Sensitivity of intrinsic low-dimensional manifolds with respect to kinetic data

König, Karin; Maas, Ulrich

doi:10.1016/j.proci.2004.08.217

Cited by 14 publications

(5 citation statements)

References 11 publications

(11 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Using finite differences can yield problems with the (16), as the fast subspacesZ f might be obtained with an arbitrary scaling [42]. Thus, we suggest to use a scalinginvariant formulation as it was also applied in [43]. The scaling invariant equations read:…”

Section: Timescale Analysesmentioning

confidence: 99%

Investigation of the Dynamical Response of Methane/Air Counterflow Flames to Inflow Mixture Composition and Flow Field Perturbations

König

Bykov

Maas

2008

Flow Turbulence Combust

Self Cite

View full text Add to dashboard Cite

This work presents an analysis of the response of laminar, stretched, premixed CH 4 -air counterflow flames subject to periodical perturbations of the inflow mixture composition and the flow field in the context of ILDM and REDIM. Investigations of the perturbation propagation show, that the perturbation reaches the flame under certain conditions only; changes of the perturbation due to dissipative processes are investigated. Different methods are applied to gain an in-depth view of the influence of the perturbation on the chemical kinetics, namely correlation analyses of species in state space and timescale and element composition analyses. For the timescale analyses, two methods are applied, the ILDM method and a new concept for timescale analysis within the REDIM method. It is shown, that the perturbation does not change the global behaviour of the chemical kinetics and it is suggested to apply REDIMs for a low-dimensional description of perturbed flames.

show abstract

Section: Timescale Analysesmentioning

confidence: 99%

Investigation of the Dynamical Response of Methane/Air Counterflow Flames to Inflow Mixture Composition and Flow Field Perturbations

König

Bykov

Maas

2008

Flow Turbulence Combust

Self Cite

View full text Add to dashboard Cite

show abstract

“…Recent developments place further emphasis on global aspects [40][41][42][43][44] and extend sensitivity analysis to transport properties [45,46] and uncertainties [47][48][49][50].…”

Section: ''Embarrassment Of Success''mentioning

confidence: 99%

Transforming data into knowledge—Process Informatics for combustion chemistry

Frenklach

2007

Proceedings of the Combustion Institute

167

137

View full text Add to dashboard Cite

“…Generally, these are based on the separation of reactions according to their time constants and invoking steady-state methods. These are the so-called Intrinsic Low-Dimensional Manifold − or the Computational Singular Perturbation − approaches or other more recent emerging reduced model concepts. , In a few of the modeling attempts with acetylene, pictorial reaction networks outline the numerous reactions interconnecting the many species. ,, Of the two species of interest to the present study, only CH is considered. The models suggest that CH is either one step away from final oxidation or may with C 2 H 2 be a building block for c -C 3 H 2 .…”

Section: Previous Measurements Of Ch and C2 In Flamesmentioning

confidence: 99%

CH and C₂ Measurements Imply a Radical Pool within a Pool in Acetylene Flames

Schofield

Steinberg

2007

J. Phys. Chem. A

View full text Add to dashboard Cite

Measured CH and C2 profiles show a striking resemblance as a function of time in a series of seven well-characterized fuel-rich (phi=1.2-2.0) non-sooting acetylene flames. This implied commonality and interrelationship are unexpected as these radicals have dissimilar chemical kinetic natures. As a result, a rigorous examination was undertaken of the behavior of each of the hydrocarbon species known to be present, C, CH, CH2, CH3, CH4, CHO, CHOH, CH2O, CH2OH, CH3O, CH3OH, C2, C2H, C2H2, CHCO, CH2CO, and C2O. This emphasized the main region where CH and C2 are observed (50-600 micros) and reduced the kinetic reactions to only those that operate efficiently and are dominant. It was immediately apparent that this region of the flame reflects the nature of a hydrogen flame heavily doped with CO and CO2 and containing traces of hydrocarbons. The radical species, H, OH, O, along with H2, H2O, and O2, form an important controlling radical pool that is in partial equilibrium, and the concentrations of each of the hydrocarbon radicals are minor to this, playing secondary roles. As a result, the dominant fast reactions are those between the hydrocarbons and the basic hydrogen/oxygen radicals. Hydrocarbon-hydrocarbon reactions are unimportant here at these equivalence ratios. CH and C2 are formed and destroyed on a sub-microsecond time scale so that their flame profiles are the reflection of a complex kinetically dynamic system. This is found to be the case for all of the hydrocarbon species examined. As might be expected, these rapidly form steady-state distributions. However, with the exceptions of C, CHO, CHOH, and CH2O, which are irreversibly being oxidized, the others all form an interconnected hydrocarbon pool that is under the control of the larger hydrogen radical pool. The hydrocarbon pool can rapidly adjust, and the CH and C2 decay together as the pool is drained. This is either by continuing oxidation in less rich mixtures, or in richer flames where this is negligible by the onset of hydrocarbon-hydrocarbon reactions. The implications of such a hydrocarbon pool are significant. It introduces a buffering effect on their distribution and provides the indirect connection between CH and C2. Moreover, because they are members of this radical pool, flame studies alone cannot answer questions concerning their specific importance in combustion other than their contributing role to this pool. The presence of such a pool modifies the exactness that is needed for kinetic mechanisms, and knowledge of every species in the system no longer is necessary. Furthermore, as rate constants become refined, it will allow for the calculation of the relative concentrations of the hydrocarbon species and facilitate reduced kinetic mechanisms. It provides an explanation for previous isotopically labeled experiments and illustrates the difficulty of exactly identifying in flames the role of individual species. It resolves the fact that differing kinetic models can show similar levels of accuracy and has implications for sensitivity analyses...

show abstract

Sensitivity of intrinsic low-dimensional manifolds with respect to kinetic data

Cited by 14 publications

References 11 publications

Investigation of the Dynamical Response of Methane/Air Counterflow Flames to Inflow Mixture Composition and Flow Field Perturbations

Investigation of the Dynamical Response of Methane/Air Counterflow Flames to Inflow Mixture Composition and Flow Field Perturbations

Transforming data into knowledge—Process Informatics for combustion chemistry

CH and C₂ Measurements Imply a Radical Pool within a Pool in Acetylene Flames

Contact Info

Product

Resources

About

Sensitivity of intrinsic low-dimensional manifolds with respect to kinetic data

Cited by 14 publications

References 11 publications

Investigation of the Dynamical Response of Methane/Air Counterflow Flames to Inflow Mixture Composition and Flow Field Perturbations

Investigation of the Dynamical Response of Methane/Air Counterflow Flames to Inflow Mixture Composition and Flow Field Perturbations

Transforming data into knowledge—Process Informatics for combustion chemistry

CH and C2 Measurements Imply a Radical Pool within a Pool in Acetylene Flames

Contact Info

Product

Resources

About

CH and C₂ Measurements Imply a Radical Pool within a Pool in Acetylene Flames