Detailed Simulations of Shock-Bifurcation and Ignition of an Argon-diluted Hydrogen/Oxygen Mixture in a Shock Tube

Ihme, Matthias; Sun, Yong; Deiterding, Ralf

doi:10.2514/6.2013-538

Cited by 14 publications

(5 citation statements)

References 44 publications

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“…These shock tube investigations identified complex physical and chemical dynamics that influence mild ignition phenomena, where sensitivities to inhomogeneities in the mixture, impurities, wall properties, and the generation of local hot spots were highlighted. More recent experimental works have extended these insights [308][309][310][311], and detailed simulation techniques have been used where the development and evolution of non-uniformities caused by gas dynamic processes, especially boundary layer interactions with the reflected shock wave and shock bifurcation, have been studied [86,[312][313][314].…”

Section: Shock Tube Observationsmentioning

confidence: 99%

Advances in rapid compression machine studies of low- and intermediate-temperature autoignition phenomena

Goldsborough

Hochgreb

Vanhove

et al. 2017

Progress in Energy and Combustion Science

196

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Rapid compression machines (RCMs) are widely-used to acquire experimental insights into fuel autoignition and pollutant formation chemistry, especially at conditions relevant to current and future combustion technologies. RCM studies emphasize important experimental regimes, characterized by lowto intermediate-temperatures (600-1200 K) and moderate to high pressures (5-80 bar). At these conditions, which are directly relevant to modern combustion schemes including low temperature combustion (LTC) for internal combustion engines and dry low emissions (DLE) for gas turbine engines, combustion chemistry exhibits complex and experimentally challenging behaviors such as the chemistry attributed to cool flame behavior and the negative temperature coefficient regime. Challenges for studying this regime include that experimental observations can be more sensitive to coupled physicalchemical processes leading to phenomena such as mixed deflagrative/autoignitive combustion. Experimental strategies which leverage the strengths of RCMs have been developed in recent years to make RCMs particularly well suited for elucidating LTC and DLE chemistry, as well as convolved physicalchemical processes. Specifically, this work presents a review of experimental and computational efforts applying RCMs to study autoignition phenomena, and the insights gained through these efforts. A brief history of RCM development is presented towards the steady improvement in design, characterization, instrumentation and data analysis. Novel experimental approaches and measurement techniques, coordinated with computational methods are described which have expanded the utility of RCMs beyond empirical studies of explosion limits to increasingly detailed understanding of autoignition chemistry and the role of physical-chemical interactions. Fundamental insight into the autoignition chemistry of specific fuels is described, demonstrating the extent of knowledge of low-temperature chemistry derived from RCM studies, from simple hydrocarbons to multi-component blends and full-boiling range fuels. Emerging needs and further opportunities are suggested, including investigations of under-explored fuels and the implementation of increasingly higher fidelity diagnostics.

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Section: Shock Tube Observationsmentioning

confidence: 99%

Advances in rapid compression machine studies of low- and intermediate-temperature autoignition phenomena

Goldsborough

Hochgreb

Vanhove

et al. 2017

Progress in Energy and Combustion Science

196

View full text Add to dashboard Cite

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“…Ever since bifurcation was first observed by Mark in 1958, much work has been conducted to investigate bifurcation from experimental and numerical perspectives. ,− Of some of the insights gained from these works, a couple to note are the change in bifurcation length with changing mixture composition and the presence of nonuniform conditions after passage of the bifurcated reflected shock wave. The work of Lamnaouer et al provided insight into the nature of the nonuniform conditions, showing temperature and pressure gradients behind reflected shock waves when bifurcations were present.…”

Section: Experimental Nonidealitiesmentioning

confidence: 99%

Methane Ignition in a Shock Tube with High Levels of CO₂ Dilution: Consideration of the Reflected-Shock Bifurcation

Hargis

Petersen

2015

Energy Fuels

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Experiments were performed in a shock-tube facility to examine experimentally the kinetic effect, if any, of excess amounts of CO 2 as part of natural-gas-based fuel−oxidizer mixtures. An important aspect of these experiments was to also observe the role excess amounts of CO 2 play in causing nonidealities, particularly shock bifurcation, in shock-tube experiments using real (nondilute) fuel−air mixtures. Mixtures were composed of methane fuel at an equivalence ratio of 0.5 to represent a typical natural gas in a modified "air" mixture designed to study the effect of large levels of CO 2 dilution. These oxidizer compositions maintained constant levels of O 2 while exchanging N 2 for CO 2 in stages to give oxidizer mixture concentrations ranging from (0.21O 2 + 0.79N 2 ) to (0.21O 2 + 0.79CO 2 ). Low-pressure and high-pressure (near 1 and 10 atm, respectively) experiments were conducted over an approximate temperature range of 1450 to 1900 K. Results showed that the observed effect of CO 2 relating to reflected-shock bifurcation was quite significant, giving stronger bifurcation as amounts of CO 2 increased, as determined by a sidewall pressure transducer. Despite the presence of significant reflected-shock bifurcation in the mixtures containing high levels of CO 2 , the resulting ignition delay times were commensurate with the results expected if one were to assume the test conditions were at the inferred temperature and pressure immediately behind the reflected shock wave. That is, the main ignition events occurred in the gas closest to the endwall, where the effects of the shock bifurcation were minimal for the ignition delay time range of the present study. When the ignition delay times for mixtures with and without CO 2 dilution were compared, the effect of the CO 2 was minimal and within the uncertainty of the data, particularly for the experiments near 1 atm. A small effect of CO 2 addition was seen for the higher pressure near 10 atm, with a general increase in ignition delay time for the largest levels of CO 2 dilution. Predictions from a modern chemical kinetics model also showed a minimal effect of CO 2 addition on the methane ignition delay times, in agreement with the shock-tube data.

