Measurement and Characterization of Mid-wave Infrared Radiation in CO2 Shocks

Cruden, Brett A.; Brandis, Aaron M.; Prabhu, Dinesh K.

doi:10.2514/6.2014-2962

Cited by 36 publications

(49 citation statements)

References 21 publications

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“…The simulations underpredict the 2600-3404 nm wavelength range by as much as a factor of 3, as was shown in our previous publication for similar conditions [10]. The underprediction may indicate that the CO 2 dissociation rate at the shock front is too fast with the Mitcheltree kinetics.…”

Section: Radiative Heating Predictionmentioning

confidence: 52%

“…Although in previous publications, we have postulated that the effect of shock deceleration may appear similar to an increased velocity [19,20], this effect is not expected to be noticeable within 2 cm of the shock front. The alternative would be to attribute the difference to the kinetic model, as we have explored in previous publications [10]. As shown in [10], different models match the data at different velocities, the result of which would be a shift when the data are compared with only one model as a function of velocity.…”

Section: Radiative Heating Predictionmentioning

confidence: 96%

“…The alternative would be to attribute the difference to the kinetic model, as we have explored in previous publications [10]. As shown in [10], different models match the data at different velocities, the result of which would be a shift when the data are compared with only one model as a function of velocity. Other works have explored adjustments to the chemical kinetics at higher velocity and shown significant impact on radiative heating in nonequilibrium [18,20,21].…”

Section: Radiative Heating Predictionmentioning

confidence: 96%

“…The Martian atmosphere was modeled as 97% CO 2 and 3% N 2 (by mass). The difference in composition to the actual Martian atmosphere has insignificant impact at these velocities where the radiation is dominated by CO 2 [10]. The TPS surface was treated as a nonporous, no-slip, radiative equilibrium wall with constant emissivity (ε 0.89) and the Mitcheltree-Gnoffo surface catalycity model was used [11].…”

Section: Computational Approachmentioning

confidence: 99%

“…Radiation from these shocks was measured from the vacuum ultraviolet (VUV) through MWIR using instrumentation described previously [8][9][10]. The instrumentation ranges are given in Table 2.…”

Section: Experimental Approachmentioning

confidence: 99%

See 4 more Smart Citations

Radiative Heating During Mars Science Laboratory Entry: Simulation, Ground Test, and Flight

Cruden

Brandis

White

et al. 2016

Journal of Thermophysics and Heat Transfer

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The heat shield of the Mars Science Laboratory was equipped with thermocouple stacks to measure in-depth heating of the thermal protection system during atmospheric entry. The heat load derived from the thermocouples in the stagnation region was found to be 33% lower than corresponding postflight predictions of convective heating alone. It was hypothesized that this difference could be attributed to radiation from the shock-heated gas, a mechanism not considered in preflight analyses of flowfields. To test the hypothesis and quantify the contribution of shock-layer radiation to total surface heating, ground tests and simulations (both flow and radiation) were performed at several points along the best-estimated entry trajectory of the Mars Science Laboratory. The present paper provides an assessment of the quality of the radiation model and its impact to stagnation point heating. The impact of radiative heating is shown to account for 43% of the heat load discrepancy. Additional possible factors behind the remaining discrepancy are discussed. Nomenclature B λ T = Planck (blackbody) function at temperature, T, W∕cm 2 · sr · μm D = shock-tube diameter, m d = shock standoff distance, m e λ x = emission coefficient at position x, W∕cm 2 · sr · μm L λ x = spectral radiance at position x, W∕cm 2 · sr · μm L λ x; θ = spectral radiance at position x at off-normal angle θ, W∕cm 2 · sr · μm _ m = mass blowing rate, kg∕m 2 · s q = heat flux or irradiance Tx = temperature at position x, K v = velocity, m∕s x = position along stagnation line or perpendicular to heat shield, cm or m y = position along heat shield surface, m δ = boundary-layer thickness, m θ = off-normal angle, rad λ = wavelength, nm p c = ablation product density, kg∕m 3

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Section: Radiative Heating Predictionmentioning

confidence: 52%

Section: Radiative Heating Predictionmentioning

confidence: 96%

Section: Radiative Heating Predictionmentioning

confidence: 96%

Section: Computational Approachmentioning

confidence: 99%

Section: Experimental Approachmentioning

confidence: 99%

See 3 more Smart Citations

Radiative Heating During Mars Science Laboratory Entry: Simulation, Ground Test, and Flight

Cruden

Brandis

White

et al. 2016

Journal of Thermophysics and Heat Transfer

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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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Development and commissioning of the T6 Stalker Tunnel

et al. 2021

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The T6 Stalker Tunnel is a multi-mode, high-enthalpy, transient ground test facility. It is the first of its type in the UK. The facility combines the original free-piston driver from the T3 Shock Tunnel with modified barrels from the Oxford Gun Tunnel. Depending on test requirements, it can operate as a shock tube, reflected shock tunnel or expansion tube. Commissioning tests of the free-piston driver are discussed, including the development of four baseline driver conditions using piston masses of either 36 kg or 89 kg. Experimental data are presented for each operating mode, with comparison made to numerical simulations. In general, high-quality test flows are observed. The calculated enthalpy range of the experimental conditions achieved varies from $$2.7\hbox { MJ kg}^{-1}$$ 2.7 MJ kg - 1 to $$115.0\hbox { MJ kg}^{-1}$$ 115.0 MJ kg - 1 . Graphical abstract

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Measurement and Characterization of Mid-wave Infrared Radiation in CO2 Shocks

Cited by 36 publications

References 21 publications

Radiative Heating During Mars Science Laboratory Entry: Simulation, Ground Test, and Flight

Radiative Heating During Mars Science Laboratory Entry: Simulation, Ground Test, and Flight

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

Development and commissioning of the T6 Stalker Tunnel

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