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

作者：Yu Rixin; Lipatnikov Andrei N

来源：Physics of Fluids, 2017, 29(6): 065116.

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'/SL <= 90 of the r. m. s. turbulent velocity to the laminar wave speed and a ratio of 0.39 <= L-11/delta(F) <= 12.5 of the longitudinal integral length scale of the turbulence to the laminar wave thickness. Accordingly, the Damkohler Da = (L11SL)/(u' delta(F)) and Karlovitz Ka = delta(F)/(SL tau(eta)) numbers were varied from 0.01 to 24.7 and from 0.36 to 587, respectively. Here, tau(eta) 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 root Da. 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/delta(F). Moreover, scaling laws U-T proportional to u'(alpha) S-L(1-alpha) (L-11/delta(F))(beta) are substantially different for developing U-T(t) and fully developed U-T(s), i.e., the scaling exponents alpha and, especially, beta depend on the wave-development time. Furthermore, alpha and, especially, beta 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, delta(F)}, obtained by parameterizing various experimental databases. Published by AIP Publishing.

• 出版日期2017-6