindrical turbulent mixing layers are investigated, such as molecular mixing fraction, efficiency Atwood number, turbulent mass-flux velocity and density self-correlation. Then, Reynolds stress and anisotropy are also investigated. Finally, the radial velocity, velocity divergence and enstrophy in the spherical and cylindrical turbulent mixing layers are studied using the method of conditional statistical analysis. Present numerical results show that the geometric effect has a great influence on the converging Richtmyer–Meshkov instability mixing layers.

Download Full-text