Abstract
In this paper, 3D turbulent V-shaped flame channel configuration of H2 - air premix combustion is investigated for the examining transient entropy generation at atmospheric pressure. The analysis is based on computing the exact source terms of entropy transport equation using Direct Numerical Simulation (DNS) coupled with detailed chemistry (with N2 gas as inert) to capture key turbulence-chemistry interaction with all scales of turbulence
and flame. In the present study, it provides more useful insight than previously reported literature available on the entropy generation analysis of H2-air combustion on both laminar and turbulent premix flames with investigation of role of temperature and species mass fraction fluctuations in identifying fluctuation correlations with other quantities in modeling of transport and production terms of mean entropy in the RANS formulation.
Prior to multidimensional case, 1-D planar (laminar) premix flame is investigated to assess components of entropy generation and influence of non-linear product term of species gradient and species concentration in entropy generation due to mass transfer, is critical in turbulent premix flames and it is found to be negligible in laminar premix flames. The parametric study proposed to set lower bound of species consumption in turbulent premix flames (because of non-linear term of species-gradient and species concentration) to produce bounded entropy generation and ignoring radicals formation. The Entropy balance analysis reveal that 3D V-shaped flame reacting flow is expanding as the flame propagates in the downstream and chemical non-equilibrium state occurs in flame configuration. The increasing entropy generation is observed across the domain, largely contributed by
temperature gradient and chemical reactions as flame propagates. The hydrogen -air premix combustion analysis is based on Ret = 180 (based on the friction velocity) and equivalence ratio (j) of 1.5.
Keywords: Entropy generation, DNS (Direct Numerical Simulation), premixed H2-air combustion,V-shaped flame configuration,Entropy analysis, RANS(Reynolds Averaged Navier Stokes)
and flame. In the present study, it provides more useful insight than previously reported literature available on the entropy generation analysis of H2-air combustion on both laminar and turbulent premix flames with investigation of role of temperature and species mass fraction fluctuations in identifying fluctuation correlations with other quantities in modeling of transport and production terms of mean entropy in the RANS formulation.
Prior to multidimensional case, 1-D planar (laminar) premix flame is investigated to assess components of entropy generation and influence of non-linear product term of species gradient and species concentration in entropy generation due to mass transfer, is critical in turbulent premix flames and it is found to be negligible in laminar premix flames. The parametric study proposed to set lower bound of species consumption in turbulent premix flames (because of non-linear term of species-gradient and species concentration) to produce bounded entropy generation and ignoring radicals formation. The Entropy balance analysis reveal that 3D V-shaped flame reacting flow is expanding as the flame propagates in the downstream and chemical non-equilibrium state occurs in flame configuration. The increasing entropy generation is observed across the domain, largely contributed by
temperature gradient and chemical reactions as flame propagates. The hydrogen -air premix combustion analysis is based on Ret = 180 (based on the friction velocity) and equivalence ratio (j) of 1.5.
Keywords: Entropy generation, DNS (Direct Numerical Simulation), premixed H2-air combustion,V-shaped flame configuration,Entropy analysis, RANS(Reynolds Averaged Navier Stokes)