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“…One criterion by Meyer and Oppenheim (1971) states that the change of ignition-delay time with respect to the change of temperature ( ig ∕ T) p must be below a critical value (e.g., ig ∕ T = −2μs /K for stoichiometric hydrogen/oxygen mixtures) such that mild ignition occurs. Many numerical studies were published studying the mild ignition phenomenon in shock tube-simulations in 2D (Ihme et al 2013;Grogan and Ihme 2015;Oran and Gamezo 2007) and 3D (Khokhlov et al 2015). The studies focussed on the impact of the incident shock Mach number (Oran and Gamezo 2007), the evolution of ignition kernels due to velocity fluctuations (Ihme et al 2013), the effect of wall treatment on mild ignition (Grogan and Ihme 2015), and the development of hot spots in 3D (Khokhlov et al 2015).…”

Section: Remote Ignitionmentioning

confidence: 99%

“…Many numerical studies were published studying the mild ignition phenomenon in shock tube-simulations in 2D (Ihme et al 2013;Grogan and Ihme 2015;Oran and Gamezo 2007) and 3D (Khokhlov et al 2015). The studies focussed on the impact of the incident shock Mach number (Oran and Gamezo 2007), the evolution of ignition kernels due to velocity fluctuations (Ihme et al 2013), the effect of wall treatment on mild ignition (Grogan and Ihme 2015), and the development of hot spots in 3D (Khokhlov et al 2015). However, all these studies featured cases with bifurcated reflected shocks, while remote ignition was also observed in the absence of bifurcated reflected shocks (Hanson et al 2013).…”

Section: Remote Ignitionmentioning

confidence: 99%

Numerical Investigation of Remote Ignition in Shock Tubes

Lipkowicz

Nativel

Cooper

et al. 2020

Flow Turbulence Combust

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Highly resolved two- and three-dimensional computational fluid dynamics (CFD) simulations are presented for shock-tube experiments containing hydrogen/oxygen (H2/O2) mixtures, to investigate mechanisms leading to remote ignition. The results of the reactive cases are compared against experimental results from Meyer and Oppenheim (Proc Combust Inst 13(1): 1153–1164, 1971. 10.1016/s0082-0784(71)80112-1) and Hanson et al. (Combust Flame 160(9): 1550–1558, 2013. 10.1016/j.combustflame.2013.03.026). The results of the non-reactive case are compared against shock tube experiments, recently carried out in Duisburg and Texas. The computational domain covers the end-wall region of the shock tube and applies high order numerics featuring an all-speed approximate Riemann scheme, combined with a 5th order interpolation scheme. Direct chemistry is employed using detailed reaction mechanisms with 11 species and up to 40 reactions, on a grid with up to 2.2 billion cells. Additional two-dimensional simulations are performed for non-reactive conditions to validate the treatment of boundary-layer effects at the inlet of the computational domain. The computational domain covers a region at the end part of the shock tube. The ignition process is analyzed by fields of localized, expected ignition times. Instantaneous fields of temperature, pressure, entropy, and dissipation rate are presented to explain the flow dynamics, specifically in the case of a bifurcated reflected shock. In all cases regions with locally increased temperatures were observed, reducing the local ignition-delay time in areas away from the end wall significantly, thus compensating for the late compression by the reflected shock and therefore leading for first ignition at a remote location, i.e., away from the end wall where the ignition would occur under ideal conditions. In cases without a bifurcated reflected shock, the temperature increase results from shock attenuation. In cases with a bifurcated reflected shock, the formation of a second normal shock and shear near the slip line is found to be crucial for the remote ignition to take place. Overall, the two- and three-dimensional simulations were found to qualitatively explain the occurrence of remote ignition and to be quantitatively correct, implying that they include the correct physics.

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Detailed Simulations of Shock-Bifurcation and Ignition of an Argon-diluted Hydrogen/Oxygen Mixture in a Shock Tube

Cited by 14 publications

References 44 publications

Advances in rapid compression machine studies of low- and intermediate-temperature autoignition phenomena

Advances in rapid compression machine studies of low- and intermediate-temperature autoignition phenomena

Methane Ignition in a Shock Tube with High Levels of CO₂ Dilution: Consideration of the Reflected-Shock Bifurcation

Numerical Investigation of Remote Ignition in Shock Tubes

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Detailed Simulations of Shock-Bifurcation and Ignition of an Argon-diluted Hydrogen/Oxygen Mixture in a Shock Tube

Cited by 14 publications

References 44 publications

Advances in rapid compression machine studies of low- and intermediate-temperature autoignition phenomena

Advances in rapid compression machine studies of low- and intermediate-temperature autoignition phenomena

Methane Ignition in a Shock Tube with High Levels of CO2 Dilution: Consideration of the Reflected-Shock Bifurcation

Numerical Investigation of Remote Ignition in Shock Tubes

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Product

Resources

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Methane Ignition in a Shock Tube with High Levels of CO₂ Dilution: Consideration of the Reflected-Shock Bifurcation