Simulations of gas cloud expansion using a multi-temperature gas dynamics model

Dogra, Virendra K.; Erlandson, R. E.; Swaminathan, P. K.; Nance, Robert P.

doi:10.1063/1.1407560

Cited by 5 publications

(3 citation statements)

References 10 publications

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“…The predictions by the code of pre-flight model with experiment data show that a single-temperature (T) model is not physically correct due to insufficient number of collisions among the gas species to reach vibrational-translational equilibrium [9]. Therefore, some researchers [10,11] developed a multi-T model in order to include rarefaction effects. However, the radiance level from the vibrationaltranslational equilibrium can be predicted better by the single-T model than multi-T model.…”

Section: Introductionmentioning

confidence: 99%

Design of Hypervelocity Flow Generator (HFG) and Its Diagnostics

D¹,

H²

2022

J Aerosp Eng Mech

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Ground facility for hypersonic research is a key element for successful development of aerodynamically proven hypervelocity vehicles. Design concept and diagnostics of hypervelocity flow generator (HFG) were made as a test platform for hypersonic/hypervelocity spacecraft models at NASA Langley Research Center. The HFG is a hypersonic flow field generator using optically heated gas which was blown into an 80-m 3 large vacuum chamber. The vacuum chamber is kept at a stable vacuum pressure with a combination of three large vacuum pumps, while the HFG is in the test mode. The HFG provides relatively a small test section with approximately a 20 cm window. This facility was designed to generate 2.45 km/sec of flow speed, and possibly to generate a continuous flow with the nozzle and vacuum system. The window at test section provides a direct observation of shock wave around a model in order to measure temperature, pressure, and density profile within the shock layer. One of the key test goals under this project was to understand why the emission spectra from the standing shockwave plasma predicted by Lora-Loran codes are significantly different from the measured emission spectra from the Flight Investigation Reentry Environment (FIRE II) Flight. The correct estimate of thermal loading on the leading edge of hypersonic vehicles greatly improves the aerodynamic design, the material selection for vehicle, and the cooling requirement and can be obtained by the precise modeling of emission spectra from shockwave plasma. However, the estimation of thermal loading is not an easy task due to complex non-equilibrium radiative process within high temperature shock layers that still falls into a category of cold plasma. Direct flight experiments are the most desirable, but not a cost-effective approach. Analysis by computational fluid dynamics (CFD) offers many test flexibilities. However, the CFD codes must be fully tested and validated with experimental data before the codes are effectively used for practical design. The large discrepancies between experiments and codes are appeared in hypersonic/hypervelocity flow regime at high altitude of 60-90 km. This HFG facility offers some important parameters for CFD code validation, such as collision cross-sections, relaxation times, reaction rate coefficients and transportation coefficients. The HFG test facility is based on the ejection flow of high temperature gas heated over to 3500 °K through a nozzle. The tungsten gas chamber of HFG is heated up to a desired temperature by a 60-kW optical power beam source. This system consists of an optical power source, a thermal chamber, an expansion nozzle, a test section, and an 80 m 3 vacuum tanks. Total 60 kW optical input power is obtained from the 150 kW Vortek arc lamp system. This optical beam is focused to heat the gas chamber within which a flow media is heated. The maximum achievable temperature of the flow medium reached approximately 3500K or even higher but is limited by the melting point of the chamber material used. The exhaus...

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Section: Introductionmentioning

confidence: 99%

Design of Hypervelocity Flow Generator (HFG) and Its Diagnostics

D¹,

H²

2022

J Aerosp Eng Mech

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“…Candler et al [4] developed a multi-temperature equation set and compared numerical solutions for the normal shock wave problem with DSMC results. Dogra et al [5] presented calculations using a multi-temperature model for unsteady blast-type problems. Baganoff [6] has presented a numerical method for Maxwell's moment equations for the normal shock problem.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Translational Anisotropy in Rarefied Flows Using Kinetic Approaches

Wadsworth¹,

Gimelshein²,

Gimelshein³

et al. 2008

AIP Conference Proceedings

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“…Time accurate numerical simulations of a rapidly expanding high temperature gas cloud are performed using both a multi-temperature gas dynamics model [3][4] and the DSMC method 2 . The influence of the source radius and source and ambient density are evaluated.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulations of Gas Cloud Expansion in Rarefied Environment

Dogra¹,

Wadsworth²

2004

Self Cite

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Abstract. Time accurate numerical simulations of a high temperature source cloud of gas expanding into an ambient atmosphere are performed using a multiple temperature gas model and the direct simulation Monte Carlo (DSMC) method. The multi-temperature approach uses continuum conservation equations derived from the Boltzmann equation via first-order Chapman-Enskog expansion and zero-order non-isotropic velocity distribution function. These equations are solved numerically using a kinetic flux splitting method for inviscid fluxes and a central difference scheme for the viscous fluxes in a time accurate manner. The DSMC technique is a well-established particle approach for rarefied flows. The source and ambient densities and temperatures are varied to establish the range of applicability and relative accuracy of the two methods. For most of the source and the ambient parameter considered, the two methods give similar predictions of the basic flowfield evolution, and of the degree of translational non-equilibrium that arises.

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Simulations of gas cloud expansion using a multi-temperature gas dynamics model

Cited by 5 publications

References 10 publications

Design of Hypervelocity Flow Generator (HFG) and Its Diagnostics

Design of Hypervelocity Flow Generator (HFG) and Its Diagnostics

Assessment of Translational Anisotropy in Rarefied Flows Using Kinetic Approaches

Numerical Simulations of Gas Cloud Expansion in Rarefied Environment

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