Low-Reynolds-Number Effects on Hypersonic Blunt-Body Shock Standoff

Inger, G. R.

doi:10.2514/1.9157

Cited by 4 publications

(9 citation statements)

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“…First, the exact value of ∆ cannot be known prior to the test and has thus to be estimated through numerical simulations or using correlations. Second, the post-shock density ρ is not constant but will along the stagnation line due to changes in the chemical composition of the flow [81,86,87,207]. Alternatively, another expression, easier to handle than ρ∆, is ρ ∞ L, where L is a transverse length-scale of the hypersonic vehicle, such as the nose radius.…”

Section: Final Formmentioning

confidence: 99%

“…One of the most comprehensive semi-empirical correlation for constant density inviscid shock layers was suggested by Inger [86], who accounted for the flow's vortical properties:…”

Section: Relation Between Shock Standoff and Density Ratiomentioning

confidence: 99%

“…However, in rarefied regime the boundary layer can become substantially large and have an impact on the rest of the flow. Inger points out that these viscid-inviscid interactions have a negligible influence on the shock standoff distance for Reynolds numbers larger than 300, but should be taken into account otherwise [86]. He defines the shock layer Reynolds number Re fr as:…”

Section: Viscid-inviscid Interactionsmentioning

confidence: 99%

“…The pressure is assumed constant throughout the shock layer. From that approach, he shows analytically that, assuming a frozen flow, the viscid shock standoff distance can be simplified to [86]:…”

Section: Viscid-inviscid Interactionsmentioning

confidence: 99%

“…The shock standoff distance is both easy to measure and, as discussed in section 3.2, a good indicator of the vibrational and chemical state of the shock layer. As a consequence, there is plenty of data available in the literature, and as many empirical or semi-empirical correlations, for the evolution of shock standoff distance with respect to probe geometry and free-stream conditions [5,12,14,75,81,86,87,110,132,201,207,212]. However, as noted by Zander et al [212], most of that data was obtained in the low-speed hypersonic regime, i.e.…”

Section: Test Conditions For Venus Atmospheric Entrymentioning

confidence: 99%

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On binary scaling and ground-to-flight extrapolation in high-enthalpy facilities

Looringhe¹,

Arwid²

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The binary scaling law is commonly used to study the aerothermodynamics of hypersonic vehicles in high-enthalpy facilities. It enables the duplication of the shock layer in the vicinity of the stagnation point, including binary chemistry and nonequilibrium processes, through the reproduction of the Péclet and wall Damköhler numbers. These are both conserved through the duplication of the composition of the gas, the free-stream enthalpy h ∞ and the product of a density and a length-scale of the flow ρL.Binary scaling is built on the assumption of a flow devoid of radiation coupling and governed by binary reactions. These two conditions drastically narrow down the envelope of flows for which binary scaling can be used. Moreover, diffusive transport and wall chemistry have never been addressed although they can have an important impact on the wall heat flux.The first part of this thesis consists in an effort to better understand the theoretical role and effect of the different assumptions done to build the binary scaling. It is first shown that diffusive transport and wall chemistry should scale appropriately. Second, that non-binary chemistry will cause the shock layer in the laboratory flow to be hotter and less dissociated. A methodology is proposed to identify clearly what free-stream conditions will affect the least the flow variables of interest. Lastly, that radiation coupling will be weaker in the laboratory flow than in flight, causing the enthalpy contained in the shock layer to be greater in the laboratory flow.These findings are verified in the second part with two experiments. The first experiment was performed in the Plasmatron plasma wind tunnel at the von Karman Institute, Belgium. Binary scaled boundary layers were obtained for flows where diffusion and wall chemistry contribute significantly to the heat flux. The stagnation point heat fluxes were measured and exhibit a good agreement with the theoretical scaling law. This also validates the use of the binary scaling law in subsonic high-enthalpy facilities.The second experiment was performed in the X2 expansion tube at the Centre for Hypersonics, Australia. Three flows were obtained over cylinders of different radii, adapting the free-stream density according to the binary scaling law. The free-stream conditions were determined in order to ensure a significant radiative coupling. Its effect could clearly be identified through measurements of the shock standoff distance, stagnation point heat flux, and shock layer radiation. A new method, based on a mix of experiments, computational fluid dynamics, and informed use of engineering correlations is proposed to perform ground to flight extrapolation for cases for which the radiative coupling is non-negligible. Declaration by authorThis thesis is composed of my original work, and contains no material previously published or written by another person except where due reference has been made in the text. I have clearly stated the contribution by others to jointly-authored works that I have include...

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Section: Final Formmentioning

confidence: 99%

“…One of the most comprehensive semi-empirical correlation for constant density inviscid shock layers was suggested by Inger [86], who accounted for the flow's vortical properties:…”

Section: Relation Between Shock Standoff and Density Ratiomentioning

confidence: 99%

Section: Viscid-inviscid Interactionsmentioning

confidence: 99%

Section: Viscid-inviscid Interactionsmentioning

confidence: 99%