On autoignition-dominated supersonic combustion

Cymbalist, Niccolo; Dimotakis, Paul E.

doi:10.2514/6.2015-2315

Cited by 6 publications

(9 citation statements)

References 48 publications

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“…The evolution-variable manifold approach of Cymbalist and Dimotakis [25,26] has been implemented in a parallel implicit unstructured grid CFD code and compared with an experimental test case of reacting hydrogen in a supersonic crossflow. The EVM approach precomputes and tabulates the chemical composition and rate of change of the evolution variable as a function of the computed density, energy, mixture fraction, and evolution variable.…”

Section: Discussionmentioning

confidence: 99%

“…For the hydrogen-air system, this phase of the reaction is reliably predicted by detailed chemical kinetics and requires no special handling. However, when the induction period is poorly predicted by detailed chemical kinetics, the EVM methodology offers an alternative data-driven approach incorporating a characteristic ignition-delay time, and it has been applied to ethylene [25,26]. A similar approach was used by Li et al [29] to represent the induction process in the simulation of detonations.…”

Section: Evolution-variable Manifold Approachmentioning

confidence: 99%

“…Additional details may be found in the work of Cymbalist and Dimotakis [25,26]. In the EVM framework, the state of a reacting gas is represented in terms of four flowfield variables.…”

Section: Evolution-variable Manifold Approachmentioning

confidence: 99%

“…Recently, Cymbalist and Dimotakis [25,26] proposed an approach to model high-speed combustion flows, including the effects of ignition delay and combustion in the DRZ regime. Their evolutionvariable manifold (EVM) approach explicitly represents ignition delay and subsequent heat release as separate phases of combustion.…”

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confidence: 99%

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Wall-Modeled Large-Eddy Simulation of Autoignition-Dominated Supersonic Combustion

2017

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Simulations of combustion in high-speed and supersonic flows need to account for autoignition phenomena, compressibility, and the effects of intense turbulence. In the present work, the evolution-variable manifold framework of Cymbalist and Dimotakis ("On Autoignition-Dominated Supersonic Combustion," AIAA Paper 2015-2315, June 2015) is implemented in a computational fluid dynamics method, and Reynolds-averaged Navier-Stokes and wall-modeled large-eddy simulations are performed for a hydrogen-air combustion test case. As implemented here, the evolution-variable manifold approach solves a scalar conservation equation for a reaction-evolution variable that represents both the induction and subsequent oxidation phases of combustion. The detailed thermochemical state of the reacting fluid is tabulated as a low-dimensional manifold as a function of density, energy, mixture fraction, and the evolution variable. A numerical flux function consistent with local thermodynamic processes is developed, and the approach for coupling the computational fluid dynamics to the evolution-variable manifold table is discussed. Wall-modeled large-eddy simulations incorporating the evolution-variable manifold framework are found to be in good agreement with full chemical kinetics model simulations and the jet in supersonic crossflow hydrogen-air experiments of Gamba and Mungal ("Ignition, Flame Structure and Near-Wall Burning in Transverse Hydrogen Jets in Supersonic Crossflow," Journal of Fluid Mechanics, Vol. 780, Oct. 2015, pp. 226-273). In particular, the evolutionvariable manifold approach captures both thin reaction fronts and distributed reaction-zone combustion that dominate high-speed turbulent combustion flows.Nomenclature a = speed of sound, m∕s C; X ; Z = progress variable, nonfuel mass fraction, and fuel mass fraction c v ; c v;s = mixture and s-species specific heats, J∕kg ⋅ K D = diffusion coefficient, m 2 ∕s E = total energy per unit volume, J∕m 3 e; e s = mixture and s-species specific energy, J∕kg F = convective flux vector h; h 0 = enthalpy and total enthalpy, J∕kg i = grid index J = jet momentum ratio j h = diffusive enthalpy flux k = kinetic energy, J∕kg L; R = values obtained from left and right data M s = s-species molar mass, kg∕kmol N s = number of species in detailed kinetics model n; n x ; n y ; n z = element face unit normal vector and components p = pressure, Pa q j = heat flux vector= vectors of conserved and primitive variables u; u; v; w = velocity vector and components, m∕s u 0 = face-normal velocity component, m∕s x; x j = position vector and its components, m Y s = s-species mass fraction α = dissipative flux factor δ R = reaction-zone thickness, m ε = dissipation rate ζ = evolution-variable source term, 1∕s η k = Kolmogorov length scale, m Λ; λ = diagonal matrix of eigenvalues and eigenvalue ν t ; ν = turbulence field variable and kinematic viscosity ρ; ρ s = density and s-species density, kg∕m 3 σ ij = viscous and Reynolds stress τ = evolution variable ϕ = stoichiometric fuel-air ratio χ = subgrid-s...

