Simulation of Supersonic Reacting Hydrocarbon Flows with Detailed Chemistry

A comparative analysis of the efficiency of approaches based on the exposure of reacting gas to resonance laser radiation to enhance combustion in a supersonic flow of H2–air mixture is conducted. The kinetic processes responsible for the intensification of chain reactions in premixed and non-premixed H2–air flows upon photodissociation of O2 molecules by 193.3 nm laser radiation, excitation of these molecules to the singlet sigma state by laser photons with 762.346 nm wavelength and heating the mixture by laser radiation are analysed in a detailed manner. It is shown that both photochemical methods, photodissociation and excitation of O2 molecules, are much more effective in shortening the ignition delay length than merely heating the mixture. For the premixed flow, the photodissociation of O2 molecules ensures a slightly higher reduction in the ignition delay than the laser-induced excitation of molecular oxygen to the singlet sigma state. However, in the non-premixed flow the situation is inverted. The analysis shows that both photochemical methods make it possible to raise the efficiency of conversion of reactant chemical energy to thermal energy released during combustion compared with the method of heating the mixtures.

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Accurate Spatial Resolution Estimates for Reactive Supersonic Flow with Detailed Chemistry

Powers

Paolucci

2005

AIAA Journal

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A robust method is developed and used to provide rational estimates of reaction zone thicknesses in onedimensional steady gas-phase detonations in mixtures of inviscid ideal reacting gases whose chemistry is described by detailed kinetics of the interactions of N molecular species constituted from L atomic elements. The conservation principles are cast as a set of algebraic relations giving pressure, temperature, density, velocity, and L species mass fractions as functions of the remaining N-L species mass fractions. These are used to recast the N-L species evolution equations as a self-contained system of nonlinear ordinary differential equations of the form dY i /dx = f i (Y 1 ,. .. , Y N-L). These equations are numerically integrated from a shock to an equilibrium end state. The eigenvalues of the Jacobian of f i are calculated at every point in space, and their reciprocals give local estimates of all length scales. Application of the method to the standard problem of a stoichiometric Chapman-Jouguet hydrogen-air detonation in a mixture with ambient pressure of 1 atm and temperature of 298 K reveals that the finest length scale is on the order of 10 −5 cm; this is orders of magnitude smaller than both the induction zone length, 10 −2 cm, and the overall reaction zone length, 10 0 cm. To achieve numerical stability and convergence of the solution at a rate consistent with the order of accuracy of the numerical method as the spatial grid is refined, it is shown that one must employ a grid with a finer spatial discretization than the smallest physical length scale. It is shown that published results of detonation structures predicted by models with detailed kinetics are typically underresolved by one to five orders of magnitude.

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Simulation of Supersonic Reacting Hydrocarbon Flows with Detailed Chemistry

Cited by 5 publications

References 15 publications

Kinetic analysis of n-decane–hydrogen blend combustion in premixed and non-premixed supersonic flows

Kinetic analysis of n-decane–hydrogen blend combustion in premixed and non-premixed supersonic flows

Numerical study of combustion initiation in a supersonic flow of H₂–air mixture by resonance laser radiation

Accurate Spatial Resolution Estimates for Reactive Supersonic Flow with Detailed Chemistry

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Simulation of Supersonic Reacting Hydrocarbon Flows with Detailed Chemistry

Cited by 5 publications

References 15 publications

Kinetic analysis of n-decane–hydrogen blend combustion in premixed and non-premixed supersonic flows

Kinetic analysis of n-decane–hydrogen blend combustion in premixed and non-premixed supersonic flows

Numerical study of combustion initiation in a supersonic flow of H2–air mixture by resonance laser radiation

Accurate Spatial Resolution Estimates for Reactive Supersonic Flow with Detailed Chemistry

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Product

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Numerical study of combustion initiation in a supersonic flow of H₂–air mixture by resonance laser radiation