of flutes
In the course of this study, it was found that magnitude of the air
gap between cast iron and carbon has a significant impact on the
predicted voltage drop, as it controls the resulting contact quality
at the carbon to cast iron interface.
A finite element demonstration model of a simplified anode
assembly was built using the in-house code FESh++ to study the
impact of the anode stub hole design on the anode voltage drop.
The coupled thermal-electrical-mechanical problem was solved
iteratively, taking into account the behaviour of the cast iron to
carbon cast iron interface.
An alternative 16 flutes stub hole was compared to a base case
design with 6 flutes. Despite the increased nominal surface area
and the increased cast iron mass, the resulting anode voltage drop
was found to increase slightly due to the decrease of contact
quality. Minimisation of the stub-to-carbon voltage drop is
therefore a balancing act between the real contact area and the
resulting electrical contact resistance.
The accurate prediction of the contact quality hinges on the
accurate prediction of the ambient temperature air gap between
cast iron and carbon. Although it can be calibrated on in situ
measurements, development of an analytical or numerical
prediction methodology would make an interesting research area.
From the work presented here, it can be seen that a numerical
model is an invaluable tool to gain insights into the complex
interactions of steel, cast iron and carbon in an anode stub hole.
Once validated on experimental measurements, it can be used in
the optimisation of the stub hole geometry with respect to anode
voltage drop and cast iron volume.
We thank Hugues Fortin from REGAL and Lowy Gunnewiek
from Hatch for their support and for the useful discussions and
comments. A part of the research presented in this paper was
financed by the Fonds québécois de la recherche sur la nature et
les technologies by the intermediary of the Aluminium Research
Centre REGAL and Natural Sciences and Engineering Research
Council of Canada. We thank also, Daniel Marceau from
Aluminium Research Centre REGAL, for the access to the high
performance computing facilities of UQAC.
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