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Finite Element Modeling of Thermal Regulation in Extra Vehicular Activity
Biswas, Rohit; France, Emma; Paradkar, Mihir; Woods, Zach
Astronauts perspire heavily during the strenuous exercise of Extravehicular Activity (EVA), and previous literature has expressed concern that this may negatively impact the ability of the LCVG to maintain thermal comfort. However, thorough testing of EVA suits on Earth is nearly impossible due to difficulty in replicating the harsh conditions of space. This project strived to alleviate the necessity of physical simulation with a computer-based model using the software package COMSOL. The model was designed to simulate the fluid and heat transfer dynamics in EVA suits. In particular, we examined the suit’s Liquid Cooling and Ventilation Garment (LCVG), an inner layer of fabric and coolant tubing that regulates astronaut body temperature. We modeled leakage of perspiration into this fabric layer, creating space- and time-dependent heat flow properties in the system. We used both a 2D simplified geometry and a realistic humanoid 3D geometry to balance physical accuracy requirements with available computational power. We show that skin temperature in anatomical locations of heavy perspiration varies more than in drier locations. We also show that the skin surface temperature is maintained at a comfortable level by the LCVG even during swings in levels of external radiative heating. Finally, we show that a varying metabolic rate corresponds to variations in skin temperature with time. Skin surface temperature and its control have implications for both astronaut comfort and LCVG efficiency. We have shown that it is possible to study the effects of various parameters on skin temperature using a simple finite element model. This enables safer and more comfortable suit design without the undue time, cost, and complexity of full physical testing. We have also shown that the effects of perspiration can be consequential, and are worth exploration in further research.
Finite Element Modeling; Thermal Regulation; Extra Vehicular Activity