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Low-Temperature Oxidation Reactions and Cool Flames at Earth and Reduced GravityNon-isothermal studies of cool flames and low temperature oxidation reactions in unstirred closed vessels are complicated by the perturbing effects of natural convection at earth gravity. Buoyant convection due to self-heating during the course of slow reaction produces spatio-temporal variations in the thermal and thus specie concentration fields due to the Arrhenius temperature dependence of the reaction rates. Such complexities have never been quantitatively modeled and were the primary impetus for the development of CSTR's (continuously stirred tank reactors) 30 years ago. While CSTR's have been widely adopted since they offer the advantage of spatial uniformity in temperature and concentration, all gradients are necessarily destroyed along with any structure that may otherwise develop. Microgravity offers a unique environment where buoyant convection can be effectively minimized and the need for stirring eliminated. Moreover, eliminating buoyancy and the need for stirring eliminates complications associated with the induced hydrodynamic field whose influence on heat transport and hot spot formation, hence explosion limits, is not fully realized. The objective of this research is to quantitatively determine and understand the fundamental mechanisms that control the onset and evolution of low temperature reactions and cool flames in both static and flow reactors. Microgravity experiments will be conducted to obtain benchmark data on the structure (spatio-temporal temperature, concentration, flow fields), the dynamics of the chemical fronts, and the ignition diagrams (pressure vs. temperature). Ground-based experiments will be conducted to ascertain the role of buoyancy. Numerical simulations including detailed kinetics will be conducted and compared to experiment.
Document ID
19990054006
Acquisition Source
Glenn Research Center
Document Type
Conference Paper
Authors
Pearlman, Howard
(University of Southern California Los Angeles, CA United States)
Date Acquired
August 19, 2013
Publication Date
May 1, 1999
Publication Information
Publication: Fifth International Microgravity Combustion Workshop
Subject Category
Inorganic And Physical Chemistry
Funding Number(s)
CONTRACT_GRANT: NCC3-501
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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