Pyrolysis Smoke Generated Under Low-Gravity Conditions
Jiann C. Yang, Thomas G. Cleary, George W. Mulholland, D L. Urban, Gary A. Ruff, Zeng-guang Yuan, Marit Meyer, Victoria Bryg
A series of smoke experiments were carried out in the Microgravity Science Glovebox on the International Space Station (ISS) Facility to assess the impact of low-gravity conditions on the size distribution and structure of the smoke aerosol. This information will be used in the design of better fire detection for spacecraft. The smokes were generated by heating five different materials (all polymers) commonly used in space vehicles. They were characterized by the measurement of the zeroth, first, and third moments of the size distribution. This study focuses on the effects of flow and heating temperature for both normal and low-gravity conditions on the pyrolysis rate, the smoke plume structure, the smoke yield, the size distribution, and particle structure. Low-gravity conditions allowed a unique opportunity to study the smoke plume for zero external flow without the complication of buoyancy. The diameter of average mass for the smoke increased on average by a factor of 1.7 and the morphology of the smoke changed from agglomerate with flow to spherical at no flow for one material. The no flow case is an important scenario in spacecraft where smoke could be generated by the overheating of electronic components in confined spaces. The low-gravity conditions allowed the study of coagulation without the complication of particle losses due to gravity. From electron microcopy of samples returned to earth, it was found that pyrolysis smoke can form an agglomerate shape as well as a spherical shape, which had previously been the assumed shape. The relationship between the properties of the pyrolysis vapors and the smoke structure is discussed.
, Cleary, T.
, Mulholland, G.
, Urban, D.
, Ruff, G.
, Yuan, Z.
, Meyer, M.
and Bryg, V.
Pyrolysis Smoke Generated Under Low-Gravity Conditions, Aerosol Science and Technology, [online], https://doi.org/10.1080/02786826.2015.1025125
(Accessed February 23, 2024)