Shock-tube experiments on Richtmyer–Meshkov instability growth using an enlarged double-bump perturbation

This article reports on the latest experiments in the series of Richtmyer–Meshkov instability (RMI) shock-tube experiments. Previous work described a double-bump experiment that evidenced some degree of unrepeatability. The present work features an enlarged perturbation introduced to improve repeatability. In common with the previous work, the experiments were conducted at shock Mach number 1.26 (70 kPa overpressure), using the Atomic Weapons Establishment 200 × 100 mm shock tube with a three-zone test cell arrangement of air/sulphur hexafluoride/air. The sulphur hexafluoride gas (SF6) was chosen for its high density (5.1 relative to air) providing an Atwood number of 0.67. Gas separation was by means of microfilm membranes, supported by fine wire meshes. A double-bump perturbation of two-dimensional geometry was superimposed on the downstream membrane representing a 0.6% addition to the dense gas volume. Visualization of the turbulent gas mixing was by laser sheet illumination of the seeded SF6gas using a copper vapor laser pulsing at 12.5 kHz. Mie scattered light was recorded using a 35-mm rotating drum camera to capture a sequence of 50 images per experiment. Sample experimental results shown alongside corresponding three-dimensional hydrocode calculations highlight the problems in both analysis and comparison caused by multiple scattering arising from the necessary use of a high seeding concentration. Included is a demonstration of the effectiveness of introducing into the hydrocode a Monte Carlo-based simulation of the multiple scattering process. The results so derived yield greatly improved qualitative agreement with the experimental images. Quantitative analysis took the form of deriving relative intensity data from line-outs through experimental images and their code equivalents. A comparison revealed substantial agreement on major features.

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Mix experiments using a two-dimensional convergent shock-tube

Laser and Particle Beams ◽

10.1017/s0263034603213185 ◽

2003 ◽

Vol 21 (3) ◽

pp. 403-409 ◽

Cited By ~ 8

Author(s):

D.A. HOLDER ◽

A.V. SMITH ◽

C.J. BARTON ◽

D.L. YOUNGS

Keyword(s):

Shock Tube ◽

Turbulent Mixing ◽

Three Dimensional ◽

Gas Mixture ◽

Mixing Process ◽

Dense Gas ◽

Atomic Weapons ◽

Air Void ◽

Good Agreement ◽

Three Dimensional Simulations

This article reports the first Richtmyer–Meshkov instability experiments using an improved version of the Atomic Weapons Establishment convergent shock tube. These investigate the shock-induced turbulent mixing across the interfaces of an air/dense gas/air region. Multipoint ignition of a detonatable gas mixture produces a cylindrically convergent shock that travels into a test cell containing the dense gas region. The mixing process is imaged with shadowgraphy. Sample results are presented from an unperturbed experiment and one with a notch perturbation imposed on one of the dense gas interfaces. The unperturbed experiment shows the mixing across the dense gas boundaries and the motion of the bulk dense gas region. Imposition of the notch perturbation produces a mushroom-shaped air void penetrating the dense gas region. Three-dimensional simulations performed using the AWE TURMOIL3D code are presented and compared with the sample experimental results. A very good agreement is demonstrated. Conducting these first turbulent mixing experiments has highlighted a number of areas for future development of the convergent shock-tube facility; these are also presented.

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IMAGING OF IMPINGING JET BREAKUP AND ATOMIZATION PROCESSES USING COPPER-VAPOR-LASER-SHEET-ILLUMINATED PHOTOGRAPHY

International Journal of Energetic Materials and Chemical Propulsion ◽

10.1615/intjenergeticmaterialschemprop.v3.i1-6.560 ◽

1994 ◽

Vol 3 (1-6) ◽

pp. 552-568

Author(s):

M. C. Kline ◽

R. D. Woodward ◽

R. L. Burch ◽

F. B. Cheung ◽

Kenneth K. Kuo

Keyword(s):

Laser Sheet ◽

Impinging Jet ◽

Copper Vapor Laser ◽

Vapor Laser ◽

Copper Vapor ◽

Jet Breakup

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The Peak Overpressure Field Resulting From Shocks Emerging From Circular Shock Tubes

Journal of Fluids Engineering ◽

10.1115/1.4002183 ◽

2010 ◽

Vol 132 (8) ◽

Cited By ~ 6

Author(s):

A. J. Newman ◽

J. C. Mollendorf

Keyword(s):

