Cryogenic nitrogen as a transonic                                                   wind-tunnel test gas

Adcock, J. B.; Kilgore, R. A.; Ray, E. J.

doi:10.2514/6.1975-143

Cited by 11 publications

(6 citation statements)

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“…It is worth noting that the isentropic relation for real gases does not align perfectly with Equation (3). For simplicity, pressure and density can still be related using the same equation, albeit with a different expansion coefficient denoted as α [2]. Therefore, the isentropic relation can be reformulated as…”

Section: Isentropic Expansion Of Cryogenic Nitrogenmentioning

confidence: 99%

“…The primary solution to address the challenge of low Reynolds numbers in large wind tunnels involves integrating cryogenic technology with wind tunnel systems, resulting in the creation of cryogenic wind tunnels. These specialized wind tunnels typically employ nitrogen as the test gas [1,2]. In comparison to conventional wind tunnels, cryogenic wind tunnels raised pressure levels, and the reduced temperature led to a lower viscosity of the test gas.…”

Section: Introductionmentioning

confidence: 99%

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The Influence of Gas Models on Numerical Simulations of Cryogenic Flow

Hu,

Chen,

et al. 2023

Aerospace

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At cryogenic temperatures, gases exhibit significant deviations from ideal behaviour, and the commonly employed gas model may inadequately represent the thermodynamic properties of cryogenic gases, subsequently impacting numerical simulations using various thermodynamic and transport models at cryogenic temperatures. The findings of this study reveal that the relative errors in aerodynamic characteristics obtained through different isentropic relations are noteworthy, with the maximum relative error in the drag coefficient reaching 16%. The impact of the equation of state, viscosity model, and thermal conductivity model is relatively minor, with relative errors in the pressure drag coefficient and viscous drag coefficient remaining well below 1%. Nevertheless, the relative error in the skin friction coefficient cannot be ignored due to transonic shock wave/boundary layer interactions. Consequently, when conducting numerical simulations of cryogenic flow, it is imperative to select appropriate gas models to attain precise results.

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Section: Isentropic Expansion Of Cryogenic Nitrogenmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Influence of Gas Models on Numerical Simulations of Cryogenic Flow

Hu,

Chen,

et al. 2023

Aerospace

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“…Submitted Sept. 4,1979. This paper is declared a work of the U.S. Government and therefore is in the public domain.…”

Section: Application Of Unsteady Airfoilmentioning

confidence: 98%

Simulation of flat-plate turbulent boundary layers in cryogenic tunnels

Adcock

1980

Journal of Aircraft

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rather than nosing down into a dive at too low an altitude to complete the recovery. lj2 In a canard, it is awkward to mount a vertical stabilizer far enough aft to produce adequate weathercock stability. However, if inherent stability is dispensed with in yaw as well as in pitch, the weathercock effect is no longer needed and the necessary control moment in yaw can be generated by a contjrol surface at the front. SummaryAutomatic, as opposed to inherent, stability permits the center of gravity of an aircraft to be shifted aft, thus improving the vehicle's lift/drag ratio and maneuverability. However, the increased loading on the rear surface, if carried far enough to optimize the apportioning of load between front and rear, will make the rear surface prone to stall and can lead to pitching moments which may be difficult or impossible to control. This danger can be avoided by controlling the aircraft in pitch by varying the lift of the front surface rather than the rear surface, i.e., by using a canard layout. A pitching divergence can then be checked, or a stall recovery made by reducing the lift of the canard surface, which is always possible, rather than by increasing the lift of a tail surface, which may be impossible.

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“…4, such an equation can be derived from thermodynamics. From de= T ds-p dv (2) with entropy s-and specific volume v we get, expressing the total differential dsin terms of differentials in rand v,…”

Section: Thermodynamicsmentioning

confidence: 99%

“…The local adiabatic exponent is defined for a differential change in state by 12 v ( dp \ p a= --(--) = -a 2 p \ dv / s p…”

Section: * and A From The Equations Of Statementioning

confidence: 99%

Theoretical Investigations of Real Gas Effects in Cryogenic Wind Tunnels

Wagner

Schmidt

1978

AIAA Journal

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Real gas effects in cryogenic nitrogen flows have been calculated using the Beattie-Bridgeman equation of state. The investigations include Prandtl-Meyer expansions; oblique shocks, transonic small perturbation theory, transonic flow past a NACA 0012 aerofoil, and shock-wave/boundary-layer interaction. The last two cases mentioned have been treated with the aid of finite volume techniques. The results show som noticeable deviations from the behavior of an ideal gas, not only at cryogenic conditions but also at normal temperatures and high pressures. Within the operating range of cryogenic wind tunnels the deviations remain very small; only the friction coefficient exhibits a considerable amount of systematic variation.

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Cryogenic nitrogen as a transonic wind-tunnel test gas

Cited by 11 publications

References 0 publications

The Influence of Gas Models on Numerical Simulations of Cryogenic Flow

The Influence of Gas Models on Numerical Simulations of Cryogenic Flow

Simulation of flat-plate turbulent boundary layers in cryogenic tunnels

Theoretical Investigations of Real Gas Effects in Cryogenic Wind Tunnels

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