Modeling Characterization of Smoke Particle Transport and Fate in Lunar Gravity
CLAIRE FORTENBERRY, David Urban, Gary Ruff,
NASA Glenn Research Center Abstract Number: 521
Working Group: Combustion
AbstractSpacecraft fires present one of the most dangerous scenarios threatening crew safety for future lunar and deep space missions. Optimal spacecraft fire detector placement strategies are challenged by transport phenomena unique to reduced gravity environments. Studies of spacecraft fire detection conducted to date have focused on microgravity systems, but, as NASA plans to return to the Moon, more research is needed to evaluate optimal detector placement in lunar gravity. Chiefly, improved knowledge of plume transport in lunar gravity is needed; unlike in microgravity, some buoyant plume flow is expected, though transport timescales remain unclear. Furthermore, previous research has demonstrated that spacecraft life support system properties, particularly high cabin filtration rates, lengthen times to alarm. The optimal detector placement in a lunar habitat will involve a balance between these two factors.
We present computational results on smoke particle transport in lunar gravity. This model combines turbulent flow, heat transport, and particle transport from a simulated fuel overheating (pre-flame) scenario under varied maximum temperature and fuel configuration conditions. Particle velocities are mapped in lunar gravity and compared to results from micro- and terrestrial gravity to evaluate timescales for buoyant transport. Additionally, forced air flow is introduced to mimic a hypothetical scenario with cabin air supplies on the ceiling and returns on the floor. Results suggest that in lunar gravity, smoke particles travel upward at velocities similar in magnitude to average air velocities on the ISS. This upward flow may enable strategic placement of smoke detectors on ceilings of future lunar spacecraft cabins, depending on the cabin ventilation velocity, air filtering characteristics, and habitat design.