Shock-Tube Boundary-Layer Effects on Reflected-Shock Conditions with and Without CO2

Hargis, Joshua W.; Petersen, Eric L.

doi:10.2514/1.j055253

Cited by 30 publications

(13 citation statements)

References 15 publications

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“…50 Previous investigations have highlighted the importance of reporting nonidealities present in unmodified shock tubes as they can significantly affect pressure and temper-ature conditions, which in turn significantly affect ignition and kinetics measurements. [51][52][53][54] Chief among these is the change in pressure with time, dP*/dt (where dP* denotes the change in pressure normalized to the test pressure P 5 , ie, dP/P 5 ), of which less than 2%/ms was seen for all experiments, and this change in pressure is negligible in the short domain where the reaction rate is measured for this study (<50 μs). It should also be noted that a slightly different behavior is observed at these test conditions (∼1.4 atm) in terms of dP*/dt, and for the first 100 μs the pressure is relatively unchanged due to a relatively long laminar boundary layer, making these conditions particularly ideal for these experiments.…”

Section: Shock Tubementioning

confidence: 99%

Isopropanol dehydration reaction rate kinetics measurement using H₂O time histories

Cooper

Mulvihill

Mathieu

et al. 2020

Int J of Chemical Kinetics

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H 2 O formation during thermal decomposition of isopropanol was measured behind reflected shock waves at temperatures ranging from 1127 to 1621 K at an average pressure of 1.42 atm using a laser absorption technique. Of the five modern chemical kinetics models used to compare the H 2 O time histories, the model from Li et al (Combust. Flame 2019;207:171-185) showed the best overall agreement. Sensitivity and rate of production analyses using the Li et al model (as well as those from AramcoMech 3.0, CRECK, and Togbe et al (Energy Fuel. 2011;25:676-683)) showed unimolecular dehydration of isopropanol, iC 3 H 7 OH ⇌ H 2 O + C 3 H 6 (R1), is nearly the sole reaction controlling H 2 O production at early times, allowing for an a priori measurement of the forward rate constant k 1. The Arrhenius expression k 1 (s-1) = 2.60 × 10 13 exp(−31 120 K/T) was determined to represent best the data from this study. According to the models and previous experimental investigations, the pressure investigated is well within the high-pressure limit (HPL) for this reaction. Additional, higher-pressure experiments also confirmed the HPL assumption. An uncertainty analysis was performed by varying secondary reactions within their uncertainties and examining their effect on the overall prediction, establishing an uncertainty within ±20% for all but the highest temperature cases, which have a maximum uncertainty of ±40%. Experiments conducted with a radical trapper, toluene, showed little influence from radical chemistry, suggesting this estimated uncertainty is fairly conservative. Experimental data from Heyne et al (Z Phys Chem. 2015;229:881-907) were found to be in good agreement with the rate measurements from this study and, therefore, a second Arrhenius expression, k 1 (s-1) = 2.11 × 10 13 exp(−30 820 K/T), was found to represent both datasets well. This second expression has a larger temperature range of 976-1621 K. The present study provides the first high-temperature data collected for this reaction, adding to the limited data available for isopropanol in the literature.

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Section: Shock Tubementioning

confidence: 99%

Isopropanol dehydration reaction rate kinetics measurement using H₂O time histories

Cooper

Mulvihill

Mathieu

et al. 2020

Int J of Chemical Kinetics

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“…For the 50% CO2 diluted mixtures, dP5/dt was found to be between 2.4 -32.5%/ms, and for the 50% N2 mixtures 11.2 -49.2%/ms, resulting in over 16 K and 34 K temperature increases, respectively. Again, the interpretation of this is clouded with the coupled effects; nevertheless, we could determine dP5/dt was not directly correlated with temperature and mixtures with N2 had larger dP5/dt, similarly discussed in Hargis and Petersen [45]. Further investigation for 50% dilution at these conditions should be properly carried out with use of nonreactive mixtures, whereby the associated effects of bifurcation on pressure and temperature rise can be characterized.…”

Section: Resultsmentioning

confidence: 66%

“…From this pressure rise, a temperature rise can be modeled assuming an isentropic process [44]. The pressure rise as discussed previously [45], can be an order of magnitude higher in mixtures with CO2 when compared to mixtures of Ar.…”

