Transition from smoldering to flaming fire in short cotton samples with asymmetrical boundary conditions

The transition from smoldering to flaming fire in cotton has been investigated for two different boundary conditions: (a) open boundaries and (b) a lightweight concrete block covering one side of the sample. In the experiments, cotton was exposed from below to an electrically heated hotplate. The cotton sample was 0.15m×0.15m×0.15m, with density between 20 and 100kg/m3.