An Experiment to Determine Interfacial Heat Transfer
Coefficients During Active Cooling of Investment Castings
The University of Alabama
Department of Mechanical Engineering
August 2002
Abstract of Thesis
This thesis details the development
of an experiment to obtain the temperature data necessary to estimate the
interfacial heat transfer coefficients in actively cooled aluminum alloy
investment castings.The process of
active cooling is a method of controlling the solidification of nonferrous
alloys that experience “mushy” freezing so that micropores and hot tears may be
reduced.Interfacial heat transfer
coefficients are computed from the data obtained in the experiments by solving
the Inverse Heat Conduction Problem.
The experiments are performed for
alloys A356 and A206.Tests are
performed while the castings cool in ambient air, during immersion into a
fluidized bed of sand, and during immersion into a liquid metal bath.Experiments are conducted for different mold
immersion rates for the fluidized bed and liquid metal bath cases.Tests are performed at various bath
temperatures for the liquid metal bath experiments.
The temperature histories obtained from the
experiments for all of these cases are presented.Some sample interfacial heat transfer
coefficient results are also included.
Acknowledgments
This
research was conducted under the guidance of my doctoral advisor, Dr. Keith
Woodbury. Many challenges surfaced during this work, and Dr. Woodbury and Dr. Tom Piwonka patiently helped me find solutions to all of the problems, few of which were trivial. On a weekly basis I was welcomed by Mike Payne the folks at North American Precision Casting of Mississippi into their steel casting facility to make the investment shell molds for my research. A lot of people at the University of Alabama helped out as well. Bob Fanning, foundry technician extraordinaire, was a huge help in about a thousand different ways. Richard Wear, Zach Nuckols, Chad Woodard, Destin Sandlin, and Ty were all undergraduates who contributed to the project.