Shock Tube ◽

Horizontal Plane ◽

Three Dimensional ◽

Polar Angle ◽

Field Measurements ◽

Initial Development ◽

Theoretical Predictions ◽

Mach Numbers ◽

Tube Exit ◽

Semi Empirical

A simple semi-empirical model for predicting the peak overpressure field that results when a shock emerges from a circular shock tube is presented and validated. By assuming that the shape of the expanding shock remains geometrically similar after an initial development period, an equation that describes the peak overpressure field in the horizontal plane containing the shock tube’s centerline was developed. The accuracy of this equation was evaluated experimentally by collecting peak overpressure field measurements along radials from the shock tube exit at 0 deg, 45 deg, and 90 deg over a range of shock Mach numbers from 1.15 to 1.45. It was found that the equation became more accurate at higher Mach numbers with percent differences between experimental measurements and theoretical predictions ranging from 1.1% to 3.6% over the range of Mach numbers considered. (1) Shocks do propagate in a geometrically similar manner after some initial development length over the range of Mach numbers considered here. (2) The model developed here gives reasonable predictions for the overpressure field from a shock emerging from a circular shock tube. (3) Shocks are expected to be completely symmetric with respect to the shock tube’s centerline, and hence, a three dimensional overpressure field may be predicted by the model developed here. (4) While there is a range of polar angle at which the shock shape may be described as being spherical with respect to the shock tube’s exit, this range does not encompass the entirety of the half space in front of the shock tube, and the model developed here is needed to accurately describe the entire peak overpressure field.

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Three dimensional HiLo-based structured illumination for a digital scanned laser sheet microscopy (DSLM) in thick tissue imaging

Optics in the Life Sciences ◽

10.1364/boda.2013.bt1a.3 ◽

2013 ◽

Author(s):

Dipanjan Bhattacharya ◽

Vijay Raj Singh ◽

Chen Zhi ◽

Peter T. C. So ◽

Paul Matsudaira ◽

...

Keyword(s):

Laser Sheet ◽

Three Dimensional ◽

Tissue Imaging ◽

Structured Illumination

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A Non-Intrusive Experimental Technique for Constructing Poincaré Maps in 3D Chaotically Advected Flows

10.1115/imece2001/fed-24932 ◽

2001 ◽

Author(s):

Fotis Sotiropoulos ◽

Igor Mezić ◽

Donald R. Webster

Keyword(s):

Light Intensity ◽

Experimental Technique ◽

Vortex Breakdown ◽

Laser Sheet ◽

Three Dimensional ◽

Chaotic Advection ◽

Time Averaging ◽

Poincaré Maps ◽

Poincare Maps ◽

The Rich

Abstract We propose and develop the theoretical framework for a new experimental technique for constructing Poincaré maps in three-dimensional flows exhibiting chaotic advection. The technique is non-intrusive and, thus, simple to implement. Planar laser-induced fluorescence (LIF) is employed to collect a sufficiently long sequence of instantaneous light intensity fields on the plane of section of the Poincaré map (defined by the laser sheet). The chains of unmixed (regular) islands in the flow are visualized by time-averaging the instantaneous images and plotting iso-contours of the resulting mean light intensity field. A rigorous theoretical justification for this technique is derived using concepts from ergodic theory. We demonstrate the capabilities of the method by applying it to visualize the rich Lagrangian dynamics within steady vortex breakdown bubbles in a closed cylinder with a rotating bottom. The experimental results are shown to be in excellent agreement with numerical simulations.

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The Laser Sheet as a Quantitative Diagnostic Tool in Shock Tube Experiments

Shock Waves @ Marseille IV ◽

10.1007/978-3-642-79532-9_48 ◽

1995 ◽

pp. 287-292 ◽

Cited By ~ 1

Author(s):

D. Landeg ◽

M. Philpott ◽

I. Smith ◽

A. Smith ◽

N. Cowperthwaite ◽

...

Keyword(s):

Shock Tube ◽

Diagnostic Tool ◽

Laser Sheet

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Numerical and Experimental Study of Flow Field between the Main Hull and Demi-Hull of a Trimaran

Journal of Marine Science and Engineering ◽

10.3390/jmse8120975 ◽

2020 ◽

Vol 8 (12) ◽

pp. 975

Author(s):

Cong Sun ◽

Chunyu Guo ◽

Chao Wang ◽

Lianzhou Wang ◽

Jianfeng Lin

Keyword(s):

