Intangible archaeologies of hot air Sri Lanka Samanalawewa Archaeological survey and excavation over a number of years revealed a major industry 80 sites of the 7 th and 11 th centuries ID: 560301
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Slide1
MONSOON STEEL
Intangible archaeologies of hot airSlide2Slide3Slide4Slide5
Sri LankaSlide6
SamanalawewaSlide7
Archaeological survey and excavation over a number of years revealed a major industry (80+ sites) of the 7
th
and 11th centuries AD, based on a wind-powered linear furnace designSlide8
Reconstructed furnace from archaeological evidenceSlide9
Experimental
smelts in 1994 and 2007Slide10
mid-smelt - 1994
towards end of smelt - 1994Slide11Slide12
Flow of air and flame up the front
wall - 2007Slide13
Smelting at nightSlide14
Smelting at night gave clues to the complex air flows
through and over the furnaceSlide15
Breaking apart the
furnace and slag
to retrieve themetal ‘blooms’Slide16
Metal products of smelts
Analysis showed this to be
high quality high-carbon steelSlide17
At the time the
wind-powered furnaces of Sri Lanka were
producinghigh-carbon steel the Early Islamicwriter al-Kindi praised Sarandibisteel as one of the most desirablefor
sword-making
High-carbon
steels and Damascus swordsSlide18
Data visualisation
Data sets
wind direction and velocity for region and macro-environment wind direction and velocity for site-level environment wind velocities at furnace level during experimental smelting
furnace temperatures at
tuyere
(air inlet) and charcoal bed during smelting
ore and charcoal fuel charging weights and rates
tap slag running timesSlide19
The results of the
field experiments were published in
Nature (379, 1996)Tangible and Intangible Archaeology
Collected hard evidence – slag waste, metals, furnace remains, experimental experience, images, data
How do we ‘capture’ the fugitive but critical evidence of natural and managed air flow and combustion?
How do we visualise it and importantly
use it as a tool for further research?Slide20
First interpretation of air flow through furnace based on observations and recorded data (furnace cross-section)Slide21
Further
research using computational
fluid dynamics (CFD) at Exeter refinedthe initial
analysis. Paper with Gavin Tabor published in
Journal of Archaeological ScienceSlide22Slide23Slide24Slide25Slide26
Arrangement of instruments to measure
temperatureSlide27Slide28
Computation of all temperature readings across furnace through duration of smelt (Matt Baker)Slide29
Further applications: other furnace technologies
Sri Lanka: small, bellows-driven shaft furnace last used in early 20
th
century
Well-recorded example with archaeological, ethnographic and documentary recordsSlide30
Furnace shape and size reconstructed from excavation and written accounts
Experimental example built and run in Exeter by engineering students (MJ Baker, R De
Salis, D Dawson)CFD analysis of airflows including quasi-sinusoidal flow modelSlide31Slide32Slide33
THANK YOU
POTENTIAL
With good datasets from archaeological excavations and experimental smelting
Visualise and model CFD data
Potential as a tool for study and interpretation of ancient
pyrotechnologies
Potential to make visible intangible archaeology
Potential for interdisciplinary knowledge transfer and public dissemination
Potential to engage with creative industry to present science and technology