Expansion Tunnel Radiation Experiments to Support Hayabusa Re-Entry Observations

Buttsworth, David; D’Souza, Mary; Potter, Daniel; Eichmann, Troy N.; Mudford, N. R.; McGilvray, Matthew; McIntyre, Timothy J.; Jacobs, Peter A.; Morgan, Richard G.

doi:10.2514/6.2010-634

Cited by 10 publications

(7 citation statements)

References 2 publications

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“…Due to the brittleness of the phenolic resin, electrical preheating of the model was abandoned in favor of shock heating, which was similar to Buttsworth et al [5], i.e., the hot flow increased the surface temperature and caused the model to decompose. The thermal diffusivity of a typical carbon-phenolic TPS is α ∼ 10 −6 m 2 ⋅ s −1 [18], giving a penetration distance of approximately 8αt test p ∼ 24 μm for a steady test time of t test ∼ 70 μs.…”

Section: B Model Development and Bench Testingmentioning

confidence: 80%

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Venus Entry Flow over a Decomposing Aeroshell in X2 Expansion Tube

Banerji¹,

Leyland²,

Fahy³

et al. 2018

Journal of Thermophysics and Heat Transfer

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The effects of phenolic decomposition on shock-layer radiation were investigated experimentally in X2 expansion tube for a Venus entry flow. A carbon-phenolic composite aeroshell was subjected to a flow with a flight equivalent velocity of 9.35 km ⋅ s −1 . Emission spectroscopy was used to measure boundary-layer radiation in parts of the ultraviolet (380-480 nm) and visible (620-700 nm) spectrum, and it was compared to control measurements taken with a cold steel model. With the composite model in place, the calibrated spectral radiance measured was seen to increase for the O (645.598 nm) atomic line and the N 2 (391.22 nm) band head, but it decreased for the C 2 Swan band (420-480 nm). The recorded data were then compared to numerical spectra produced by two-dimensional axisymmetric computational fluid dynamic simulations coupled to a radiation solver. Both of the applied chemistry models overpredicted CN violet Δν 0 band radiation, which demonstrated strong self-absorption at these conditions. Better comparisons were achieved for the C 2 Swan band radiation. At visible wavelengths, peak intensities were underestimated by the numerical simulations. Several possible reasons were hypothesized for these discrepancies.

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Section: B Model Development and Bench Testingmentioning

confidence: 80%

“…The effects of ablation on air shock layers have been the subject of several previous test campaigns in X2 expansion tube at the University of Queensland in Australia. Buttsworth et al [5] tested scaled stainless-steel models of the Hayabusa capsule that were layered with an epoxy resin. Upon encountering the hot hypersonic flow, the resin started to pyrolyze.…”

mentioning

confidence: 99%

Venus Entry Flow over a Decomposing Aeroshell in X2 Expansion Tube

Banerji¹,

Leyland²,

Fahy³

et al. 2018

Journal of Thermophysics and Heat Transfer

Self Cite

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“…The UV spectra was made more interesting by the addition of an epoxy layer over the steel model, in an attempt to replicate ablation and pyrolysis from the vehicle surface and produce CN. The calibrated comparison between the standard air shock layer and the shock layer with added species shows that the bands and bandheads between 350 and 400 nm do increase for the epoxy coated models, but only by at most double the height, and the N + 2 bandhead at 391 nm has not been clearly resolved to show a distinct species from the air shock layer [63]. An attempt was also made to measure the luminosity of the shock layer from visible emissions captured by the high-speed camera, but these are uncalibrated and only show the relative emission strength across the shock layer [64].…”

Section: Relevant X2 Experimental Campaignsmentioning

confidence: 99%

“…The most relevant overall campaign to the aim and objectives of this project was the campaign performed by Buttsworth et al on a scaled Hayabusa model prior to the re-entry [63]. A one-tenth scale aeroshell model that maintained the geometry of the Hayabusa flight vehicle was tested with an approximate effective flight speed of 9.7 km · s −1 [63].…”

Section: Relevant X2 Experimental Campaignsmentioning

confidence: 99%

“…A one-tenth scale aeroshell model that maintained the geometry of the Hayabusa flight vehicle was tested with an approximate effective flight speed of 9.7 km · s −1 [63]. The UV spectra was made more interesting by the addition of an epoxy layer over the steel model, in an attempt to replicate ablation and pyrolysis from the vehicle surface and produce CN.…”

Section: Relevant X2 Experimental Campaignsmentioning

confidence: 99%

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Superorbital re-entry shock layers: flight and laboratory comparisons

Fahy¹

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Hypervelocity re-entry through the Earth's atmosphere surrounds an aeroshell with a radiating shock layer, which has complex and potentially critical interactions with the thermal protection system, the key component to the vehicle's survival. Aerothermodynamic re-entry flight data is rare, but the available radiation data has potential for replication in ground-based experimental and numerical testing, where flight equivalent conditions can be achieved. A greater understanding and ability to demonstrate the behaviour of re-entry vehicles will allow increased confidence in pre-flight laboratory predictions, design iterations based on testing and simulation, and an overall reduction in the thermal protection system (TPS) mass, therefore increasing the mass available for scientific payload. This thesis aims to replicate flight data from the unmanned Hayabusa and Stardust aeroshell re-entries in expansion tube experiments and numerical simulations, and assess the similarities and differences in the results. The flight data is in the form of infrared (IR) and ultraviolet (UV) spectra emanating from the bow shock, as captured by air-and ground-based observation missions.The experiments were performed in the X2 expansion tube, a hypervelocity impulse facility capable of producing flight equivalent conditions over a scaled aeroshell model for a brief test time. Prior to optical imaging tests, the conditions were designed through an iterative combination of analytical, experimental and numerical methods, based on binary scaling and enthalpy matching. Emissions from the radiating shock layers were captured by IR and UV spectroscopy, as well as two-dimensional intensity mapping through a narrow wavelength band filter, but the measurements were oriented differently to flight. The axisymmetry of certain imaging planes enabled the transformation of line of sight integrated intensities into radial quantities, which could describe the forebody shock layer and result in an integrated intensity comparable with integrated flight spectra.Numerical simulations must first model the flowfield before radiation modelling is possible. Compressible flow computational fluid dynamics (CFD) simulations were performed for the Hayabusa and Stardust flight vehicles at the selected trajectory points, and scaled models at idealised and simulated inflow conditions. Radiation spectra calculations were performed along the same lines of sight as imaged in experimental spectra, and over the entire flowfield to be comparable to flight data and experimental 2D imaging.iii The flight, experimental and numerical data combined for a series of comparisons to test the hypotheses that under binary scaling, spectral radiance along a line of sight is invariant, and radiative intensity scales with the square of the length scale. Spectra comparisons between experiment and CFD, and CFD and flight, tested the first hypothesis, and integrated intensity comparisons between experiment and CFD, and experiment and flight, tested the second hypothesis. Favourabl...

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