Viscous Shock-Layer Simulation of Airflow past Ablating Blunt Body with Carbon Surface

Zhluktov, Sergey V.; Abe, Takashi

doi:10.2514/2.6400

Cited by 116 publications

(63 citation statements)

References 20 publications

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“…A generalized version of the surface chemistry formulation given in Zhluktov and Abe 12 begins with the expression for a single chemical reaction:…”

Section: Surface Kinetic Modelingmentioning

confidence: 99%

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Thermo-chemical ablation during reentrant and high altitude skipping flight

Havstad

Carter

2001

39th Aerospace Sciences Meeting and Exhibit

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Thermo-chemical ablation during reentrant and high altitude skipping flights is treated using a variety of techniques. The solid material response is computed using heat-balance integrals, finite differences, and finite elements. The surface mass loss is computed using curve fits to the standard transport coefficient approach and by a surface kinetic model. Agreement between the approaches, when using the curve fits, is good. All approaches concur that for the skipping trajectory studied there is very little mass loss and surface temperatures remain in a range where the thermal protection system can be reused.

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“…A generalized version of the surface chemistry formulation given in Zhluktov and Abe 12 begins with the expression for a single chemical reaction:…”

Section: Surface Kinetic Modelingmentioning

confidence: 99%

“…Aspects of the operative surface thermochemistry are summarized in a fairly recent review 9 . Some of the more recent work has focused on surface kinetics 10,11,12 . However, integrating detailed kinetic models with both material response and flow field calculations is a challenge.…”

Section: Introductionmentioning

confidence: 99%

Thermo-chemical ablation during reentrant and high altitude skipping flight

Havstad

Carter

2001

39th Aerospace Sciences Meeting and Exhibit

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“…Significant deviations can be expected at temperatures above 2000 K where non-Arrhenius behaviour is observed. It should be noted that this behaviour is also not captured in the ZA model, as it assumes a pure-graphite surface with no impurities and therefore only one type of reaction zone [36].…”

Section: Oxidationmentioning

confidence: 99%

“…It should be highlighted that molecular adsorption and nitridation are not included. For a full description of the rate equations and constants, the reader is referred to the original publication by Zhluktov and Abe [36].…”

Section: Zhluktov and Abe Modelmentioning

confidence: 99%

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Hypervelocity shock layer emission spectroscopy with high temperature ablating models

Lewis¹

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During reentry into the atmosphere, a vehicle can encounter extreme convective and possibly radiative heating loads. Such spacecraft must rely on a carefully designed thermal protection system to maintain the integrity of the underlying structure, thus ensuring the survival of any cargo or crew it may contain. Despite many past developments and research efforts, to this day there remain large uncertainties associated with the prediction of heat shield performance. In particular, accurate modelling of ablation phenomena is critical to minimising uncertainties, reducing excess weight, and increasing safety. This includes thermochemical ablation by oxidation, nitridation, and sublimation, as well as the mechanical removal of material via spallation. Due to the high costs associated with in-flight testing, and the difficulty of mounting precision instruments and advanced diagnostics on flight vehicles, ground-based experiments stand as a cost-effective method for reducing modelling uncertainties.Ablation testing is generally conducted in long-duration facilities such as arc jets, which are well suited to investigating in-depth material response due to their ability to provide representative heating rates for extended periods. They are, however, unable to reproduce a realistic in-flight shock layer due to low Reynolds numbers and, depending on the facility type, a high degree of thermal and chemical nonequilibrium in the free-stream. In contrast, impulse facilities such as shock tubes and their variants are well suited to reproducing realistic flight conditions with free-streams that are a closer match for flows dominated by binary processes in terms of Reynolds number, temperature, and chemical composition. Due to their extremely short test times, however, ranging from the order of 10 µs to several milliseconds, they are unable to aerothermally heat test models up to representative in-flight temperatures, or recreate the quasi-steady heat and mass flux balance of flight. This key limitation of impulse facilities was recently overcome in experiments using the University of Queensland's X2 expansion tunnel by electrically pre-heating samples to temperatures approaching 2500 K immediately prior to a test.In this work, the pre-heating methodology was enhanced to generate maximum surface temperatures approaching 3300 K in order to study sublimation phenomena. It was found that although sublimation-regime temperatures could be achieved, the relevant surface processes themselves were suppressed due to the high pitot pressures of the conditions used. Instead, the nitridation process was studied by observing air shock layer CN emissions with pure graphite models heated to surface temperatures ranging from 1770-3300 K. These results were compared with numerical simulations which predicted a monotonic increase of emissions with surface temperature for all models considered, whereas the experiments showed an initial increase from 1770-2500 K and then remained relatively constant from 2500-3300 K. The simulations also su...

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