Smoldering is an important, but often overlooked aspect of fire safety.
Smolder detection is difficult due to the fact that the reaction temperatures
are relatively low and occur within the porous material. For this reason, the
smolder reaction can progress for long periods of time, undetected, and then
undergo a sudden transition to flaming.
The overall project objective is to increase the fundamental understanding and the predictability of smoldering combustion, which will aid in the prevention and control of smolder originated fires, under normal- and micro- gravity conditions. The specific objective is to determine the smolder characteristics of a polymeric, porous, combustible material, in quiescent and convective oxidizing environments, at normal- and micro- gravity.
The project objective is to perform smolder experiments on both ground- and space- based facilities, whereupon theoretical models of the process can be developed. The experiments are conducted using polyurethane foam as fuel and mixtures of oxygen/nitrogen as oxidizer. Thermocouples measure the temperature at several locations of the sample; and from the resulting temperature histories, smolder propagation velocity and smolder reaction temperature, as functions of the oxidizer flow velocity and oxygen concentration, can be obtained. The experimental results will serve to verify and to improve the theoretical models of smoldering combustion. Additional experiments study the conditions and mechanisms involved in the potential transition from smoldering to flaming.
Smoldering is important both as a fundamental combustion problem (i.e., the propagation of a heterogeneous, non-flaming, surface combustion reaction through a porous combustible material) and as a fire safety problem (i.e., the production of toxic compounds and the potential initiation of a fire by way of a transition to flaming). Microgravity introduces additional questions about the transport of mass and heat to and from the reaction zone, which must be resolved so that smolder behavior can be better predicted in a space-based environment.
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| Microgravity Smoldering | Forward Flow Smoldering | Opposed Flow Smoldering | 2-D Smolder and Transition to Flaming | Ultrasound Imaging and Tomography |
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