Blunt-Body Aerothermodynamic Database from High-Enthalpy Carbon-Dioxide Testing in an Expansion Tunnel

Hollis, Brian R.; Prabhu, Dinesh K.; MacLean, Matthew; Dufrene, Aaron

doi:10.2514/1.t5019

Cited by 35 publications

(18 citation statements)

References 21 publications

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“…These detailed analyses further reveal the mechanism of catalytic properties and provide a reference for more precise aeroheating predictions. However, due to the lack of reliable data, the adsorption characteristics of CO 2 and N 2 molecules into PICA (TPS material for the MSL heatshield [14]) in extreme conditions are not clearly known [32]. Thus, supercatalytic boundary condition, which produces the highest possible surface heating prediction and is conservative for the TPS design [32], has been commonly utilized for Mars atmospheric entry simulations for the sake of safety [9,14,28].…”

Section: Discretization and Boundary Conditionsmentioning

confidence: 99%

“…It is implemented to recombine the species mass fraction to the freestream's value, that is, 97% for CO 2 , 3% for N 2 , and zero for other species at the surface in the current simulations. This leads to the maximum surface chemistry contribution to heating and results in conservative heating predictions [3,28,32]. It is noted that radiative-equilibrium condition ignores the heat conduction through the TPS material, and supercatalytic wall forces all atoms to recombine to the freestream's value.…”

Section: Discretization and Boundary Conditionsmentioning

confidence: 99%

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Numerical study on the aerothermodynamics of different heatshield configurations for Mars entry capsules

et al. 2019

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Section: Discretization and Boundary Conditionsmentioning

confidence: 99%

Section: Discretization and Boundary Conditionsmentioning

confidence: 99%

Numerical study on the aerothermodynamics of different heatshield configurations for Mars entry capsules

et al. 2019

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“…Expansion tubes are used principally for the simulation of entry into planetary bodies from 6 to 12 km/s, [14][15][16][17][18][19][20][21][22][23] but the simulation of gas giant entry (where entry velocities range from 20 to 50 km/s) in an expansion tube is not a trivial task. The fact that the molecular weight of a simulated 85%H 2 /15%He (by volume) Uranus test gas mixture (2.31 g/mol) is 8% of the molecular weight of air (28.97 g/mol) gives the possibility of higher performance.…”

Section: Theoretical Condition Analysismentioning

confidence: 99%

“…The expansion tube is thought to be well suited to this task because this type of test facility is principally used for studying planetary entry phenomena for the other planets in our solar system. [14][15][16][17][18][19][20][21][22][23] This is because of the expansion tube's ability to accelerate a test flow to superorbital conditions without ionising it by processing the test flow with a shock wave and then an unsteady expansion instead of just a shock wave. 24 Primarily, this paper examines whether an expansion tube can be used to create test conditions relevant to the proposed missions to Uranus and Saturn [8][9][10] by using excess performance available from its high powered free piston driver, and the extra performance gained by using a light hydrogen and helium test gas.…”

Section: Introductionmentioning

confidence: 99%

Generating High Speed Earth Re-entry Test Conditions in an Expansion Tube for Interplanetary Return Missions

James¹,

Lewis²,

Gildfind³

et al. 2019

Proceedings of the 32nd International Symposium on Shock Waves (ISSW32 2019)

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In 2010, planetary entry probe missions to Uranus and Saturn were proposed. This paper details an investigation exploring the operating limits of the X2 superorbital expansion tube at the University of Queensland for the simulation of test conditions related to these proposed entries. Theoretical calculations showed that X2 could recreate the stagnation enthalpy of the proposed 22.3 km/s Uranus entry but not the stagnation enthalpy of the proposed 26.9 km/s Saturn entry. Experiments were able to confirm the theoretical performance calculations. However, losses caused some of the experimental shock speeds to be up to 10% slower than predicted, and due to the high velocity nature of the experiments, the shock speed errors were large making it difficult to properly quantify the test conditions. Further theoretical analysis investigated the possibility of using a more powerful free piston driver to simulate the Saturn entry conditions, and the analysis showed that with a slightly more powerful driver than X2's current most powerful configuration, the stagnation enthalpy of the proposed Saturn entry or other slightly faster entries proposed in the literature could be simulated. However, a very powerful driver would be required to recreate the stagnation enthalpies of these entries with the excess enthalpy needed to perform binary scaled experiments for an X2 sized facility.

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“…It is unclear how these CO2 thermochemical characteristics will differ under expanding flow conditions because not enough Hypersonics at the University of Queensland has both a reflected shock tube and an expansion tube (a synopsis of both facilities is presented in appendix A.4), the latter is selected as the preferred facility to perform the experiments. This is because, as stated by Maclean and Holden [51] and Hollis et al [81], the reflected shock tube is not suitable because the carbon dioxide conditions generated by the facility is believed to freeze at a complex non-equilibrium thermochemical state. This would result in a test condition with significant thermal excitation and a distorted chemical composition [82].…”

Section: Summary Of Findingsmentioning

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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Blunt-Body Aerothermodynamic Database from High-Enthalpy Carbon-Dioxide Testing in an Expansion Tunnel

Cited by 35 publications

References 21 publications

Numerical study on the aerothermodynamics of different heatshield configurations for Mars entry capsules

Numerical study on the aerothermodynamics of different heatshield configurations for Mars entry capsules

Generating High Speed Earth Re-entry Test Conditions in an Expansion Tube for Interplanetary Return Missions

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

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