An “ideal equivalent gas method” for the study of shock waves in supersonic real gas flows

Vallerani, E.

doi:10.1007/bf02133438

Cited by 5 publications

(2 citation statements)

References 2 publications

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“…The air domain is widely considered an ideal gas for the study of several aerodynamic problems, satisfying the ideal gas law (32). As such, the material type MAT_NULL is used to define the evolution of the density of air, while the pressure is defined by a linear-polynomial equation of state, given by…”

Section: Materials Modellingmentioning

confidence: 99%

Layout considerations on compound survival shelters for blast mitigation: A finite-element approach

Caçoilo,

Mourão,

Lecompte

et al. 2023

International Journal of Protective Structures

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The safety of both military personnel and equipment in unstable regions has for a long time been a major issue and concern. Protective shelters with multiple configurations have been widely used to meet safety requirements. Since military compounds are subjected to different types of threats, such as the detonation of improvised explosive devices (IED), a good understanding of the response of such shielding structures to blast waves is critical. A three-dimensional finite element (FE) model of a corner-entry ISO 20 ft container HESCO-Bastion survival shelter is developed, validated and tested under the external detonation of explosive charges. The FE model is validated against experimental data and used to investigate the protective performance of the shelter by considering several design-related parameters, such as charge location, roof extension, interior corridor dimensions and the effect of venting and its location. Results are discussed in terms of peak overpressure and maximum impulse at discrete locations around the container, and it is found that the shelter is the least efficient in mitigating the blast load propagation when the explosive material is at an angle of 45° to the entrance. Also, while the protective roof at the entrance plays a significant role in protecting the container from air-borne threats, it is observed that it contributes to higher pressure and impulse data within the shelter, for detonations at ground level, with impulse amplifications as high as 94% when fully covering the entrance area. Contrarily, varying the distance between the container and the HESCO-Bastions is found to have minimal impact on the impulse, while naturally decreasing the peak pressure for increasing distances. Venting (through openings) can lead to up to 95% reduction in the peak pressure, whilst not affecting the impulse.

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Section: Materials Modellingmentioning

confidence: 99%

Layout considerations on compound survival shelters for blast mitigation: A finite-element approach

Caçoilo,

Mourão,

Lecompte

et al. 2023

International Journal of Protective Structures

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“…This deviation can potentially be explained by the fact that air is here modelled by a perfect gas law, where γ remains constant at 1.4, and not a real gas one. Some literature works, as the ones of Vallerani in 1969 [39], give the evolution of the specific heat ratio over a large M range. According to their results, it appears that at M = 4.26 and the corresponding γ is rather 1.38.…”

Section: The Bow-shock Positionmentioning

confidence: 99%

Numerical investigation of the interactions between a low-hypersonic shock wave and a water droplet: VOF and DI methods comparison

Tymen¹,

Hebert²,

Rullier³

et al. 2020

Int. J. CMEM

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In this paper, we present the hydrodynamic mechanisms which occur between a low-hypersonic shock wave and a millimetric water droplet. To do so, two numerical models, based respectively on the Volume of Fluid (VOF) and Diffuse Interfaces (DI) approaches, are developed. The goal is to compare the results obtained with the models in order to evaluate which is the most accurate to describe the evolution of the physical phenomena. The studied Mach number and initial droplet diameter are 4.25 and 1.135 mm, respectively. Each model allows the compressible Euler equations to be solved in a 2D-axisymmetric configuration. The evolution of both air and liquid phases is modelled by a stiffened gas equation of state. For qualitative validation, the numerical results are compared to experimental data recently presented in the literature. In this work, the authors used a shock tube test facility and a shadowgraph visualization technique to observe the phenomenology over a long time. Their investigation shows that the droplet deformation, detached bow shock and recompression waves are well captured by the two models until a Rayleigh dimensionless time of 1.5. Beyond this critical time, and up to 3, some differences appear between the two numerical approaches, especially on the droplet deformation. Globally, the droplet deformation is better described with the VOF model, while the DI model appears to be more accurate when it comes to the evaluation of the position of the bow shock. In the discussion section, some ideas are proposed to improve the models.

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Theoretical Modeling of Aero-Heating Under Nonequilibrium Real Gas Effects

Wang

2014

Theoretical Modelling of Aeroheating on Sharpened Noses Under Rarefied Gas Effects and Nonequilibrium Real Gas Effects

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An “ideal equivalent gas method” for the study of shock waves in supersonic real gas flows

Cited by 5 publications

References 2 publications

Layout considerations on compound survival shelters for blast mitigation: A finite-element approach

Layout considerations on compound survival shelters for blast mitigation: A finite-element approach

Numerical investigation of the interactions between a low-hypersonic shock wave and a water droplet: VOF and DI methods comparison

Theoretical Modeling of Aero-Heating Under Nonequilibrium Real Gas Effects

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