Effect of non-equilibrium thermochemistry on Pitot pressure measurements in shock tunnels (or: Is 0.92 really the magic number?)
Article
Article Title | Effect of non-equilibrium thermochemistry on Pitot pressure measurements |
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ERA Journal ID | 3572 |
Article Category | Article |
Authors | Sopek, Tamara, Jacobs, Peter, Subiah, Suria-Devi, Collen, Peter and McGilvray, Matthew |
Journal Title | Acta Astronautica |
Journal Citation | 223, pp. 249-261 |
Number of Pages | 13 |
Year | 2024 |
Publisher | Elsevier |
Place of Publication | United Kingdom |
ISSN | 0094-5765 |
1879-2030 | |
Digital Object Identifier (DOI) | https://doi.org/10.1016/j.actaastro.2024.07.008 |
Web Address (URL) | https://www.sciencedirect.com/science/article/pii/S009457652400376X |
Abstract | Pitot pressure is the most common measurement in high total enthalpy shock tunnels for test condition verification. Nozzle calculations using multi-temperature non-equilibrium thermochemistry are needed in conjunction with Pitot measurements to quantify freestream properties. Pitot pressure is typically matched by tuning the boundary layer transition location in these simulations. However, non-equilibrium thermochemistry effects on the Pitot probe are commonly ignored. A computational study was undertaken to estimate the effect of non-equilibrium thermochemistry on Pitot pressure and freestream conditions. The test flow was produced by a Mach 7 nozzle in a reflected shock tunnel for air at a relatively low total enthalpy of 2.67 MJ/kg. Three different thermochemical models (equilibrium, finite-rate chemistry and two-temperature thermochemistry) were employed to compute flow variables at the nozzle exit and Pitot probe. Pitot pressures from these simulations were compared against those obtained via experiments. The results show a departure from the commonly utilized đ¶ of 0.92 in the reduced Rayleigh-Pitot equation form for high Mach numbers. Additionally, calculations were done with a sweep of free-stream conditions and resulting in values for one- and twotemperature models to use in future shock tunnel studies. Overall, our results show that the influence of finite-rate thermochemistry should be taken into account, even at relatively low flow enthalpies. |
Keywords | Pitot pressure; Fluid mechanics; Hypersonics; Shock tunnel; Computational fluid dynamics |
Contains Sensitive Content | Does not contain sensitive content |
ANZSRC Field of Research 2020 | 400106. Hypersonic propulsion and hypersonic aerothermodynamics |
400199. Aerospace engineering not elsewhere classified | |
401204. Computational methods in fluid flow, heat and mass transfer (incl. computational fluid dynamics) | |
Byline Affiliations | University of Southern Queensland |
University of Oxford, United Kingdom |
https://research.usq.edu.au/item/z85zq/effect-of-non-equilibrium-thermochemistry-on-pitot-pressure-measurements-in-shock-tunnels-or-is-0-92-really-the-magic-number
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Sopek2024b_Effect_of_nonequilibrium_thermochemistry_on_Pitot_pressure_measurements_in_shock_tunnels.pdf | ||
License: CC BY 4.0 | ||
File access level: Anyone |
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