Numerical investigation of air stability in space capsule under low gravity conditions

To obtain reasonable air distribution in space capsule, the indoor air stabilities under two basic gravity conditions - weightlessness and lunar gravity conditions - are studied in this paper. The influences of the indoor air stability on the characteristics of pollutant transport (CO2) are discussed, by means of computational fluid dynamics (CFD) method under three different air stability conditions: stable condition, neutral condition and unstable condition. Two preliminary three-dimensional physical models were established and used to compare the influence of different arrangements of outlets and positions of pollutant source on the contaminant distributions. The results show that the air stability under the weightless conditions has no impact on the pollutant diffusion. However, the air stability under low gravity conditions significantly affects the pollutant spread and diffusion in the space capsule. Under lunar gravity conditions, the pollutant under unstable conditions has an obvious tendency of deviating from the mainstream direction and approaching the two flanks. On the contrary, the pollutant under stable condition moves faster in the mainstream direction and arrives at outlets more easily. It is possible that the air stability exists under low gravity conditions and affects the characteristics of pollutant transport.