Measurements of Reflected Shock Tunnel Freestream Nitric Oxide Temperatures and Partial Pressure

Girard, Julian J.; Finch, Peter M.; Strand, Christopher L.; Hanson, Ronald K.; Yu, Wesley M.; Austin, Joanna; Hornung, H. G.

doi:10.2514/1.j060596

Cited by 28 publications

(5 citation statements)

References 40 publications

(42 reference statements)

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“…Even if such measurements exist, it would almost certainly be associated with an uncertainty that is too large (around ±5-20 % as exemplified in Ref. [73,74]) to allow for any convincing observation of pumping which, as shown in the current work, is small. Therefore, no experimental works are available for any meaningful comparison.…”

Section: Nozzle Simulationsmentioning

confidence: 79%

Can vibrational pumping occur via O2–N2 collisions in nonequilibrium vibrationally excited air?

2023

Physics of Fluids

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The occurrence of vibrational pumping in air under nonequilibrium conditions is investigated as this phenomenon is not considered in the design of the current phenomenological models. It is shown that pumping can only happen during de-excitation and when the translational temperature is below around 1000 K. O2 is the molecule that would get pumped, and pumping will not occur when the initial equilibrium temperature is greater than around 1200–1600 K due to the formation of enough O to extinguish pumping via the O2–O vibration–translation reaction. The limiting initial temperature can be increased to around 2000 K if a nonequilibrium initial condition is considered. In cases where pumping does occur, constant–volume reactor simulations showed pumping of ≈5%. Nozzle simulations representative of that in hypersonic wind tunnels are conducted for an equilibrium temperature of 1100 K at the throat; pumping of up to around 10 K (≈1%) can be observed. It can be suggested that constant–volume reactors generally overestimate the manifestation of thermochemical nonequilibrium-associated phenomena and are a better zero-dimensional analogy for the relaxation process in flows with large length scales and no further expansion after an initial rapid expansion. After examination of the uncertainties of the most important rates used in the simulations, one may suggest that the current results correspond to the upper bound for the magnitude of pumping. It may be concluded that pumping is unimportant for practical intents and purposes in nonequilibrium hypersonic flows, and phenomenological models need not be able to recreate this phenomenon.

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Section: Nozzle Simulationsmentioning

confidence: 79%

Can vibrational pumping occur via O2–N2 collisions in nonequilibrium vibrationally excited air?

2023

Physics of Fluids

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“…Absorbance is related to the relevant thermal and physical properties of the absorbing medium through the Lambert-Beer Law (Girard et al, 2021) as follows:…”

Section: Data Analysis Methodsmentioning

confidence: 99%

Development of combustion gas measurement systems for micro-rocket torch using a diode laser sensor

HIRAYAMA,

OGAWA

2023

Mechanical Engineering Letters

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Much noise from the combustion oscillations and more are included in the measurement data for combustion experiments of micro-rocket torch. To develop the combustion gas measurement system for the micro-rocket torch using tunable diode laser absorption spectroscopy (TDLAS) method, we develop the denoising algorithms using the Savitzky-Golay filter and K-fold cross validation for improved noise-rejection capabilities. First, a validation study has been conducted on the gas measurement system using denoising algorithms in the case of atmospheric measurements. The atmospheric measurement results using denoising algorithms are in exceptionally good agreement with atmospheric conditions. Therefore, this result indicated that this algorithm gave satisfactory accuracies in the case of atmospheric measurements. Next, we investigated the combustion gas measurements for micro-rocket torch using the TDLAS method and demonstrated the usefulness of the denoising algorithms. From the results of this study, it is obvious that a significant accuracy improvement was obtained in the majority of absorbance spectrum cases with use of the denoising algorithms. Furthermore, the tendency of time-series torch gas temperature using TDLAS method is similar to the time-series estimated values.

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“…In this work, laser absorption spectroscopy (LAS) is utilized to measure the R(58) line of the ( ) fundamental band and the R(103), R(104), and R(140) lines of the ( ) fundamental band of CO via spectrally-resolved light attenuation in the mid-wave infrared. Although LAS theory is well-detailed in literature [ 21 ] and has been utilized to probe rovibrational non-equilibrium of NO and CO in other studies [ 19 , 22 ], key governing equations are described here for context and nomenclature definition. The Beer-Lambert law, given in Eq.…”

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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Measurements of Reflected Shock Tunnel Freestream Nitric Oxide Temperatures and Partial Pressure

Cited by 28 publications

References 40 publications

Can vibrational pumping occur via O2–N2 collisions in nonequilibrium vibrationally excited air?

Can vibrational pumping occur via O2–N2 collisions in nonequilibrium vibrationally excited air?

Development of combustion gas measurement systems for micro-rocket torch using a diode laser sensor

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

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