Exploring the Validity of the Spalart-Allmaras Turbulence Model for Hypersonic Flows

Paciorri, Renato; Dieudonne, W.; Degrez, Gérard; Charbonnier, Jean-Marc; Deconinck, H.

doi:10.2514/2.3307

Cited by 30 publications

(11 citation statements)

References 2 publications

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“…This property is important when, as in the present cases, geometrical configurations include more than a single wall. In addition, the Spalart-Allmaras model has shown good performance in the computation both of compressible flows [13][14][15] and of complex three-dimensional flows [16,17].…”

Section: Flow Modeling and Numerical Methodsmentioning

confidence: 98%

Performance Analysis of an Infinite Array Linear Clusterd Plug Nozzle

Geron¹,

Paciorri

Nasuti

et al. 2007

Journal of Propulsion and Power

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Section: Flow Modeling and Numerical Methodsmentioning

confidence: 98%

Performance Analysis of an Infinite Array Linear Clusterd Plug Nozzle

Geron¹,

Paciorri

Nasuti

et al. 2007

Journal of Propulsion and Power

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“…Paciorri [71] In conclusion, we observe that CFD has become one of the preferred simulation tools in thermal-hydraulics studies for portions of nuclear systems. The nuclear industry relies mostly on commercial CFD-codes, but these codes exhibit a few drawbacks: They were not aimed at modeling large pressure and temperature variations which lead inevitably to major property variations.…”

Section: Discussion On the Spalart-allmaras Modelmentioning

confidence: 99%

Ultrahigh Specific Impulse Nuclear Thermal Propulsion

Charmeau¹,

Cunningham²,

Anghaie³

2009

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PREFACEResearch on nuclear thermal propulsion systems (NTP) have been in forefront of the space nuclear power and propulsion due to their design simplicity and their promise for providing very high thrust at reasonably high specific impulse. During NERVA-ROVER program in late 1950's till early 1970's, the United Sates developed and ground tested about 18 NTP systems without ever deploying them into space. The NERVA-ROVER program included development and testing of NTP systems with very high thrust (~ 250,000 lb f ) and relatively high specific impulse (~ 850 s). High thrust to weight ratio in NTP systems is an indicator of high acceleration that could be achieved with these systems. The specific impulse in the lowest mass propellant, hydrogen, is a function of square root of absolute temperature in the NTP thrust chamber. Therefore, optimizing design performance of NTP systems would require achieving the highest possible hydrogen temperature at reasonably high thrust to weight ratio. High hydrogen exit temperature produces high specific impulse that is a direct measure of propellant usage efficiency.After the cancellation of the US NERVA-ROVER program in early 1970's, the Former Soviet Union continued with the US effort and made improvement in fuel design that enabled design and ground testing of an NTP systems (1984) at temperatures and specific impulses well above what had been achieved during the NERVA-ROVER program (hydrogen exit temperature ~ 3,000 K and specific impulse ~ 1,000 s). The renewed interest in the space nuclear power and propulsion is the main motivation for the proposed research that is intended to develop reactor design and NTP systems for achieving the highest possible specific impulseResearch conducted in support of the development of a new nuclear powered thermal rocket propulsion system is proposed to provide variable thrust in the range of 1,000 to 10,000 lb f of thrust at 1000-1500 seconds of ideal specific impulse (Isp) by heating relatively lowpressure hydrogen propellant to average temperatures ranging from 3000 K to 3250 K. The reactor for the proposed NTR concept is fueled with a uranium tetra-carbide compound that is optimized for resisting atomic and molecular hydrogen at temperatures above 3000 K. Uranium tetra-and tri-carbide fuels feature the highest corrosion resistance properties at elevated temperatures in hydrogen environment. The congruent melting of tetra-and tri-carbides is not overly sensitive to carbon content, as it's the case for uranium bi-carbides such as uraniumzirconium and uranium-niobium carbides. This is a key property of these fuels that would enable their applications for operation at temperatures above 3000 K. The fuel candidate for this concept is the solid solution of uranium-zirconium-niobium-titanium carbide, (U, Zr, Nb, Ti)C.Compare to uranium tri-carbides that have previously been considered for application in NTP systems, the proposed uranium tetra-carbide features higher stability in dissociated hydrogen and more favorable neutronic characteristics...

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“…The Spalart-Allmaras (S-A) model is an empirically derived one-equation turbulence model which relates the Reynolds stress to the mean strain rate through turbulent viscosity29, ν , which is a flow variable whose distribution is given by1…”

Section: Methodsmentioning

confidence: 99%

Ozone uptake during inspiratory flow in a model of the larynx, trachea and primary bronchial bifurcation

Padaki

Ultman

Borhan

2009

Chemical Engineering Science

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Three-dimensional simulations of the transport and uptake of a reactive gas such as O 3 were compared between an idealized model of the larynx, trachea, and first bifurcation and a second "control" model in which the larynx was replaced by an equivalent, cylindrical, tube segment. The Navier-Stokes equations, Spalart-Allmaras turbulence equation, and convection-diffusion equation were implemented at conditions reflecting inhalation into an adult human lung. Simulation results were used to analyze axial velocity, turbulent viscosity, local fractional uptake, and regional uptake. Axial velocity data revealed a strong laryngeal jet with a reattachment point in the proximal trachea. Turbulent viscosity data indicated that jet turbulence occurred only at high Reynolds numbers and was attenuated by the first bifurcation. Local fractional uptake data affirmed hotspots previously reported at the first carina, and suggested additional hotspots at the glottal constriction and jet reattachment point in the proximal trachea. These laryngeal effects strongly depended on inlet Reynolds number, with maximal effects (approaching 15%) occurring at maximal inlet flow rates. While the increase in the regional uptake caused by the larynx subsided by the end of the model, the effect of the larynx on cumulative uptake persisted further downstream. These results suggest that with prolonged exposure to a reactive gas, entire regions of the larynx and proximal trachea could show signs of tissue injury.

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Exploring the Validity of the Spalart-Allmaras Turbulence Model for Hypersonic Flows

Cited by 30 publications

References 2 publications

Performance Analysis of an Infinite Array Linear Clusterd Plug Nozzle

Performance Analysis of an Infinite Array Linear Clusterd Plug Nozzle

Ultrahigh Specific Impulse Nuclear Thermal Propulsion

Ozone uptake during inspiratory flow in a model of the larynx, trachea and primary bronchial bifurcation

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