Convective and Radiative Heat Flux Prediction of Huygens's Entry on Titan

Walpot, L.; Caillault, L.; Molina, Rafael Cuevas; Laux, Christophe O.; Blanquaert, T

doi:10.2514/1.20901

Cited by 13 publications

(13 citation statements)

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“…Here κ λ ϕ 0 is the absorption coefficient evaluated at some reference state ϕ 0 . This leads to dI k ds k ϕ; kfϕ; ϕ 0 ; kI ne b ϕ − I k (9) provided that at every wavelength across the entire spectrum, where κ λ ϕ 0 k, we also have a unique value for κ λ ϕ k ϕ; k everywhere within the medium. This is the statement of correlated absorption coefficient [29,30].…”

Section: Planck Function-weighted Full-spectrummentioning

confidence: 99%

“…Radiative heating from the CN molecule was predicted to be of critical importance in the design of the European Space Agency's Huygens probe. At peak heating the radiative heat flux was predicted to be as high as twice the convective heat flux [9,10]. For NASA's Titan Aerocapture mission, analyses have predicted that radiative heating from CN can be as high as 300 W∕cm 2 at the stagnation point [4,5,11], more than four times the convective fluxes.…”

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confidence: 99%

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Modeling of Radiative Heat Transfer in Carbonaceous Atmospheres Using k-Distribution Models

Bansal

Modest

2013

Journal of Thermophysics and Heat Transfer

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Full-spectrum correlated k-distribution models are presented for bands of CN and CO for applications relevant to entry into atmospheres of Titan, Mars, Venus and flows over an ablating heat shield. A new emission-weighted fullspectrum k-distribution model is proposed as an improvement over the more popular Planck function-weighted fullspectrum k-distribution model. In the new reordering scheme, emission coefficient is used as the weight instead of the Planck-function. To exploit the full potential of the k-distribution method databasing schemes for k distributions are discussed and CPU time studies are presented. The accuracy of the new model and the database is demonstrated by solving the radiative transfer equation for two-cell problems and stagnation line flowfields of Titan's Huygens spacecraft and a spacecraft entering into the Martian atmosphere.

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Section: Planck Function-weighted Full-spectrummentioning

confidence: 99%

mentioning

confidence: 99%

Modeling of Radiative Heat Transfer in Carbonaceous Atmospheres Using k-Distribution Models

Bansal

Modest

2013

Journal of Thermophysics and Heat Transfer

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“…This case is found to produce a peak radiative heat flux equal to about half the peak radiative heat flux of the nominal trajectory. The heat load, which corresponds to the integral of the heat flux over the entire trajectory, is slightly higher than for the nominal trajectory (35 MJ/m 2 as compared with 36.5 MJ/m 2 for the nominal trajectory [ Walpot et al , 2005, 2006]). Yelle min [95‐5‐0] −68 NoGW corresponds to the steepest entry trajectory, the upper limit of methane mole fraction (5%) and the lower limit of argon mole fraction (0%) of the Yelle model, and no gravity waves.…”

Section: Sensitivity Of the Radiative Heat Fluxes To The Flowfield Pamentioning

confidence: 99%

Radiative heating predictions for Huygens entry

Caillault¹,

Walpot²,

Magin³

et al. 2006

J. Geophys. Res.

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[1] Radiative heat flux predictions for the Huygens probe entry into Titan's atmosphere are presented in this paper. Radiative heating was computed with the radiation code SPECAIR, assuming a Boltzmann distribution of the excited electronic levels at a characteristic temperature taken as the vibrational temperature of the gas. CN violet is found to be the most intense emitter, followed by CN red, C 2 Swan, and at early trajectory points by the first and second positive systems of N 2 . Solutions of the 1-D radiative transport equation along stagnation streamlines show that self-absorption by the plasma layer reduces the total emission by up to about 20%. The fine structure of the CN violet spectra (spin-splitting) was taken into account to accurately determine self-absorption by CN violet. The potential importance of argon radiation was estimated and shown to be negligible. The resulting fluxes were found to be sustainable by the Huygens's Thermal Protection System. The feasibility of the mission was deemed possible under the updated entry parameters and atmospheric composition.

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“…The second step is the measurement of nonequilibrium spectra, producing data for the development of electronically and vibrationally resolved collisional-radiative models. As stated earlier, the nonequilibrium flow conditions in the immediate postshock region present during entry or aerocapture in the atmosphere of Titan, which have been computed for flight conditions [1][2][3][4][5][6][7][8][9] or simulated in shock tubes [14][15][16][17], cannot be replicated in the facility used for the present investigation. Moreover, the total specific enthalpy of the VKI Minitorch facility, which was in the range of 8-10 MJ=kg on the jet axis, is rather low with respect to the required values ranging from 12.5 to 15 MJ=kg for peak radiative heating of the Huygens entry [9].…”

Section: Introductionmentioning

confidence: 99%

“…E VEN if performed at moderate speed (6-10 km=s) [1][2][3][4][5][6][7], entry or aerocapture maneuvers in the atmosphere of Titan are characterized by significant radiation emission in the shock layer surrounding the space probe. This strong emission is due to the composition of the atmosphere of Titan, which is mainly composed of nitrogen with a small percentage of methane.…”

Section: Introductionmentioning

confidence: 99%