Simulations of Carbon-Dioxide Equilibrium Infrared Radiation Measurements

Lemal, Adrien; Takayanagi, Hideaki; Nomura, Satoshi; Fujita, Kazuhisa

doi:10.2514/1.t5134

Cited by 6 publications

(3 citation statements)

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“…JAXA included CO 2 modeling in the SPRADIAN radiation code. So far only equilibrium results [16] have been published although work is underway to simulate nonequilibrium spectra [17]. The PASTIS [18] radiation code, developed to study the emission of a nonequilibrium CO 2 plasma, is limited to the CO 2 dissociation products and does not include CO 2 itself.…”

Section: Introductionmentioning

confidence: 99%

RADIS: A nonequilibrium line-by-line radiative code for CO2 and HITRAN-like database species

Pannier

Laux

2019

Journal of Quantitative Spectroscopy and Radiative Transfer

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Section: Introductionmentioning

confidence: 99%

RADIS: A nonequilibrium line-by-line radiative code for CO2 and HITRAN-like database species

Pannier

Laux

2019

Journal of Quantitative Spectroscopy and Radiative Transfer

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“…Good agreement was observed for both the radiating bands. Further validation of CDSD-4000 under equilibrium conditions was shown by Lemal et al [47]. Using the experimental measurements of Depraz et al as well as other experimental measurements of CO2 radiation under thermochemical equilibrium conditions, Palmer and Cruden [48] validated the implementation of the CDSD-4000 database in the NEQAIR radiation code [49] for simulating CO2 radiation.…”

Section: Carbon Dioxide Thermochemistry and Radiationmentioning

confidence: 95%

“…Although numerous work has already been done on validating the CDSD-4000 database for simulating CO2 radiation [45] [48] [47], the experimental data used for the validation were mainly from plasma torch facilities (or other similar facilities) creating subsonic flows in thermochemical equilibrium. The characteristics of the flow around the wedge in the current work is supersonic with mild non-equilibrium between the rotational and vibrational modes and, mainly, frozen chemistry (this is shown in section 6.6).…”

Section: 2mentioning

confidence: 99%

Mars entry afterbody radiative heating: an experimental study of nonequilibrium CO2 expanding flow

Gu¹

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This thesis presents an experimental study of high temperature CO2 flowsfocusing on CO2 flows subjected to rapidly expanding conditions relevant to Mars entry and representative of the corner expansion around the shoulder, between the windward and leeward flows, on an entry capsule. This is an important but poorly understood aspect of spacecraft design. Past numerical research showed that, during Mars entry, the CO2 4.3 µm and 2.7 µm band radiation from the aforementioned expanding flow produce non-negligible contributions to the heating of the capsule afterbody.Consequently, this radiative heating should be considered in the sizing of the afterbody thermal protection systems (TPS). However, due to a lack of experimental research, the nonequilibrium characteristics of CO2 expanding flows are not well understood. Therefore, to help with the design of future Mars entry vehicles, it is necessary to investigate such flows.The X2 expansion tube was used to facilitate the current study. Three expansion tube test conditions with differing velocitiesnominally 2.8 km/s, 3.4 km/s, and 4.0 km/swere developed. Using a two-dimensional wedge model with a 54° convex corner along with the new conditions, flows with similarities to the expanding flow around the shoulder of an aeroshell at certain Mars entry conditions were created. Mid-wavelength infrared emission spectroscopy of the 4.3 μm and 2.7 μm bands were performed on the flow. The spectroscopic measurements were used to estimate the rotational and vibrational temperatures and the CO2 number densities using a spectral fitting method. Supplementing the spectroscopic measurements, filtered images of the 4.3 μm and 2.7 μm bands were taken to provide a two-dimensional spatial map of the band radiance in the flow around the wedge. Estimates of the experimental inflow conditions were produced by solving for the intermediate test gas states using measurements of various properties of the operating condition. CO2 spectroscopic measurements of the inflow along with measurements of the wedge model shock location and deduced post-shock conditions were also used to help characterize the test conditions. Using estimated inflow conditions, three-dimensional CFD simulations of the experiments were conducted using a two-temperature model. The computed results were compared to the available measurements to examine the appropriateness of the current numerical model at simulating the CO2 flow.Important qualitative results were obtained in this thesis in regards to the high temperature CO2expanding flow. The temperatures estimated in the wedge flow using both the 2.7 and 4.3 µm spectroscopic measurements were found to be the same. This provides some confidence to the validity of NEQAIR, using CDSD-4000, at predicting CO2 radiation under gas-dynamic conditions which are more relevant to Mars entry. Using the estimated rotational and vibrational temperatures, the CO2 II thermal non-equilibrium in the expanding flow was shown to be smallless than 10%. As the experiments simulate the expanding fl...

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