Abstract
A CFD(Computational Fluid Dynamics) model has been developed using the commercial CFD package FLUENT for the thermal convection inside air filled cylindrical DACON sensor, where the onboard time dependent gravitational micro acceleration has been considered. Time dependent, curve fitted gravitational accelera-tion in x- and y-axes from published data have been incorporated in FLUENT through a User Defined Function (UDF), developed in C which includes space craft rotation. At the sensor plane the two-dimensional flow has also been visualized. A good agreement is between simu-lation and published experimental data. Last but not the least, for checking its response to suffi-ciently strong perturbations in an orbital flight, physical and numerical experiments are carried out where an astronaut swung the sensor in hands along the y axis with amplitude of 10cm and a frequency of 0.2 Hz. A good qualitative validation has been achieved between CFD and actual experimental results.
Highlights
Microgravity indicates low gravity, where the mean gravitational acceleration is in the range of 10–1 - 10–5 m/s2
As the sensitivity of the DACON is relatively low, for checking its response to sufficiently strong perturbations in an orbital flight, an experiment is carried out where an astronaut swung the sensor in hands along the y axis(according to Figure 1) with an amplitude of 10 - 25 cm and a frequency of 0.18 - 0.2 Hz [6]
The CFD simulation of DACON sensor has been doflow is basically based on thermal creep
Summary
Microgravity indicates low gravity, where the mean gravitational acceleration is in the range of 10–1 - 10–5 m/s2. DACON convection sensor, shown, is an air-filled cylindrical cavity of strictly controlled boundary conditions for quick calculation of temperature field under real space flight conditions (under on-board micro-acceleration). With that confidence, stronger g jitter perturbation for an astronaut swung in a Mir-station experiment has been evaluated using CFD and compared with the actual experimental results. This approach (use of previously reported gravitational data) is more appropriate CFD modeling in this particular case. CFD simulation provides more insight of the natural convection physics under actual g-jitter which had not been even captured through the physical experiment
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