?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.relation=http%3A%2F%2Fmiis.maths.ox.ac.uk%2Fmiis%2F560%2F&rft.title=Efficient+design+of+tall+tapered+feeders&rft.creator=McGuinness%2C+M.J.&rft.creator=Roberts%2C+A.J.&rft.subject=Materials&rft.description=Toowoomba+Foundry+is+seeking+help+with+the+design+of+tall+tapered+feeders%2C+which+supply+extra+molten+iron+to+poured+castings+as+they+cool.+There+is+a+problem+with+the+reliability+of+the+feeders%2C+particularly+for+thicker+castings+of+the+newer+spheroidal+graphite+irons.+An+effective+feeder+remains+molten+until+the+casting+has+set.+The+setting+of+the+melt+in+the+feeder+is+delayed+by+making+it+large+enough+to+retain+its+heat+for+longer+than+the+casting%2C+and+by+placing+it+close+to+the+thermal+centre+of+the+casting.+So+a+larger+feeder+is+more+reliable.+But+any+metal+remaining+in+the+feeder+is+recycled%2C+and+has+an+associated+energy+cost.+If+a+feeder+is+too+small%2C+it+will+set+too+soon%2C+and+the+casting+will+have+unwanted+holes+in+it+that+may+require+the+entire+casting+to+be+recycled.+Thus+there+is+a+tension+between+making+the+feeder+smaller+so+as+to+minimise+recycled+metal%2C+and+having+the+feeder+large+enough+that+the+casting+is+good.%0D%0A%0D%0AExisting+design+methods+use+purely+conductive+models+of+heat+transport.+We+investigate+the+relevance+of+convection+in+the+cooling+feeder%2C+and+set+up+a+boundary-layer+model+of+flow+driven+by+density+differences.+We+find+that+convection+is+a+significant+factor+in+the+design+of+a+feeder%2C+effectively+maintaining+constant+temperature+across+it.+The+height+of+the+feeder+is+important+mainly+in+providing+the+driving+force+for+this+flow.&rft.date=2001&rft.type=Study+Group+Report&rft.type=NonPeerReviewed&rft.format=application%2Fpdf&rft.language=en&rft.identifier=http%3A%2F%2Fmiis.maths.ox.ac.uk%2Fmiis%2F560%2F1%2FEfficient-design-of-tall-tapered-feeders.pdf&rft.identifier=++McGuinness%2C+M.J.+and+Roberts%2C+A.J.++(2001)+Efficient+design+of+tall+tapered+feeders.++%5BStudy+Group+Report%5D+++++