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Experimental analysis of the breakage of a liquid bridge under microgravity conditions

Experimental analysis of the breakage of a liquid bridge under microgravity conditions. I. Martínez , J.M . Perales Universidad Politécnica de Madrid, Spain COSPAR 2010 Thursday , 22 nd July 2010. Spacelab-D2, Experiment “ STACO ”, Run 2. Experiment description.

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Experimental analysis of the breakage of a liquid bridge under microgravity conditions

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  1. Experimental analysis of the breakage of a liquid bridge under microgravity conditions I. Martínez, J.M. Perales Universidad Politécnica de Madrid, Spain COSPAR 2010 Thursday, 22ndJuly2010

  2. Spacelab-D2, Experiment“STACO”, Run 2

  3. Experimentdescription • ExperimentperformedonboardSpacelab D-2 (1993) with AFPM. • Fluid used: siliconeoil of n=10 cSt, r=920 kg/m3, s=0.020 N/m. • Supports: two 30 mm in diametercircular coaxial disks made of aluminiumblack-anodized, with a 30º dove-tailcut back. • Nominal shape: cylindricalliquidcolumnwithL=85 mm length. • Diffuse white background illumination (9·8 leds). • Ref.: • Martínez, I., Perales, J.M., Meseguer, J., Stability of long liquid columns (SL-D2-FPM-STACO), in Scientific Results of the German Spacelab Mission D-2, Ed. Sahm, P.R., Keller, M.H., Schiewe, B, WPF, pp. 220-231, 1995. • Martínez, I., http://webserver.dmt.upm.es/~isidoro/lc1/SL/ST2_118_13_30_41stretch_xvid.avi

  4. Automated image edging

  5. Stabilitydiagramforunloadedliquid bridgesStretchingevolution at constantvolumefrom A to B

  6. Experimental values (length, volume, stability)

  7. Non-dimensionalization

  8. Columnshapesand theirstability (nondimensional) • Equilibriumshapeswithv<<1 (linearized) and L~π • Dynamicshapes (firsteigenfunction) • Stabilitylimit

  9. Fittingtheliquidshapewith 1-, 2-, 3-terms

  10. Evolution of thefirstsine term (a) and cosineterm (b)

  11. Neckingdynamics

  12. Stabilitymargin

  13. Linear inviscid stable and unstable response

  14. Diverging amplitude (amphora-type deformation)

  15. Conclusions • Non-linear dynamic simulation of the breaking process has yield a perfect matching with experimental results, which linear theories did not achieve. • Many small details in the experimental results are still unexplained (e.g. the lack of decay in the small free oscillations; g-jitter?). • Automated image analysis has progressed a lot, but small problems remain (full image analysis helps a lot, but details of the discs are not visible). • Digital imaging nowadays would solve many of the old video problems. • Actual liquid column in space appear always oscillating (microgravity): • Around an equilibrium shape that is unexpected (a residual load shows up) • With a small but non-decaying amplitude (0.3 mm peak-to-peak) • With a frequency very close to the first natural frequency (axial, and lateral). • Useful experimental time in space is always very scarce (e.g. a couple of minutes in half an hour, here). • Unique experiments may have some unknown boundary conditions (repetition is a must, but these experiments have not been reproduced yet).

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