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Correlation of Normal Gravity Mixed Convection Blowoff Limits with Microgravity Forced Flow Blowoff LimitsThe axisymmetric rod geometry in upward axial stagnation flow provides a simple way to measure normal gravity blowoff limits to compare with microgravity Burning and Suppression of Solids - II (BASS-II) results recently obtained aboard the International Space Station. This testing utilized the same BASS-II concurrent rod geometry, but with the addition of normal gravity buoyant flow. Cast polymethylmethacrylate (PMMA) rods of diameters ranging from 0.635 cm to 3.81 cm were burned at oxygen concentrations ranging from 14 to 18% by volume. The forced flow velocity where blowoff occurred was determined for each rod size and oxygen concentration. These blowoff limits compare favorably with the BASS-II results when the buoyant stretch is included and the flow is corrected by considering the blockage factor of the fuel. From these results, the normal gravity blowoff boundary for this axisymmetric rod geometry is determined to be linear, with oxygen concentration directly proportional to flow speed. We describe a new normal gravity 'upward flame spread test' method which extrapolates the linear blowoff boundary to the zero stretch limit in order to resolve microgravity flammability limits-something current methods cannot do. This new test method can improve spacecraft fire safety for future exploration missions by providing a tractable way to obtain good estimates of material flammability in low gravity.
Document ID
20160012691
Acquisition Source
Glenn Research Center
Document Type
Conference Paper
Authors
Marcum, Jeremy W.
(Akron Univ. Akron, OH, United States)
Olson, Sandra L.
(NASA Glenn Research Center Cleveland, OH United States)
Ferkul, Paul V.
(Universities Space Research Association Cleveland, OH, United States)
Date Acquired
October 27, 2016
Publication Date
May 15, 2016
Subject Category
Space Transportation And Safety
Fluid Mechanics And Thermodynamics
Report/Patent Number
GRC-E-DAA-TN30478
Meeting Information
Meeting: 2016 Spring Technical Meeting of the Central States Section of The Combustion Institute
Location: Knoxville, TN
Country: United States
Start Date: May 15, 2016
End Date: May 17, 2016
Sponsors: Combustion Inst.
Funding Number(s)
WBS: WBS 904211.04.02.20.16
CONTRACT_GRANT: NNC13BA10B
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
microgravity
blowoff
flammability
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