Uncertainty and Sensitivity Analysis of Thermochemical Modeling for Titan Atmospheric Entry

Bose, Deepak; Wright, Michael J.; Gökçen, Tahir

doi:10.2514/6.2004-2455

Cited by 61 publications

(48 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previously, Bose et al [38] conducted a Monte Carlo analysis to determine the sensitivity and influence of the Gök&en Titan reaction set [9]. The analysis was performed to identify the propagation of the major sources of uncertainty in the thermochemical model [38]. The three reactions identified were N 2 H $ N N H, N 2 H $ NH H, and N 2 C $ CN N. The reaction N 2 C $ CN N was identified to effect the radiation to a lesser extent than N 2 H $ N N H and N 2 H $ NH H. However, by analyzing the reaction set one parameter at a time, important coupling effects between reactions can be overlooked, namely, the coupling between N 2 M $ N N M and N 2 C $ CN N. Furthermore, the Monte Carlo analysis can fail to provide data regarding the absolute impact of how one reaction interacts with the uncertainty impact of another reaction.…”

Section: Influence Of Important Cn Radiation Reactionsmentioning

confidence: 97%

See 1 more Smart Citation

Analysis of Nonequilibrium CN Radiation Encountered During Titan Atmospheric Entry

Brandis

Morgan

McIntyre

2011

Journal of Thermophysics and Heat Transfer

View full text Add to dashboard Cite

The focus of this paper is to analyze the Titan reaction scheme and determine the mechanisms that control the formation and decay of the radiation emitted by the cyanogen molecule (CN) during entry into Titan's atmosphere. Through a parametric study of important reactions combined with an investigation into reaction pathways, it has been concluded that the coupling between the dissociation of N 2 and the formation of the CN (through the reaction N 2 C $ CN N) controls the radiation decay rate. The reason for the super equilibrium concentrations (approximately 50% higher than equilibrium) was identified to be a result of the N 2 C $ CN N reaction continuing to overproduce the CN after nominal equilibrium values were reached. This is due to the slow buildup of N to drive the reverse reaction. The absolute level of emitted radiation has been shown to be controlled by the lifetime of the CNB state and the excitation of CNX to CNB by heavy particle impact. Thus, it is the conclusion of this paper that CN radiation is primarily controlled by N 2 dissociation.

show abstract

Section: Influence Of Important Cn Radiation Reactionsmentioning

confidence: 97%

Section: Influence Of Important Cn Radiation Reactionsmentioning

confidence: 99%

Analysis of Nonequilibrium CN Radiation Encountered During Titan Atmospheric Entry

Brandis

Morgan

McIntyre

2011

Journal of Thermophysics and Heat Transfer

View full text Add to dashboard Cite

show abstract

“…A study by Wright et al [29] indicates that there can be as much as 30% uncertainty associated with binary collision integrals. Published work by Bose and Wright [12], Palmer [30], and Bose et al [31] have treated binary collision integrals as uncertain. The catalytic wall recombination efficiency is another source of uncertainty that strongly affects the convective heat transfer.…”

Section: Description Of the Stochastic Problemmentioning

confidence: 98%

Uncertainty Analysis of Mars Entry Flows over a Hypersonic Inflatable Aerodynamic Decelerator

Brune

West

Hosder

et al. 2015

Journal of Spacecraft and Rockets

View full text Add to dashboard Cite

A detailed uncertainty analysis for high-fidelity flowfield simulations over a fixed aeroshell of hypersonic inflatable aerodynamic decelerator scale for Mars entry is presented for fully laminar and turbulent flows at peak stagnationpoint heating conditions. This study implements a sparse-collocation approach based on stochastic expansions for efficient and accurate uncertainty quantification under a large number of uncertainty sources in the computational model. The convective and radiative heating and shear stress uncertainties are computed over the hypersonic inflatable aerodynamic decelerator surface and are shown to vary due to a small fraction of 65 flowfield and radiation modeling parameters considered in the uncertainty analysis. The main contributors to the convective heating uncertainty near the stagnation point are the CO 2 -CO 2 , CO 2 -O, and CO-O binary collision interactions, freestream density, and freestream velocity for both boundary-layer flows. In laminar flow, exothermic recombination reactions are more important at the shoulder. The main contributors to radiative heating at the nose and flank were the CO 2 dissociation rate and CO heavy-particle excitation rates, whereas the freestream density showed importance toward the shoulder. The CO 2 -CO 2 interaction and freestream velocity and density control the wall shear stress uncertainty. Nomenclature D = statistical variance N s = number of samples N t = number of terms in a total-order polynomial chaos expansion N TP = number of test points n = number of random dimensions p = order of polynomial expansion S e = percent absolute error S T = total Sobol index T e = test point error α = deterministic coefficient in polynomial chaos expansion α = generic uncertain function δ = truncation error μ e = mean error ξ = standard input random variable Ψ = random basis function Ω 1;1 = diffusion collision integral Ω 2;2 = viscosity collision integral

show abstract

“…The chemical model is the one of Park et al [9] for a mixture of eleven species. Following the suggestion of [10], the random variable for the chemical reactions is the preexponential factor A r of the Arrhenius rate equation: k r = A r T b exp(−C r /T ). Indeed, other parameters such as the activation energy are known with higher accuracy.…”

Section: Introductionmentioning

confidence: 99%

Uncertainty quantification for characterization of high enthalpy facilities

Villedieu

Cappaert

Galache

et al. 2013

Progress in Flight Physics

View full text Add to dashboard Cite

The post §ight analysis of a space mission requires accurate determination of the free-stream conditions for the trajectory. The Mach number, temperature, and pressure conditions can be rebuilt from the heat §ux and pressure measured on the spacecraft by means of a Flush Air Data System (FADS). This instrumentation comprises a set of sensors §ush mounted in the thermal protection system to measure the static pressure (pressure taps) and heat §ux (calorimeters). Knowing that experimental data su¨er from errors, this methodology needs to integrate quanti¦cation of uncertainties. Epistemic uncertainties on the models for chemistry in the bulk and at the wall (surface catalysis) should also be taken into account. To study this problem it is necessary to solve a stochastic backward problem. This paper focuses on a preliminary sensitivity analysis of the forward problem to understand which uncertainties need to be accounted for. In section 2, the uncertainty quanti¦cation methodologies used in this work are presented. Section 3 is dedicated to the one-dimensional (1D) simulations of the shock layer to identify which chemical reactions of the mechanism need to be accounted for in the Uncertainty Quanti¦cation (UQ). After this triage procedure, the two-dimensional (2D) axisymmetric §ow around the blunt nose was simulated for two trajectory points of EXPERT (EXPErimental Reentry Test-bed) is simulated and the propagation of the uncertainties on the stagnation pressure and heat §ux has been studied.

show abstract

Uncertainty and Sensitivity Analysis of Thermochemical Modeling for Titan Atmospheric Entry

Cited by 61 publications

References 21 publications

Analysis of Nonequilibrium CN Radiation Encountered During Titan Atmospheric Entry

Analysis of Nonequilibrium CN Radiation Encountered During Titan Atmospheric Entry

Uncertainty Analysis of Mars Entry Flows over a Hypersonic Inflatable Aerodynamic Decelerator

Uncertainty quantification for characterization of high enthalpy facilities

Contact Info

Product

Resources

About