DNS study of dependence of bulk consumption velocity in a constant-density reacting flow on turbulence and mixture characteristics

• Published in: Physics of fluids (1994) 2017-06, Vol.29 (6), p.15
• Main Authors: Yu, Rixin, Lipatnikov, Andrei N.
• Format: Article
• Language: English
• Subjects: Bulk density; Computational fluid dynamics; Computer simulation; Dependence; Direct numerical simulation; Engineering and Technology; Fluid dynamics; Fluid Mechanics and Acoustics; Maskinteknik; Mechanical Engineering; Physics; Reacting flow; Scaling laws; Strömningsmekanik och akustik; Teknik; Turbulence; Turbulent flow; Wave propagation
• ISSN: 1070-6631; 1089-7666; 1089-7666
• DOI: 10.1063/1.4990836

3D Direct Numerical Simulation (DNS) study of propagation of a single-reaction wave in forced, statistically stationary, homogeneous, isotropic, and constant-density turbulence was performed in order to evaluate both developing U T t and fully developed U T s bulk turbulent consumption velocities by independently varying a ratio of 0.5 ≤ u ′ ∕ S L ≤ 90 of the r.m.s. turbulent velocity to the laminar wave speed and a ratio of 0.39 ≤ L 11 ∕ δ F ≤ 12.5 of the longitudinal integral length scale of the turbulence to the laminar wave thickness. Accordingly, the Damköhler D a = ( L 11 S L ) ∕ ( u ′ δ F ) and Karlovitz K a = δ F ∕ ( S L τ η ) numbers were varied from 0.01 to 24.7 and from 0.36 to 587, respectively. Here, τ η is the Kolmogorov time scale. The obtained DNS data show that, at sufficiently low Da, the fully developed ratio of U T s ∕ u ′ is mainly controlled by Da and scales as D a . However, such a scaling should not be extrapolated to high Da. The higher Da (or the lower Ka), the less pronounced dependence of U T s ∕ u ′ on a ratio of L 11 ∕ δ F . Moreover, scaling laws U T ∝ u ′ α S L 1 − α ( L 11 ∕ δ F ) β are substantially different for developing U T t and fully developed U T s , i.e., the scaling exponents α and, especially, β depend on the wave-development time. Furthermore, α and, especially, β depend on a method used to evaluate the developing U T t . Such effects can contribute to significant scatter of expressions for U T or S T as a function of { u ′ , S L , L 11, δ F }, obtained by parameterizing various experimental databases.