Computational aerothermodynamic design issues for hypersonic vehicles

Olynick, David R.; Venkatapathy, Ethiraj

doi:10.2514/6.1997-2473

Cited by 43 publications

(33 citation statements)

References 109 publications

(77 reference statements)

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“…The design of thermal protection systems (TPS) presents a critical challenge for hypervelocity flight (Gnoffo 1996, Munk 2002. The issue first arose in the 1950"s when sustained supersonic flight became viable.…”

Section: Introductionmentioning

confidence: 99%

Radiation Measurements in Simulated Ablation Layers

Morgan¹

2010

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Report Documentation PageForm Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. REPORT DATE DEC 20102. REPORT TYPE In this study, radiation in ablating shocklayers over a scale Stardust model at 9 km/s was measured during the 80 μs steady test flow produced in a high enthalpy super-orbital expansion tunnel. The presence of an ablating shock layer when an epoxy coating is used with air and nitrogen test gases is shown by spectrometric and high speed camera data, and is in agreement with previous experimental results. Shock layer radiation is found to be strongest in the UV and visible portions of the electromagnetic spectrum, in both ablating and non-ablating shock layers. Shock layer radiation is greatly increased in ablating shock layers than in non-ablating shock layers when both air and nitrogen test gases are used. A nitrogen test gas is thought to produce a higher temperature shock layer than when air is used, implying that oxygen in air has a cooling effect on shocklayer radiation, due to the dissociation of the oxygen molecules which occurs. Shocklayer radiation in the near-IR is far weaker than that in the UV and consists of atomic, rather than molecular, transitions. As such, no distinct ablation layer is visible in the IR spectral data, however there is a doubling in radiance in the presence of an epoxy coating. SUBJECT TERMS Ablation, Thermal Environments, Reentry vehicles, Expansion tunnel AbstractThe interaction between an ablating shocklayer and radiative heat transfer to a surface, such as occurs on an ablating hypervelocity re-entry vehicle, is poorly understood. Ablative products act as absorbers and emitters, the net effect of which is strongly dependent on gas composition, enthalpy and wavelength. This paper presents the results of an experimental study investigating radiation in an ablating shocklayer over a 1:13.5 scale Stardust forebody model in an expansion tunnel in air, and nitrogen atmospheres at 9 km/s. The model was coated with a low-pyrolysis temperature hydrocarbon coating, permitting its thermal decomposition and the release of carbon-containing gaseous species into the shocklayer within the 80 μs test time. Shocklayer radiation is visualised using a high speed camera, whilst the emission spectra along the stagnation...

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Section: Introductionmentioning

confidence: 99%

Radiation Measurements in Simulated Ablation Layers

Morgan¹

2010

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“…The highest confidence in ground-based data and/or the pre-flight data book occurs when experimental and computational results are in full agreement. (Recent overviews of aerothermodynamic computational capabilities are provided by Kumar et al, 1997 andGnoffo et al, 1997. ) Flight experiments represent the third source of aerothermodynamic information (Fig.…”

Section: Sourcesmentioning

confidence: 99%

Aerothermodynamic flight simulation capabilities for aerospace vehicles

Miller

1998

20th AIAA Advanced Measurement and Ground Testing Technology Conference

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Aerothermodynamics, encompassing aerodynamics, aeroheating, and fluid dynamics and physical processes, is the genesis for the design and development of advanced space transportation vehicles and provides crucial information to other disciplines such as structures, materials, propulsion, avionics, and guidance, navigation and control. Sources of aerothermodynamic information are ground-based facilities, Computational Fluid Dynamic (CFD) and engineering computer codes, and flight experiments. Utilization of this aerothermodynamic triad provides the optimum aerothermodynamic design to safely satisfy mission requirements while reducing design conservatism, risk and cost. The iterative aerothermodynamic process for initial screening/assessment of aerospace vehicle concepts, optimization of aerolines to achieve/exceed mission requirements, and benchmark studies for final design and establishment of the flight data book are reviewed. Aerothermodynamic methodology centered on synergism between ground-based testing and CFD predictions is discussed for various flow regimes encountered by a vehicle entering the Earth's atmosphere from low Earth orbit. An overview of the resources/infrastructure required to provide accuratekreditable aerothermodynamic information in a timely manner is presented. Impacts on Langley's aerothermodynamic capabilities due to recent programmatic changes such as Center reorganization, downsizing, outsourcing, industry (as opposed to NASA) led programs, and so forth are discussed. Sample applications of these capabilities to high

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“…"Aerothermodynamics couples the disciplines of aerodynamics and thermodynamics" (Gnoffo et al 1999). The flow field for a vehicle that flies at hypersonic speeds is one in which high-temperature gas effects strongly influence the forces acting on the surface (the pressure and the skin friction) and the energy flux (the convective and the radiative heating).…”

Section: Introductionmentioning

confidence: 99%

Critical Hypersonic Aerothermodynamic Phenomena

Bertin

Cummings

2006

Annu. Rev. Fluid Mech.

237

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The challenges in understanding hypersonic flight are discussed and critical hyper sonic aerothermodynamics issues are reviewed. The ability of current analytical meth ods, numerical methods, ground testing capabilities, and flight testing approaches to predict hypersonic flow are evaluated. The areas where aerothermodynamic short comings restrict our ability to design and analyze hypersonic vehicles are discussed, and prospects for future capabilities are reviewed. Considerable work still needs to be done before our understanding of hypersonic flow will allow for the accurate pre diction of vehicle flight characteristics throughout the flight envelope from launch to orbital insertion.

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Computational aerothermodynamic design issues for hypersonic vehicles

Cited by 43 publications

References 109 publications

Radiation Measurements in Simulated Ablation Layers

Radiation Measurements in Simulated Ablation Layers

Aerothermodynamic flight simulation capabilities for aerospace vehicles

Critical Hypersonic Aerothermodynamic Phenomena

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