Dependence of Calculated Postshock Thermodynamic Variables on Vibrational Equilibrium and Input Uncertainty

Campbell, Matthew F.; Owen, Kyle G.; Davidson, David F.; Hanson, Ronald K.

doi:10.2514/1.t4952

Cited by 62 publications

(19 citation statements)

References 125 publications

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“…Incident shock wave velocities ranged from 1.1 -2.9 km/s generating equilibrium temperatures from 1250 -3460 K and equilibrium pressures from 0.03 -0.17 atm. From the normal shock relations solver [19], the measured temperatures after relaxation and equilibrium temperatures can be compared to validate the sensor and method. The deviation of the measured temperatures with the simulated shock temperature from theory [19], is shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

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High-speed interband cascade laser absorption sensor for multiple temperatures in CO2 rovibrational non-equilibrium

Jelloian

Minesi

Spearrin

2022

AIAA SCITECH 2022 Forum

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An RF-diplexed laser absorption technique is employed to resolve spectral transitions of CO 2 in the mid-infrared at MHz rates to infer non-equilibrium temperatures of rotation and vibration. A distributed feedback interband cascade laser (DFB-ICL) resolves 7 transitions within the CO 2 fundamental asymmetric stretch band near 4.19 µm, representing a range of rotational and vibrational energies. Non-equilibrium spectra are resolved at MHz rates and fit with a two-temperature model for line intensities. The sensor is demonstrated on a high enthalpy shock tube, targeting temperatures between 1250 -3500 K and sub-atmospheric pressures in various CO 2 -Ar gas mixtures. Tests have shown that this sensor provides sensitive temperature measurements with 1-µs resolution over a wide range of conditions relevant to Mars entry radiation. Vibrational relaxation times on the order of 10 µs are resolved and compared to existing models.

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Section: Resultsmentioning

confidence: 99%

“…From the normal shock relations solver [19], the measured temperatures after relaxation and equilibrium temperatures can be compared to validate the sensor and method. The deviation of the measured temperatures with the simulated shock temperature from theory [19], is shown in Fig. 4.…”

Section: Resultsmentioning

confidence: 99%

High-speed interband cascade laser absorption sensor for multiple temperatures in CO2 rovibrational non-equilibrium

Jelloian

Minesi

Spearrin

2022

AIAA SCITECH 2022 Forum

View full text Add to dashboard Cite

show abstract

“…This is expected because translational and rotational energy modes equilibrate significantly faster than the vibrational energy mode [ 14 , 34 ]. The energy modes are also seen to equilibrate to the temperature predicted from the normal shock relations solver [ 28 ], indicating an accurate and quantitative temperature measurement.…”

Section: Results/sensor Demonstrationmentioning

confidence: 99%

“…Figure 5 illustrates the solution method. The density profile behind the incident shock is modeled by an exponential increase from the vibrationally frozen density predicted from the normal shock relations solver [ 28 ] to the equilibrium number density after relaxation. Figure 4 shows the absorbance area of the R(103) feature is most sensitive to over the temperature range of 1500–3000 K. While any line area may be theoretically used to infer a value, the R(103) and R(104) lines are preferentially used here as R(58) can be optically thick, and R(140) is often optically thin.…”

Section: Methods and Theorymentioning

confidence: 99%

High-speed mid-infrared laser absorption spectroscopy of CO$$_2$$ for shock-induced thermal non-equilibrium studies of planetary entry

2022

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A high-speed laser absorption technique is employed to resolve spectral transitions of CO$$_2$$ 2 in the mid-infrared at MHz rates to infer non-equilibrium populations/temperatures of translation, rotation and vibration in shock-heated CO$$_2$$ 2 - Ar mixtures. An interband cascade laser (DFB-ICL) resolves 4 transitions within the CO$$_2$$ 2 asymmetric stretch fundamental bands ($$\Delta $$ Δ v$$_3$$ 3 = 1) near 4.19 $$\upmu \hbox {m}$$ μ m . The sensor probes a wide range of rotational energies as well as two vibrational states (00$$^0$$ 0 0 and 01$$^1$$ 1 0). The sensor is demonstrated on the UCLA high enthalpy shock tube, targeting temperatures between 1250 and 3100 K and sub-atmospheric pressures (up to 0.2 atm). The sensor is sensitive to multiple temperatures over a wide range of conditions relevant to Mars entry radiation. Vibrational relaxation times are resolved and compared to existing models of thermal non-equilibrium. Select conditions highlight the shortcomings of modeling CO$$_2$$ 2 non-equilibrium with a single vibrational temperature.

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“…For all experiments, reflected shock pressure in the shock tube test section is measured directly with a dynamic pressure transducer (Kistler 601B1) via a charge amplifier (Kistler 5018A) and temperature is inferred from the shock wave speed determined via time of arrival sensors (Dynasen, Inc.) along the shock tube. Uncertainties in reflected shock test conditions are typically about 1% when properly accounting for vibrational relaxation of all components of the test gas [30].…”

Section: B Experimental and Optical Setupmentioning

confidence: 99%

Kinetics of methyl methacrylate (MMA) combustion assessed by time-resolved speciation behind shock waves

Kuenning

Sanders

Mellor

et al. 2022

AIAA SCITECH 2022 Forum

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Dependence of Calculated Postshock Thermodynamic Variables on Vibrational Equilibrium and Input Uncertainty

Cited by 62 publications

References 125 publications

High-speed interband cascade laser absorption sensor for multiple temperatures in CO2 rovibrational non-equilibrium

High-speed interband cascade laser absorption sensor for multiple temperatures in CO2 rovibrational non-equilibrium

High-speed mid-infrared laser absorption spectroscopy of CO$$_2$$ for shock-induced thermal non-equilibrium studies of planetary entry

Kinetics of methyl methacrylate (MMA) combustion assessed by time-resolved speciation behind shock waves

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