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Section: Discussionmentioning

confidence: 99%

Section: Evolution-variable Manifold Approachmentioning

confidence: 99%

“…Additional details may be found in the work of Cymbalist and Dimotakis [25,26]. In the EVM framework, the state of a reacting gas is represented in terms of four flowfield variables.…”

Section: Evolution-variable Manifold Approachmentioning

confidence: 99%

mentioning

confidence: 99%

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Wall-Modeled Large-Eddy Simulation of Autoignition-Dominated Supersonic Combustion

2017

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“…In the present paper, we have extended the EVM approach to high-speed turbulent combustion of ethylene. In previous work, 1 Cymbalist and Dimotakis developed a complete description of ethylene ignition and oxidation based on the available experimental data and a chemical-kinetics mechanism for ethylene-air combustion. This model has been tabulated in a form suitable for use in the US3D-EVM CFD code.…”

Section: Introductionmentioning

confidence: 99%

Application of the Evolution-Variable Manifold Approach to Cavity-Stabilized Ethylene Combustion

Cymbalist

Candler

Dimotakis

2016

46th AIAA Fluid Dynamics Conference

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For combustion in high-speed flows, radical-formation time scales and ignition delay times may be similar to, or dominate, relevant flow time scales. Reliable modeling of induction and autoignition processes is critical to the prediction of combustor performance. The evolution-variable manifold (EVM) approach of Cymbalist and Dimotakis 1 uses a transported scalar to track the evolution of the reaction processes, from induction leading to autoignition and subsequent robust combustion. In the present work, the EVM method is implemented in a computational fluid dynamics code in which wall-modeled large-eddy simulations are performed for two ethylene-air high-speed combustion cases. The detailed thermochemical state of the reacting fluid is tabulated as a function of a reduced number of state variables that include density, energy, mixture fraction, and the reaction-evolution variable. A thermodynamically consistent numerical flux function is developed and the approach for coupling the large-eddy simulation to the EVM framework is discussed. It is found that particular attention must be given to the solution of the energy equation to obtain accurate and computationally stable results. The results show that the LES-EVM approach shows promise for the simulation of turbulent combustion of hydrocarbons in high-speed flows, including those dominated by ignition delay, and encompass regions of thin reaction fronts as well as distributed reaction zones.

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Large-Eddy Simulation of Autoignition-Dominated Supersonic Combustion

Candler

Subbareddy

Cymbalist

et al. 2015

45th AIAA Fluid Dynamics Conference

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The simulation of low-speed combustion flows is well established. However, at highspeed conditions where radical formation and ignition delay are important, there is much less experience with turbulent combustion modeling. In the present work, a novel evolution variable manifold (EVM) approach of Cymbalist and Dimotakis 1,2 is implemented in a production CFD code and preliminary RANS and large-eddy simulations are computed for a hydrogen combustion test case. The EVM approach solves a scalar conservation equation for the induction time to represent ignition delay. The state of the combustion products is tabulated as a function of density, energy, mixture fraction, and the evolution variable. A thermodynamically-consistent numerical flux function is developed and the approach for coupling the EVM table to CFD is discussed. Initial simulations show that the EVM approach produces good agreement with full chemical kinetics model simulations. Work remains to be done to improve the numerical stability, extend the grid, and increase the order of accuracy of the simulations.

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On autoignition-dominated supersonic combustion

Cited by 6 publications

References 48 publications

Wall-Modeled Large-Eddy Simulation of Autoignition-Dominated Supersonic Combustion

Wall-Modeled Large-Eddy Simulation of Autoignition-Dominated Supersonic Combustion

Application of the Evolution-Variable Manifold Approach to Cavity-Stabilized Ethylene Combustion

Large-Eddy Simulation of Autoignition-Dominated Supersonic Combustion

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