Assessment of Hypersonic Double-Cone Experiments for Validation of Thermochemistry Models

Holloway, Michael E.; Chaudhry, Ross S.; Boyd, Iain D.

doi:10.2514/1.a35052

Cited by 19 publications

(4 citation statements)

References 30 publications

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“…Further prediction attempts completed [5][6][7][8] still show difficulties in predicting the flow separation lengths with attempts of uncertainty analysis [9] also completed to try and reach a conclusion. There are further datasets that were added to the mix such as the work conducted at Caltech T5 by Knisley and Austin [10], and the experiments at the Arnold Engineering Development Center (AEDC) tunnel no.…”

Section: Introductionmentioning

confidence: 99%

Measurements of Hypersonic Double Cone Flows with Shock Wave/Boundary Layer Interactions in the X3 Expansion Tunnel

Kennedy

McGilvray

James

et al. 2023

AIAA SCITECH 2023 Forum

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This paper presents the results from a series of hypersonic double cone experiments, conducted in the X3 expansion tunnel at the University of Queensland (UQ). The model was previously used and produced at California Institute of Technology (Caltech) and is a scaled model of the double cone model used by the Calspan-University of Buffalo Research Center (CUBRC). The data presented is a full transient set of surface heat flux, and surface pressure measurements along the axial length of the model as well as a full suite of tunnel data. These aim to help characterize the flow over the geometry by providing surface conditions, an accurate location of the boundary layer separation, the flow reattachment points and the general structure of the shockwave boundary layer interaction. The geometry of the X3 facility is also provided to give a more complete picture of the test conditions, an important consideration for numerical models. The outcome of this paper is to provide the most detailed experimental data to date and improve validation attempts of existing non-equilibrium thermochemistry codes.

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Section: Introductionmentioning

confidence: 99%

Measurements of Hypersonic Double Cone Flows with Shock Wave/Boundary Layer Interactions in the X3 Expansion Tunnel

Kennedy

McGilvray

James

et al. 2023

AIAA SCITECH 2023 Forum

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“…Various models and rates exist, but, due to the lack of appropriate experimental data, it is still rather unclear which of these existing models and rates are accurate, if any. 61 Even the high-fidelity state-to-state (StS) models, in which each molecular vibrational state is considered a pseudo-species, have significant uncertainties due to the uncertainties in the state-specific rates used, which can differ by orders of magnitude between different sources. 62 Thus, accurate modeling of thermochemical nonequilibrium remains an open problem and is very much an active area of research.…”

Section: Uncertainty From the Nonequilibrium Modelmentioning

confidence: 99%

Influence of thermochemical nonequilibrium on expansion tube air test conditions: A numerical study

Hao

Wang

et al. 2023

Physics of Fluids

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Using a Lagrangian solver, thermochemical nonequilibrium simulations are performed for the entire range of practical operating conditions of expansion tubes to isolate the influence of nonequilibrium and identify key features in large-scale facilities. Particular attention is given not only to the influence of the nonequilibrium unsteady expansion but also to the influences of the nonequilibrium region behind the primary shock and non-ideal secondary diaphragm rupture. The nonequilibrium unsteady expansion is found to be the most influential process on the test flow - it can significantly influence the flow properties and cause significant temporal variations in the properties during the test time. The nonequilibrium unsteady expansion is also found to accelerate the secondary shock and contact surface. The non-ideal secondary diaphragm rupture is found to increase the amount of nonequilibrium in the test flow due to the generation of a reflected shock. The nonequilibrium region behind the primary shock may be considered negligible in most conditions. Regarding the creation of thermochemical equilibrium test conditions, important factors for achieving this include having a high acceleration tube fill pressure, large-scale facility, and high total enthalpy. The combined effects of viscosity and nonequilibrium are postulated, and the results are supported by experimental works which report consistent findings. To provide an idea of the sensitivity of the numerical configuration, simulations of fixed-volume reactors at various de-excitation conditions are performed using different nonequilibrium models.

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“…This prompted uncertainty quantification analyses to verify that the stated experimental conditions were consistent with the measurements (Ray et al 2020). Also, the numerical predictions for many runs appeared to be rather insensitive to the thermochemical models and the small variations were not enough to account for the differences with experiments (Kianvashrad & Knight 2019;Holloway, Chaudhry & Boyd 2022). Finally, the experimental run time (around 1 ms) was brought into question as insufficient to establish a steady-state flow over the double cone (Tumuklu et al 2018a).…”

Section: Introductionmentioning

confidence: 97%

Near-continuum, hypersonic oxygen flow over a double cone simulated by direct simulation Monte Carlo informed from quantum chemistry

et al. 2023

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A large-scale, fully resolved direct simulation Monte Carlo (DSMC) computation of a non-equilibrium, reactive flow of pure oxygen over a double cone is presented. Under the simulated near-continuum conditions, the computational demands are shown to be significant because of the wide range of length scales that must be resolved. Therefore, robust grid adaption capabilities and efficient parallelization of the Stochastic PArallel Rarefied-gas Time-accurate Analyzer (SPARTA) code that is utilized in this work are essential. The thermochemical and transport collision models were selected for efficiency and simplicity. First-principles data, obtained from the highly accurate direct molecular simulation method, were used to inform the collision models’ parameters. Importantly, because SPARTA implements molecular collision models using collision-specific energies, the resulting macroscopic relaxation rates were evaluated a posteriori via zero-dimensional heat bath simulations. The comparisons of surface properties, namely heat flux and pressure, show very close agreement with previous computational fluid dynamics (CFD) results. Differences with the measurements were found to be similar to the CFD simulations. The unresolved discrepancy with the measurements could be due to inconsistent free stream conditions with the actual experimental data or missing physical phenomena altogether, for example atomic and molecular oxygen electronically excited states, three-dimensional effects, or more complex gas–surface interactions. As shown in this work, the advantages of obtaining a DSMC particle solution for these flows reside in the method's ability to be directly informed from first principles and to seamlessly describe internal energy non-equilibrium for all modes. With the advent of exascale computing and beyond, particle methods will be an increasingly important tool to verify the validity of physical assumptions in reduced-order models via fully resolved, experimental-scale simulations, down to the level of molecular-level distributions.

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Assessment of Hypersonic Double-Cone Experiments for Validation of Thermochemistry Models

Cited by 19 publications

References 30 publications

Measurements of Hypersonic Double Cone Flows with Shock Wave/Boundary Layer Interactions in the X3 Expansion Tunnel

Measurements of Hypersonic Double Cone Flows with Shock Wave/Boundary Layer Interactions in the X3 Expansion Tunnel

Influence of thermochemical nonequilibrium on expansion tube air test conditions: A numerical study

Near-continuum, hypersonic oxygen flow over a double cone simulated by direct simulation Monte Carlo informed from quantum chemistry

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