Shock Tube Richtmyer-Meshkov Experiments: Inverse Chevron and Half Height

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Allan Nelson
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1 Shock Tube Richtmyer-Meshkov Experiments: Inverse Chevron and Half Height Presented by: David Holder D A Holder, C J Barton and D L Youngs British Crown Copyright 24/MOD Published with the permission of the controller of Her Britannic Majesty s Stationery Office. Job No/ 1

2 Contents Inverse Chevron Description of experimental configuration Experimental results Comparison with TURMOIL 3D LES results Sample analysis Half Height Description of experimental configuration Experimental results Comparison with TURMOIL 3D LES results Sample analysis Conclusions Future work Job No/ 2

3 Shock Tube Maximum Compression chamber pressure 138kPa (2psi) Maximum Incident shock overpressure in air 234kPa (34psi) Shock Mach number 1.73 Job No/ 3

4 Inverse Chevron Perturbation 7kPa Shock Air Seeded SF 6 Air Seeded SF 6 region constrained with microfilm membranes supported on wire meshes. 15mm 1mm 2mm Atwood Number.67 Meshes on both interfaces are made from horizontal and vertical 25µm wires with 4mm spacing. the total flow blockage is 1.25% Job No/ 4

5 Inverse Chevron Perturbation (cont.) The chevron perturbations were conceived as a progression from the work of Meshkov et al. and a Test Problem from the IWPCTM meetings. Wall Wall Wall Wall Wall Previous Work Present Work The chevrons take advantage of a larger shock tube to eliminate any possible constraining effect of one wall and also to investigate boundary layer effects. The inverse chevron experiment complements the previous work. Wall Job No/ 5

6 Test Cell Set-up ICCD or Inverse Chevron Job No/ 6

7 Sample Results ms 2.2ms.5ms 2.7ms 1.3ms 3.3ms 1.9ms 4.ms Job No/ 7

8 Video of Results Job No/ 8

9 TURMOIL3D Calculations 1D Lagrangian Region 3D Region Shocked Air 1.72 bar Air 1 bar SF 6 1 bar Air 1 bar End Wall 2cm 15cm 15cm 2cm Zoning used in 3D region : 4 x 32 x 16 Semi-Lagrangian calculation : x-direction mesh moves with the mean fluid velocity. Random initial perturbation at air/sf6 interfaces: Wavelengths =.5 to 5cm R.M.S. amplitude =.1cm Job No/ 9

10 Experimental and Code Comparison ( - 1.9ms) ms.5ms Experimental Images 1.3ms Code + Scattering Correction 1.9ms Job No/ 1

11 Experimental and Code Comparison (2.2-4.ms) 2.2ms 2.7ms Experimental Images 3.3ms Code + Scattering Correction 4.ms Job No/ 11

3 35 5 1 15 2 25 3 35 6 Middle 25 Middle 14 Middle 5

12 Lineouts at 4.ms for Code and Experiment LST 343 ICCD CODE LST 343 FILM 6 5 Top Bottom 25 2 Top Bottom 12 1 Top Bottom Middle 25 Middle 14 Middle Job No/ 12

13 Test Cell for Half Height Job No/ 13

14 Test Cell for Half Height (2) 15 mm 2 mm 11mm Seeded SF 6 1mm Drain Fired without plug - minimal effect on the mixing process Job No/ 14

15 Sample Experimental Results (1) ms.3 ms.1 ms.4 ms.2 ms Air Shock.4 ms Schematic SF 6 Shock Job No/ 15

16 Sample Experimental Results (2) 1. ms 2. ms 3. ms 4. ms Job No/ 16

17 Video of Results Job No/ 17

18 TURMOIL 3D LES 1D Lagrangian Region 3D Region Shocked Air 1.72 Bar Air 1 Bar SF 6 1 Bar Air 1 Bar 15cm 15cm 2cm Semi-Lagrangian Calculation: x-direction mesh moves with the mean fluid velocity Zoning in 3D Region 64 x 32 x 2 (note more zones to accommodate gas region moving further) Random initial perturbation at air/sf6 interfaces: Wavelengths =.5 to 5cm, R.M.S. amplitude =.1cm Job No/ 18

19 Experiment Experimental and Code Comparison.9ms Code + Scattering.1ms.21ms.2ms.29ms.3ms.37ms.4ms Job No/ 19

20 Experimental and Code Comparison (2) Experiment.9ms Code + Scattering.1ms.21ms.2ms.29ms.3ms.37ms.4ms Job No/ 2

2 15 1 1 5 5 5 1 15 2 25 3 35 5 1 15 2 25 3 35 4 35

21 Image Analysis.4ms Experiment Code 4 35 Top 4 35 Top Bottom 4 35 Bottom Job No/ 21

2 1 1 5 1 15 2 25 3 35 6 Bottom 5 5 1 15 2 25

22 Image Analysis 4.ms Experiment Code 6 Top 6 Top Bottom Bottom Job No/ 22

23 Conclusions Conducted inverse chevron experiments to complement the chevron experiments reported previously Achieved good qualitative agreement with code results Again highlighted the usefulness of the Monte Carlo post processing to add multiple scattering to the code results Performed lineout analysis to illustrate agreement with code, however this is only semi-quantitative due to the presence of multiple scattering Conducted Half Height experiments which superimpose a Kelvin-Helmholtz shear instability on a Richtmyer Meshkov experiment Results show a good visual comparison between experiment and code Achieved good agreement in shock positions in the early time images Semi-quantitative analysis has been performed with good overall results although this has demonstrated problems with the Monte-Carlo multiple scattering code which need to be addressed Job No/ 23

24 Future Work Further analysis is required of these results to enable more comparison with the TURMOIL 3D results. Especially to solve the problem with the multiple scattering code. Two new intensified CCD cameras have been implemented into the recording system allowing full digital recording of experiments Fluorescent vapour seeding to eliminate multiple scattering will be implemented in the shock tube shortly Further use of the new Convergent Shock Tube facility to extend these studies into 2D at higher Mach numbers Job No/ 24

Shock-Induced Instability Experiments on Gas Interfaces Featuring a Single Discrete Perturbation

Shock-Induced Instability Experiments on Gas Interfaces Featuring a Single Discrete Perturbation Originally published in Proceedings of the Fifth International Workshop on Compressible Turbulent Mixing, ed. R. Young, J. Glimm & B. Boston. ISBN 9810229100, World Scientific (1996). Reproduced with the