Drag Coefficient Measurement of Spheres in a Vertical Shock Tube and Numerical Simulation

Rodriguez, G.; Grandeboeuf, P.; Khelifi, Mohamed; Haas, J. F.

doi:10.1007/978-3-642-78835-2_6

Cited by 12 publications

(6 citation statements)

References 3 publications

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“…Although it is not clear which correlation performs better, it is evident that compressibility, or Mach number of the induced flow, correlates well with the increased drag coefficients. The current results are therefore supportive of the argument that the increased drag coefficients of spheres having low acceleration parameters reported in previous shock tube studies [21,[28][29][30][31] can be attributed to compressibility rather than flow unsteadiness. Other factors may play a role as well in some experiments, such as freestream turbulence levels or particle roughness or asymmetry.…”

Section: Discussion Of Single-particle Dragsupporting

confidence: 91%

“…When applied to unsteady flows, apparent discrepancies arise. A number of studies have measured higher values of C D for an unsteady flow than would be predicted by a standard drag model [21,[28][29][30][31]. In such cases, unsteadiness refers to the acceleration of a particle at rest when subjected to the flow behind a shock wave, or the deceleration of a particle in a ballistic test.…”

Section: Historical Backgroundmentioning

confidence: 99%

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Experimental characterization of energetic material dynamics for multiphase blast simulation.

Beresh¹,

Wagner²,

Kearney³

et al. 2011

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Currently there is a substantial lack of data for interactions of shock waves with particle fields having volume fractions residing between the dilute and granular regimes, which creates one of the largest sources of uncertainty in the simulation of energetic material detonation. To close this gap, a novel Multiphase Shock Tube has been constructed to drive a planar shock wave into a dense gassolid field of particles. A nearly spatially isotropic field of particles is generated in the test section by a gravity-fed method that results in a spanwise curtain of spherical 100-micron particles having a volume fraction of about 19%. Interactions with incident shock Mach numbers of 1.66, 1.92, and 2.02 were achieved. High-speed schlieren imaging simultaneous with high-frequency wall pressure measurements are used to reveal the complex wave structure associated with the interaction. Following incident shock impingement, transmitted and reflected shocks are observed, which lead to differences in particle drag across the streamwise dimension of the curtain. Shortly thereafter, the particle field begins to propagate downstream and spread. For all three Mach numbers tested, the energy and momentum fluxes in the induced flow far downstream are reduced about 30-40% by the presence of the particle field. X-Ray diagnostics have been developed to penetrate the opacity of the flow, revealing the concentrations throughout the particle field as it expands and spreads downstream with time. Furthermore, an X-Ray particle tracking velocimetry diagnostic has been demonstrated to be feasible for this flow, which can be used to follow the trajectory of tracer particles seeded into the curtain. Additional experiments on single spherical particles accelerated behind an incident shock 4 wave have shown that elevated particle drag coefficients can be attributed to increased compressibility rather than flow unsteadiness, clarifying confusing results from the historical database of shock tube experiments. The development of the Multiphase Shock Tube and associated diagnostic capabilities offers experimental capability to a previously inaccessible regime, which can provide unprecedented data concerning particle dynamics of dense gas-solid flows. 5

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Section: Discussion Of Single-particle Dragsupporting

confidence: 91%

Section: Historical Backgroundmentioning

confidence: 99%

Experimental characterization of energetic material dynamics for multiphase blast simulation.

Beresh¹,

Wagner²,

Kearney³

et al. 2011

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“…where µ is the viscosity of the gas, which was evaluated by using Sutherland's formula. The recent experimental results of Igra and Takayama (1993) and of Rodriguez et al (1995) as well as the standard drag curves proposed by Morsi and Alexander (1972) for Re < 50 000, by White (1986) for Re > 50 000 and by Henderson (1976) are also shown in figure 5.…”

Section: Drag Coefficient Measurementmentioning

confidence: 78%

Shock tube study of particles' motion behind a planar shock wave

Suzuki

Sakamura

Igra

et al. 2005

Meas. Sci. Technol.

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In order to shed light on the initial mechanism of dust entrainment behind a moving shock wave, the particles' motion behind a planar shock wave was investigated using horizontally placed shock tubes and a direct photographic technique synchronized with the shock wave motion. The drag coefficient measurement of an accelerating spherical particle (0.3–5.57 mm in diameter) was performed. The obtained drag coefficients were found to be higher than those from the standard drag curve. On average, the difference was about 20% for a relative Reynolds number from 103 and 105. The initial motion of a particle just lifted-up from the wall was also examined using the other shock tube. The results indicated that the velocity and speed of rotation of particles were strongly affected by the floor conditions. It was also found that the particle's initial rotation does not play a major role in the particle rise.

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“…This in turn allows the present investigations to cover both subsonic and supersonic post-shock flow cases. As was done in previous experiments (Igra & Takayama 1993;Rodriguez et al 1993;Suzuki et al 1999), here too the sphere drag coefficient, C D , was deduced from its trajectory. To obtain an accurate reconstruction of the investigated sphere's trajectory, the windows in the presently used test section had a field of view of 80!300 mm (300 mm in the flow direction).…”

Section: Experimental Facilitiesmentioning

confidence: 95%

“…Later, Rodriguez et al (1993) investigated both the steady and unsteady drag coefficients of a sphere initially free-falling in a vertical shock tube, using a rapid camera shadowgraph technique. Their work investigated the drag coefficient of a sphere, but, in each experiment, 20-30 particles were dropped down the vertical shock tube in order to ensure that at least one of them would be present in the field of view during its interaction with the incident shock wave.…”

Section: Introductionmentioning

confidence: 99%

Drag coefficient of a sphere in a non-stationary flow: new results

et al. 2007

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The drag coefficient of a sphere placed in a non-stationary flow is studied experimentally over a wide range of Reynolds numbers in subsonic and supersonic flows. Experiments were conducted in a shock tube where the investigated balls were suspended, far from all the tube walls, on a very thin wire taken from a spider web. During each experiment, many shadowgraph photos were taken to enable an accurate construction of the sphere's trajectory. Based on the sphere's trajectory, its drag coefficient was evaluated. It was shown that a large difference exists between the sphere drag coefficient in steady and non-steady flows. In the investigated range of Reynolds numbers, the difference exceeds 50%. Based on the obtained results, a correlation for the non-stationary drag coefficient of a sphere is given. This correlation can be used safely in simulating two-phase flows composed of small spherical particles immersed in a gaseous medium.

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Drag Coefficient Measurement of Spheres in a Vertical Shock Tube and Numerical Simulation

Cited by 12 publications

References 3 publications

Experimental characterization of energetic material dynamics for multiphase blast simulation.

Experimental characterization of energetic material dynamics for multiphase blast simulation.

Shock tube study of particles' motion behind a planar shock wave

Drag coefficient of a sphere in a non-stationary flow: new results

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