Flow Field ◽

High Speed ◽

Light Transmission ◽

Transmission Rate ◽

Laser Sheet ◽

Three Dimensional ◽

Wake Flow ◽

Navier Stokes ◽

Unsteady Wake ◽

Real Flow

The interactions between the main hull and demi-hull of trimarans have been arousing increasing attention, and detailed circumferential flow fields greatly influence trimaran research. In this research, the unsteady wake flow field of a trimaran was obtained by Reynolds-Averaged Navier-Stokes (RANS) equations on the basis of the viscous flow principles with consideration of the heaving and pitching of the trimaran. Then, we designed an experimental method based on particle-image velocimetry (PIV) and obtained a detailed flow field between the main hull and demi-hull of the trimaran. A trimaran model with one demi-hull made of polycarbonate material with 90% light transmission rate and a refractive index 1.58 (close to that of water 1.33) was manufactured as the experiment sample. Using polycarbonate material, the laser-sheet light-source transmission and high-speed camera recording problems were effectively rectified. Moreover, a nonstandard calibration was added into the PIV flow field measurement system. Then, we established an inverse three-dimensional (3D) distortion coordinate system and obtained the corresponding coordinates by using optics calculations. Further, the PIV system spatial mapping was corrected, and the real flow field was obtained. The simulation results were highly consistent with the experimental data, which showed the methods established in this study provided a strong reference for obtaining the detailed flow field information between the main hull and demi-hull of trimarans.

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Blast load simulation using conical shock tube systems

International Journal of Protective Structures ◽

10.1177/2041419619858098 ◽

2019 ◽

Vol 11 (2) ◽

pp. 135-158 ◽

Cited By ~ 1

Author(s):

Ahmed Ismail ◽

Mohamed Ezzeldin ◽

Wael El-Dakhakhni ◽

Michael Tait

Keyword(s):

Shock Tube ◽

Three Dimensional ◽

Design Parameters ◽

Civil Infrastructure ◽

Two Dimensional ◽

Blast Loads ◽

Dimensional Model ◽

Tube System ◽

Three Dimensional Model ◽

Conical Shock

With the increased frequency of accidental and deliberate explosions, evaluating the response of civil infrastructure systems to blast loading has been attracting the interests of the research and regulatory communities. However, with the high cost and complex safety and logistical issues associated with field explosives testing, North American blast-resistant construction standards (e.g. ASCE 59-11 and CSA S850-12) recommend the use of shock tubes to simulate blast loads and evaluate relevant structural response. This study first aims at developing a simplified two-dimensional axisymmetric shock tube model, implemented in ANSYS Fluent, a computational fluid dynamics software, and then validating the model using the classical Sod’s shock tube problem solution, as well as available shock tube experimental test results. Subsequently, the developed model is compared to a more complex three-dimensional model and the results show that there is negligible difference between the two models for axisymmetric shock tube performance simulation; however, the three-dimensional model is necessary to simulate non-axisymmetric shock tubes. Following the model validation, extensive analyses are performed to evaluate the influences of shock tube design parameters (e.g. the driver section pressure and length and the expansion section length) on blast wave characteristics to facilitate a shock tube design that would generate shock waves similar to those experienced by civil infrastructure components under blast loads. The results show that the peak reflected pressure increases as the driver pressure increases, while a decrease in the expansion length increases the peak reflected pressure. In addition, the positive phase duration increases as both the driver length and expansion length are increased. Finally, the developed two-dimensional axisymmetric model is used to optimize the dimensions of a physical large-scale conical shock tube system constructed for civil infrastructure component blast response evaluation applications. The capabilities of such shock tube system are further investigated by correlating its design parameters to a range of explosion threats identified by different hemispherical TNT charge weight and distance scenarios.

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Flow Measurements in a Model Burner—Part 2

Journal of Fluids Engineering ◽

10.1115/1.2910140 ◽

1993 ◽

Vol 115 (2) ◽

pp. 309-316

Author(s):

D. F. G. Dura˜o ◽

M. V. Heitor ◽

A. L. N. Moreira

Keyword(s):

Laser Doppler Velocimetry ◽

Swirling Flow ◽

Laser Sheet ◽

Three Dimensional ◽

Swirling Flows ◽

Dimensional Structure ◽

Mixing Efficiency ◽

Flow Measurements ◽

Circular Jets ◽

Turbulence Production

The isothermal swirling flow in the vicinity of a model oxy-fuel industrial burner is analyzed with laser-Doppler velocimetry together with laser-sheet visualization. The burner consists of a central axisymmetric swirling jet surrounded by sixteen circular jets, simulating the injection of oxygen in practical burners. The results extend those obtained for non-swirling flows, and presented in Part 1 of this paper, to the analysis of the dependence of the mixing efficiency of the burner assembly upon the swirl motion of the central jet and have the necessary detail to allow to assess the accuracy of calculation procedures of the flow in industrial burners. It is shown that swirl attenuates the three-dimensional structure typical of multijet flows in such a way that turbulence production and transport in the near burner zone are dominated by swirl-induced processes.

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