Pulsating instability in near-limit propagation of rich hydrogen/air flames

Christiansen, Erik W.; Sung, Chih-Jen; Law, Chung K.

doi:10.1016/s0082-0784(98)80446-3

Cited by 39 publications

(10 citation statements)

References 8 publications

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“…At first glance, these oscillations resemble the well-known thermo-diffusive flame instability often observed in homogeneous gas [19] and quasi-homogeneous solid mixtures [20], and also recently observed in aluminum dust flames [21]. The physical mechanisms underlying the thermo-diffusive instability and the heterogeneous pulsating flame shown here are, however, fundamentally different.…”

Section: Kinetic-diffusive Instabilitiessupporting

confidence: 80%

Thermal structure and burning velocity of flames in non-volatile fuel suspensions

Soo

Kumashiro

Goroshin

et al. 2017

Proceedings of the Combustion Institute

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Flame propagation through a non-volatile solid-fuel suspension is studied using a simplified, time-dependent numerical model that considers the influence of both diffusional and kinetic rates on the particle combustion process. It is assumed that particles react via a single-step, first-order Arrhenius surface reaction with an oxidizer delivered to the particle surface through gas diffusion. Unlike the majority of models previously developed for flames in suspensions, no external parameters are imposed, such as particle ignition temperature, combustion time, or the assumption of either kinetic-or diffusion-limited particle combustion regimes. Instead, it is demonstrated that these parameters are characteristic values of the flame propagation problem that must be solved together with the burning velocity, and that the a priori imposition of these parameters from single-particle combustion data may result in erroneous predictions. It is also shown that both diffusive and kinetic reaction regimes can alternate within the same flame and that their interaction may result in non-trivial flame behavior. In fuel-lean mixtures, it is demonstrated that this interaction leads to certain particle size ranges where burning velocity increases with increasing particle size, opposite to the expected trend. For even leaner mixtures, the interplay between kinetic and diffusive reaction rates leads to the appearance of a new type of flame instability where kinetic and diffusive regimes alternate in time, resulting in a pulsating regime of flame propagation.

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Section: Kinetic-diffusive Instabilitiessupporting

confidence: 80%

Thermal structure and burning velocity of flames in non-volatile fuel suspensions

Soo

Kumashiro

Goroshin

et al. 2017

Proceedings of the Combustion Institute

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show abstract

“…Calculations also show that the rich limit of the H 2 /O 2 flame increases with decreasing pressure. We further note that for near rich limit hydrogen flames, in which the Lewis number is greater than unity, pulsating instability has been observed to take place in mixtures with fuel concentrations slightly below that of the rich limit [11][12][13] and the flame is found to oscillatorily extinguish well ahead of the static extinction limit [12,13]. Therefore, the flammability range of a H 2 /O 2 mixture is expected to be narrowed when the intrinsic oscillatory nature of flame propagation is taken into account.…”

Section: Flame Characteristics and Quenching Diametermentioning

confidence: 64%

Catalyzed Combustion of Bipropellants for Micro-Spacecraft Propulsion

Schneider

Sung

Boyarko

2003

39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit

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“…Calculations at 34.5 kPa show that the rich limit of the H 2 /O 2 flame occurs at an equivalence ratio of 12.78, which corresponds to a mixture ratio of 0.626 and a hydrogen mole fraction of 0.962. We further note that for near rich limit hydrogen flames, in which the Lewis number is greater than unity, pulsating instability has been observed to take place in mixtures with fuel concentrations slightly below that of the rich limit [7,10,11] and the flame is found to oscillatorily extinguish well ahead of the static extinction limit [10,11]. Therefore, the flammability range of a H 2 /O 2 mixture is expected to be narrowed when the intrinsic oscillatory nature of flame propagation is taken into account.…”

Section: Flame Characteristics and Quenching Diametermentioning

confidence: 99%