https://doi.org/10.1140/epjs/s11734-025-02042-8
Regular Article
An experimental study on flame spread and heat transfer along thin hollow cylindrical fuels in microgravity
Department of Aerospace Engineering and National Center for Combustion Research and Development (NCCRD), Indian Institute of Technology Madras, Chennai, India
a
vipinsrivastava2010@gmail.com
Received:
2
June
2025
Accepted:
21
October
2025
Published online:
28
October
2025
Hollow cylindrical geometries represent critical and commonly encountered geometry in spacecraft systems appearing in tubes, conduits, wire housing, and structural elements. Understanding flame spread over hollow cylindrical fuels is highly relevant for the application of space fire safety. This work presents experimental study on opposed flow flame spread over thin hollow cylindrical cellulosic fuel of diameters varying from 10 to 49 mm in microgravity environment. To understand the effect of flow on flame spread, experiments are conducted in low convective opposed flow conditions ranging from 10 to 30 cm/s for different hollow cylindrical fuel diameters at oxygen concentration of 21% and 1 atm pressure. In the microgravity environment, the flame length and the flame spread rate are seen to increase with increase in hollow cylindrical fuel diameter over the flow range studied here. The flame spread rate exhibited a non-monotonic trend with flow speed, for flow of large diameter whereas a monotonic increasing trend is noted for small diameters. A simplified analysis is carried out to arrive at an expression for flame spread rate over thin hollow cylindrical fuels. The analysis shows that the radiation exchange from the hot char to the inner surface of hollow virgin fuel (solid to solid radiation) and overall equivalence ratio dictates flame spread rate trend with fuel diameter. This study addresses the existing knowledge gap on flame propagation along hollow cylindrical surfaces, where strong flame interaction and oxygen starvation are competing each other inside cylinder. This advances the fundamental understanding of flame spread in complex geometries. These insights are particularly valuable for identifying atypical fire behaviors in space environments.
Copyright comment Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
© The Author(s), under exclusive licence to EDP Sciences, Springer-Verlag GmbH Germany, part of Springer Nature 2025
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
