Nonequilibrium Spectral Radiation Behind the Shock Waves in Martian and Earth Atmospheres

“…The dissociation reactions, Reaction 6 and 7, are modeled using the rates of Park [11] considering the molecular species to be N 2 , and the atomic species to be O. Reaction 8, the reverse Zel'dovich process, is modeled using the rate of Dikalyuk [16]. To compare with previous simulations, Figs.…”

Section: Casementioning

confidence: 99%

Prediction of Flight Measurements of High-Enthalpy Nonequilibrium Flow from a CubeSat-Class Atmospheric Probe

Morgan

Nuwal

Williams

et al. 2018

2018 AIAA Aerospace Sciences Meeting

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“…The main radiators in these conditions are C 2 Swan bands, the CN red system, the CN violet system, and especially the CO fourth positive system, which is predicted to be the dominant source of shocklayer radiation during future Mars entries [5]. The dissociation of CO 2 is one of the most important reactions because it directly affects the rates of all chemical reactions, it affects the radiative flux generated by species, and the dissociation products (CO, O) considerably affect the heat flux on the heat shield via catalytic recombination reactions [6][7][8]. Although the chemical kinetics in the shock layer has been extensively studied, the mechanism of CO 2 dissociation under conditions relevant to Mars entry is not well understood.…”

Section: Introductionmentioning

confidence: 99%

“…The physical and chemical processes in a shock layer are usually studied in a shock tube or a shock tunnel, the conditions of which are the closest possible to the real conditions of entry into the planetary atmosphere. Different groups from the United States, Russia, Australia, Japan, and Europe have performed a number of shock-tube radiation experiments for Mars entry employing optical emission spectroscopy (OES) [8][9][10][11][12][13]. OES is a well-known nonintrusive diagnostic technique that has been widely used for studying chemical reactions and measuring absolute radiation.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Study of Carbon-Dioxide Dissociation for Mars Atmospheric Entry

Lin

Chen

et al. 2018

Journal of Thermophysics and Heat Transfer

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The mechanism of CO 2 dissociation during entry in the Mars atmosphere is experimentally investigated. A hydrogen-oxygen combustion-driven shock tube is used to simulate physical and chemical conditions in a CO 2-N 2 mixture. Two shock velocity/initial pressure conditions are studied: 7.09 0.05 km∕s at 100 Pa (called the low-pressure condition) and 5.68 0.07 km∕s at 300 Pa (called the high-pressure condition). The temperature behind the shock wave is obtained by analyzing the high-temporal-resolution and high-spatial-resolution experimental spectra of the CN violet (B 2 Σ → X 2 Σ , Δv 0) system. The CO number density is derived using a tunable diode laser absorption spectroscopy system based on CO absorption near 2.33 μm. Moreover, a numerical code is developed to reproduce the experimental results (temperatures and species densities). The kinetic code in this work is based on Park's two-temperature model. Comparisons between experiments and calculations are presented. Such a relatively simple two-temperature model fails to accurately describe the nonequilibrium temperature and CO number density but is suitable for equilibrium temperature predictions.

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“…Different groups from USA, Europe, Australia, Japan, and Russia performed a number of experiments on the physical and chemical processes behind a reentry shock wave in Martian-like mixtures, especially about non-equilibrium radiation and chemical reactions [8][9][10][11][12][13] . Up to now studies, the radiation measurements have been widely studied through optical emission spectroscopy (OES), and several chemical kinetic models have been established.…”

Section: Introductionmentioning

confidence: 99%

A new flux splitting scheme for Euler equations of gas dynamics

Li¹,

Hu²,

Jiang³

2015

AIP Conference Proceedings

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Shock tube experiments are carried out to study the physical and chemical processes during a vehicle entry into the Mars atmosphere using optical emission spectroscopy (OES) and tunable diode laser absorption spectroscopy (TDLAS). Gas temperature and CO concentration distribution are diagnosed behind a shock wave in a CO 2 -N 2 mixture with two different conditions of initial pressure and velocity. The strong shock wave is established in a shock tube driven by combustion of hydrogen and oxygen. Time-resolved spectra of the Δv = 0 sequence of the B 2 Σ + →X 2 Σ + electronic transition of CN have been observed through OES. A precise analysis of the CN violet spectra is performed and used to determine rotational and vibrational temperatures. Two absorption lines in the first overtone band of CO near 2.33 μm, are selected from a HITRAN simulation to calibrate laser wavelength and detect the CO concentration. Combined with these temperature results using OES, CO concentrations in the thermal equilibrium region are derived, which are 2.91 × 10 12 cm -3 and 1.01 × 10 13 cm -3 , corresponding to equilibrium temperatures equal to 7000 ± 400 K and 6000 ± 300 K in low and high pressure conditions, respectively.

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Nonequilibrium Spectral Radiation Behind the Shock Waves in Martian and Earth Atmospheres

Cited by 24 publications

References 29 publications

Prediction of Flight Measurements of High-Enthalpy Nonequilibrium Flow from a CubeSat-Class Atmospheric Probe

Prediction of Flight Measurements of High-Enthalpy Nonequilibrium Flow from a CubeSat-Class Atmospheric Probe

Experimental and Numerical Study of Carbon-Dioxide Dissociation for Mars Atmospheric Entry

A new flux splitting scheme for Euler equations of gas dynamics

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