Section: Resultsmentioning

confidence: 99%

Effects of High Fuel Loading and CO2 Dilution on Oxy-Methane Ignition Inside a Shock Tube at High Pressure

Laich

Baker

Ninnemann

et al. 2020

Journal of Energy Resources Technology

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Ignition delay times were measured for methane/O2 mixtures in a high dilution environment of either CO2 or N2 using a shock tube facility. Experiments were performed between 1044 K and 1356 K at pressures near 16 ± 2 atm. Test mixtures had an equivalence ratio of 1.0 with 16.67% CH4, 33.33% O2, and 50% diluent. Ignition delay times were measured using OH* emission and pressure time-histories. Data were compared to the predictions of two literature kinetic mechanisms (ARAMCO MECH 2.0 and GRI Mech 3.0). Most experiments showed inhomogeneous (mild) ignition which was deduced from five time-of-arrival pressure transducers placed along the driven section of the shock tube. Further analysis included determination of blast wave velocities and locations away from the end wall of initial detonations. Blast velocities were 60–80% of CJ-Detonation calculations. A narrow high temperature region within the range was identified as showing homogenous (strong) ignition which showed generally good agreement with model predictions. Model comparisons with mild ignition cases should not be used to further refine kinetic mechanisms, though at these conditions, insight was gained into various ignition behavior. To the best of our knowledge, we present first shock tube data during ignition of high fuel loading CH4/O2 mixtures diluted with CO2 and N2.

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“…Non-ideal effects resulting in attenuation of the incident shock wave of shock tubes are of significant interest in particular for chemical kinetic studies [44,45]. These non-ideal effects mainly depend on the boundary layer, experimental conditions, and the shock tube geometry, particularly the inner diameter of the tube [46][47][48]. To estimate the shock attenuation for the divider, the recently determined empirical relations given in [47] are used.…”

Section: Divider Flow Evolutionmentioning

confidence: 99%

Numerical and experimental evaluation of shock dividers

et al. 2022

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Mitigation of pressure pulsations in the exhaust of a pulse detonation combustor is crucial for operation with a downstream turbine. For this purpose, a device termed the shock divider is designed and investigated. The intention of the divider is to split the leading shock wave into two weaker waves that propagate along separated ducts with different cross sections, allowing the shock waves to travel with different velocities along different paths. The separated shock waves redistribute the energy of the incident shock wave. The shock dynamics inside the divider are investigated using numerical simulations. A second-order dimensional split finite volume MUSCL-scheme is used to solve the compressible Euler equations. Furthermore, low-cost simulations are performed using geometrical shock dynamics to predict the shock wave propagation inside the divider. The numerical simulations are compared to high-speed schlieren images and time-resolved total pressure recording. For the latter, a high-frequency pressure probe is placed at the divider outlet, which is shown to resolve the transient total pressure during the shock passage. Moreover, the separation of the shock waves is investigated and found to grow as the divider duct width ratio increases. The numerical and experimental results allow for a better understanding of the dynamic evolution of the flow inside the divider and inform its capability to reduce the pressure pulsations at the exhaust of the pulse detonation combustor.

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Shock-Tube Boundary-Layer Effects on Reflected-Shock Conditions with and Without CO2

Cited by 30 publications

References 15 publications

Isopropanol dehydration reaction rate kinetics measurement using H₂O time histories

Isopropanol dehydration reaction rate kinetics measurement using H₂O time histories

Effects of High Fuel Loading and CO2 Dilution on Oxy-Methane Ignition Inside a Shock Tube at High Pressure

Numerical and experimental evaluation of shock dividers

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Shock-Tube Boundary-Layer Effects on Reflected-Shock Conditions with and Without CO2

Cited by 30 publications

References 15 publications

Isopropanol dehydration reaction rate kinetics measurement using H2O time histories

Isopropanol dehydration reaction rate kinetics measurement using H2O time histories

Effects of High Fuel Loading and CO2 Dilution on Oxy-Methane Ignition Inside a Shock Tube at High Pressure

Numerical and experimental evaluation of shock dividers

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Isopropanol dehydration reaction rate kinetics measurement using H₂O time histories

Isopropanol dehydration reaction rate kinetics measurement using H₂O time histories