Open Access

ARTICLE

A Comparative Study of G-jitter Effect on Thermal Diffusion aboard the International Space Station

by Y. Yan¹, K. Jules², M. Z. Saghir¹

1 Ryerson University, Department of Mechanical and Indus-trial Engineering, 350 Victoria Street, Toronto, ON, M5B2K3, Canada
2 NASA Johnson Space Center, Mail Code OZ4, 2101 NASA Parkway, Houston, Texas, USA

Fluid Dynamics & Materials Processing 2007, 3(3), 231-246. https://doi.org/10.3970/fdmp.2007.003.231

Abstract

Fluid science research including thermal diffusion in fluids benefits from the quiescent low-gravity environment provided by the International Space Station (ISS). However, residual gravities (or g-jitters) aboard the ISS impact the overall environment in which experiments are being performed. The impact of these residual gravities needs to be assessed to ensure that they are appropriately accounted for when results are being reported for experiments performed onboard the ISS. In this paper we study the thermal diffusion process in a ternary mixture of n-butane, dodecane and methane. Measured data from the Space Acceleration Measurement System (SAMS) acceleration system onboard the ISS and related influence on fluid flow are compared with the ideal zero-gravity simulation to illustrate the effect of reduced gravity (small accelerations) on thermal diffusion. A three-dimensional numerical model is implemented for the study of various g-jitter scenarios. It is found that the ISS microgravity environment can cause the diffusion process to depart from the ideal behaviour in some circumstances. Such departure varies with the magnitude of the g-jitters and may be insignificant when the g-jitter magnitude is below a threshold value around 10μg. Furthermore, the magnitude of the g-jitters is not the only factor affecting the diffusion process. It has to be evaluated together with the frequency and alignment of the g-jitters. In general, this comparative study indicates that the ISS is an effective reduced gravity platform for experimental diffusion studies.

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Keywords

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