The thermal protection system of a reentry vehicle must endure extreme heating loads, leading to high surface temperatures and associated phenomena such as thermochemical ablation. Accurate modeling prediction these processes are critical for determining heat-shield sizing requirements; however, large uncertainties still remain. Due the costs with flight tests, ground testing remains an economical option addressing uncertainties. In this study, experiments electrically preheated graphite...

Vehicles entering planetary atmospheres at high speed require an ablative heat shield to withstand the thermal energy flux body. The interaction between products and flowfield is not well characterized. In this study, numerical simulations were conducted investigate influence of carbon ablation on shock-layer radiation. Data collected from experiments performed in X-2 expansion tunnel University Queensland used compare simulations. model was a short half-cylinder made isomolded graphite...

Despite the prominence of carbon-based materials for use in thermal protection systems, much uncertainty remains predicting thermochemical ablation rates at high surface temperatures. To address this issue, experiments using preheated graphite models with temperatures up to 3300 K were conducted X2 expansion tunnel University Queensland. Calibrated shock-layer emission measurements wavelength region from 353 391 nm taken observe effect temperature on radiation CN violet and bands. Numerical...

This correction pertains to minor elements that were in error the original article when it was first published online [https://doi.org/10.2514/1.J056021]. On page, third author’s middle initial incorrect. The correct full name is Steven W. Lewis.

Experiments studying carbon ablation were performed with electrically heated graphite strips embedded into a steel base structure. The test articles exposed to hypervelocity air and nitrogen flows investigate previously proposed coupling effect of surface monoxide production on the levels cyanogen via gas phase reactions. Based relative emissions between two conditions, it was concluded that, although interactions nonnegligible contributor production, majority due direct nitridation. In...

Thermography for measuring high temperatures, ranging from 1000 to 2900 K, in hypersonic preheated ablation experiments is demonstrated this work. Filtered images at different wavelengths were acquired obtain temperature maps by two methods: dual-wavelength signal ratio and multiwavelength Planck fit. This technique was applied measurements of resistively heated graphite ablators used performed the X2 super-orbital expansion tube The University Queensland, Australia. Six narrow band pass...

Flight into the gas giant planets involves atmospheric entry velocities between 20 and , which are mostly beyond capabilities of current ground testing facilities that make use test models. Using an expansion tube, this paper investigates how increasing percentage helium in gas, or substituting for heavier noble neon, can be used to generate representative shock-layer conditions associated with Uranus Saturn entry. Theoretically, it was found either substitution should possible simulate...

Despite the prominence of carbon-based materials for use in thermal protection systems,much uncertainty remains predicting thermochemical ablation rates at high surface temperatures. To address this issue, a series experiments using pre-heated graphite models with temperatures up to 3280 K was conducted X-2 expansion tunnel The University Queensland. Calibrated shock-layer emission measurements wavelength region from 353 391 nm were taken observe effect temperature on radiation CN Violet ∆v...

In this study an expansion tube is used to generate experiment and evaluate the concept of magnetohydrodynamic aerobraking for planetary entry spacecraft. An can theoretically required hypersonic flowfield within which ionisation confined shock layer; important characteristic true flight case previous experiments with arcjets have failed achieve. The first part paper explores operating envelope University Queensland’s X2 facility, identify flow conditions should produce a significant...

The ablating species from the thermal protection systems upon atmospheric entry interact with atomic/molecular gas in shock layer and form new products that affect total radiation. In this work, ablation of carbon was experimentally studied by resistively preheating graphite strips to representative reentry wall temperatures exposing them hypervelocity Earth-entry flow conditions generated X2 expansion tube facility at University Queensland, Australia. were mounted on a compression wedge...

In 2010, planetary entry probe missions to Uranus and Saturn were proposed. This paper details an investigation exploring the operating limits of X2 superorbital expansion tube at University Queensland for simulation test conditions related these proposed entries. Theoretical calculations showed that could recreate stagnation enthalpy 22.3 km/s but not 26.9 entry. Experiments able confirm theoretical performance calculations. However, losses caused some experimental shock speeds be up 10%...

This study presents calibrated vacuum ultraviolet spectroscopic measurements and filtered cyanogen violet band images for steel, cold graphite, preheated graphite models at three reentry-relevant conditions in the X2 Expansion Tube. An analysis of these experiments concluded that there were no unique radiating species boundary layer an ablating model within spectral range 120–180 nm. Spectral showed increase atomic carbon emission with models. Filtered revealed significant A comparison...

Atmospheric entry to the Gas Giants involves velocities from 20 - 50 km/s, which is mostly beyond capabilities of current ground testing facilities. This paper details an investigation exploring operating limits X2 superorbital expansion tube at University Queensland (UQ) for simulation radiating gas giant flow condi- tions. Theoretical calculations show that can simulate a proposed Uranus 22.3 km/s but falls below necessary 26.9 velocity Saturn probe mission. An experimental analysis was...

In 2010, the U.S. National Research Council proposed planetary entry probe missions to Uranus and Saturn. This paper details an investigation exploring operating limits of X2 superorbital expansion tube at University Queensland for simulation atmospheric test conditions related these missions. Theoretical calculations indicate that can recreate stagnation enthalpy entry, but not Saturn entry. Experiments were generally able confirm theoretical predictions; however, internal loss mechanisms...

Get PDF Email Share with Facebook Tweet This Post on reddit LinkedIn Add to CiteULike Mendeley BibSonomy Citation Copy Text Roland C. Anderson and Steven Lewis, "Flow visualization by dark central ground interferometry," Appl. Opt. 24, 3687-3687 (1985) Export BibTex Endnote (RIS) HTML Plain alert Save article

Future space missions, such as return from Mars, will require entry speeds of the order . These harsh conditions are dominated by radiative heat flux and have large modeling uncertainties related to coupling, precursor radiation ablation coupling. also never been tested in a flight scenario limited ground testing data available. This study investigates feasibility generating these X2 expansion tube at University Queensland so that flows can be over scaled test models for shock relaxation,...

Traditionally, Pitot rake test models have been used to take time and spatially resolved pressure measurements in impulse facilities for flow characterisation. These allow the section gas state be inferred using analytical more complex computational models. They also provide an indication of experimental core diameter. However, being based on only one variable, they are not definitive, this gives motivation developing methods other variables. When expansion tubes study hypervelocity...

Hypervelocity aerothermodynamic processes which occur during atmospheric re-entry scenarios, are very complex with regards to the coupled fluid dynamic-chemistry interactions and resulting heat transfer mechanisms and ablation rates. Current thermal protection systems rely on large safety factors cope these uncertainties. These uncertainties will be addressed through a new experimental setup in X2 expansion tunnel at University of Queensland. A flat plate mount an interchangeable,...