Ground Based Thermal Scale Modeling Of A Space Station Cabin And Experimental Research

How to simulate experimentally the flow and heat transfer under microgravity on the ground is important, which has not been completely solved so far. The objective of this paper is to study the problems about the ground modeling experiment on the ventilation and heat transfer in the cabin of the space station under microgravity. A set of experimental system for the ground modeling were built up based on the theoretical analyses of the effects of gravity on the flow and heat transfer in the cabin. It was discovered by analyses and experiments that if keeping Reynolds number unchanged, the effect of gravity can be minimized remarkably by decreasing the size of the model. It was proved experimentally that the effects of gravity on the flow pattern, the distributions of velocity, temperature, Nuesselt number can be neglected when the thermal scale ratio of model was suitable. It was found through experiment that the radiation between cabin inner walls must be considered for uniform heat flux condition, that is, the wall heat flux in the model must be modified in order to keep flow and heat transfer similarity between the model and prototype. Meanwhile, the measured Nuesselt number were larger than the values of numerical prediction because the air flow in the cabin was belong to the non-typical turbulent flow in the range of Reynolds number studied.A set of ground model systems having multi-functions were established for the research on the flow, heat transfer and condensation in the cabin. Three means of ventilation in the cabin — uniform gas inlet, vertical slot gas inlet and 45° slot gas inlet were investigated experimentally. The velocity, temperature, relative moisture and convective heat transfer coefficients in the cabin were measured. These configurations of ventilation were evaluated according to the homogeneity of temperature and velocity, the requirement of comfort and the performance of heat transfer in the cabin.The condensation on the inner surface of the cabin was studied in this paper. The similarity between the model and the prototype in the zone apt to condensation was discussed through numerical simulation, and some ways to guarantee the similarity of ventilation and heat transfer were advanced. Three kinds of measures preventing inner surfaces from dewing can be taken in cabin areas if necessary.