Flame Extensions Under Ceilings

Sammanfattning: In this Master thesis project the factors affecting flame extension under flat and curved ceilings have been investigated. An experimental campaign was carried out in Lund University’s Fire Lab using a propane gas burner and heptane pool fire in different positions and heat release rates within the setups. A flame recognition Python script was developed to identify the flame length in the videos taken for each test. The flame length data was then compared with flame length models found in the literature review. Results show that the flame extension under the curved ceiling were larger than under the flat ceiling: this is because the curved geometry affects the flow’s buoyancy component, enhancing it and resulting in larger flames. Furthermore, the reduced entrainment of the side wall position makes unburnt fuel travel further under the ceiling extending the flame more. Differences in the flow characteristics also impacts the flame length: momentum driven flows such as that produced by the propane burner have a longer flame extension compared to the buoyancy driven flow of a pool fire. The greatest differences between the test data and the models found in literature result form the neglection of the flow’s buoyancy component. Different test setups, fuels and test configurations can also be the cause of the found discrepancies. Adaptations of the relations put forward by the literature for the test results were therefore found in this work. Further study into different fuel types and burner positions would provide more information regarding the fire’s behaviour beneath ceilings and keep structures and people inside them safe.