Es erkennt hier eine sprudelnde Quelle. Wir auch. - ULV Leoben ...
Es erkennt hier eine sprudelnde Quelle. Wir auch. - ULV Leoben ...
Es erkennt hier eine sprudelnde Quelle. Wir auch. - ULV Leoben ...
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PIV during the NH 4 Cl solidification<br />
For a better understanding of the metals solidification process we applied Particle<br />
Image Velocimetry technique during the solidification of a transparent alloy<br />
30wt.% NH 4 Cl-70wt.% H 2 O.<br />
Very complex phenomena occur during the solidification<br />
of metals. A closer look at the solid and liquid movement<br />
and eventually interaction in between them can<br />
lead to a better understanding. Solid is represented by<br />
the equiaxed grains and liquid by the melt liquid. Using<br />
the PIV (Particle Image Velocimetry) technique with two<br />
CCD cameras mounted in parallel, we could observe<br />
simultaneously solid and liquid movement. The velocity<br />
of equiaxed grains and the flow velocity could be determined<br />
and therefore the relative velocity. The height of<br />
the columnar zone can also be measured.<br />
Mihaela Stefan Kharicha<br />
Lehrstuhl für Modellierung und Simulation<br />
metallurgischer Prozesse<br />
an der MUL seit: 2003<br />
Email: mihaela.kharicha@unileoben.ac.at<br />
www.smmp.at.hm<br />
Zur Person:<br />
Ph.D. student in Metallurgy- Combinend optical measurement<br />
techniques applied to convection processes during equiaxed<br />
solidification<br />
During the solidification of a 29,52 wt.%<br />
NH 4 Cl different stages can be observed.<br />
Within approx. 6 min after the commencement<br />
of the cooling process a symmetric<br />
convection pattern establishes. After 12 min a<br />
second stage could be observed, whereby the<br />
solute buoyancy adds/opposes to the thermal<br />
buoyancy. Small vortices start to appear,<br />
firstly along the walls and latterly spreading<br />
out in the cell. The process continues with<br />
the falling down of the crystals, being strong<br />
enough to involve the flow with it. At the last<br />
stage a new phenomenon was seen, a meandering<br />
flow movement (see pic. below).<br />
1st stage symetric convection<br />
flow<br />
3rd stage down flow<br />
Forschungspartner:<br />
2nd stage with small vortices<br />
4th stage meandering flow<br />
Forschungsschwerpunkte:<br />
Solidification, Data base for the CFD simulation,<br />
Flow characteristics, equiaxed grains velocity<br />
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