scholarly journals Numerical Simulation Of Thermodiffusion Subjected To Different Gravity Fields

2021 ◽  
Author(s):  
Ahmad Khoshnevis
Keyword(s):  
Space Station ◽  
Microgravity Environment ◽  
Convection Flow ◽  
External Excitation ◽  
International Space ◽  
Residual Gravity ◽  
Gravity Fields ◽  
Buoyancy Driven Flows ◽  
Computational Fluid Dynamics Cfd ◽  
Strong Convection

In this work, a typical thermodiffusion experiment on a binary mixture is simulated numerically using a two-dimensional computational fluid dynamics (CFD) code. Three scenarios for gravity have been studied: residual, pure oscillatory, and microgravity micro-accelerations. It was found that less separation of mixture components in the presence of strong gravity fields is due to the formation of buoyancy-driven flows. For the case of pure oscillatory gravity, the effects of the frequency and amplitude are discussed in detail. A critical vibrational Rayleigh number is proposed above which the diffusion process is highly affected by the external excitation. For the case of the microgravity environment, quasi-steady accelerations and g-jitter, both of which are found on the International Space Station, have been considered. Results show g-jitter has a minimal effect on the thermodiffusion experiment. The effects of the residual gravity field were also found to be insignificant in stimulating a strong convection flow.

scholarly journals Numerical Simulation Of Thermodiffusion Subjected To Different Gravity Fields

2021 ◽  
Author(s):  
Ahmad Khoshnevis
Keyword(s):  
Space Station ◽  
Microgravity Environment ◽  
Convection Flow ◽  
External Excitation ◽  
International Space ◽  
Residual Gravity ◽  
Gravity Fields ◽  
Buoyancy Driven Flows ◽  
Computational Fluid Dynamics Cfd ◽  
Strong Convection

In this work, a typical thermodiffusion experiment on a binary mixture is simulated numerically using a two-dimensional computational fluid dynamics (CFD) code. Three scenarios for gravity have been studied: residual, pure oscillatory, and microgravity micro-accelerations. It was found that less separation of mixture components in the presence of strong gravity fields is due to the formation of buoyancy-driven flows. For the case of pure oscillatory gravity, the effects of the frequency and amplitude are discussed in detail. A critical vibrational Rayleigh number is proposed above which the diffusion process is highly affected by the external excitation. For the case of the microgravity environment, quasi-steady accelerations and g-jitter, both of which are found on the International Space Station, have been considered. Results show g-jitter has a minimal effect on the thermodiffusion experiment. The effects of the residual gravity field were also found to be insignificant in stimulating a strong convection flow.

scholarly journals Design of a Small-Scale Experimental Model of the International Space Station Crew Quarters for a PIV Flow Field Study

2019 ◽  
Vol 111 ◽  
pp. 01045
Author(s):  
Matei-Razvan Georgescu ◽  
Ilinca Nastase ◽  
Amina Meslem ◽  
Mihnea Sandu ◽  
Florin Bode
Keyword(s):  
International Space Station ◽  
Numerical Models ◽  
Space Station ◽  
Scale Model ◽  
Microgravity Environment ◽  
Small Scale ◽  
Piv Measurements ◽  
International Space ◽  
The Subject ◽  
Small Scale Model

An attempt at improving the ventilation solution for the crew quarters aboard the International Space Station requires a thorough understanding of the flow dynamics in a microgravity environment. An experimental study is required in order to validate the numerical models. As part of this process, a small-scale model was proposed for a detailed study of the velocity field. PIV measurements in water offer high quality results and were chosen for the subject. Following certain similitude criteria, an equivalence can be found between the results of these measurements and the real ventilation scenario. This paper describes the development process of this small-scale model as well as its performance in the initial test runs. Details regarding the advantages and weaknesses of this first model are the core of the paper, with the intention of aiding researchers in their design of similar models. The conclusion presents future steps and proposed improvements to the model.

Microbial Observatory Research in the International Space Station and Japanese Experiment Module “Kibo”

2015 ◽  
Vol 10 (6) ◽  
pp. 1025-1030 ◽  
Author(s):  
Masaki Shirakawa ◽  
◽  
Fumiaki Tanigaki ◽  
Takashi Yamazaki ◽  
Keyword(s):  
International Space Station ◽  
Space Station ◽  
Space Mission ◽  
The Body ◽  
Current Status ◽  
Microgravity Environment ◽  
International Space ◽  
Research Areas ◽  
Experiment Module

The International Space Station (ISS) is a completely closed environment that offers a long-term microgravity environment. It is a unique environment where microbes can fly and attach themselves to devices or humans, especially the exposed parts of the body and head. The ongoing monitoring and analysis of microbes and their movement inside the Japanese Experiment Module (named “Kibo”) of the ISS are intended to study the effects of microbes on humans and prevent health hazards caused by microbes during a long-term space mission. This paper describes the current status and future plan of Japanese microbiological experiments to monitor microbial dynamics in Kibo. It also describes the future prospective and prioritized microbiological research areas based on the “Kibo utilization scenario towards 2020 in the field of life science.” Given the microbial research in space being actively conducted by the USA, NASA and international activities are also reported.

scholarly journals VEG-01: Veggie Hardware Validation Testing on the International Space Station

2017 ◽  
Vol 2 (1) ◽  
Author(s):  
Gioia D. Massa ◽  
Nicole F. Dufour ◽  
John A. Carver ◽  
Mary E. Hummerick ◽  
Raymond M. Wheeler ◽  
...  
Keyword(s):  
International Space Station ◽  
Space Station ◽  
Fungal Growth ◽  
Microgravity Environment ◽  
Vegetable Production ◽  
Romaine Lettuce ◽  
International Space ◽  
Excess Water ◽  
Validation Testing ◽  
Test Plants

AbstractThe Veggie vegetable production system was launched to the International Space Station with three sets of test plants for an initial hardware validation test, designated VEG-01. VEG-01A and B featured the crop ‘Outredgeous’ red romaine lettuce, while VEG-01C tested ‘Profusion’ zinnia plants for longer duration growth and flowering characteristics. Irrigation of plants in all three growth studies presented a challenge, with lettuce suffering from inadequate water and zinnia suffering from excess water. Direct plant pillow watering by crew members enabled plant growth, and returned samples from the first crop, VEG-01A, indicated that food safety was acceptable. VEG-01B plants at harvest were split to allow for on-orbit crew consumption as well as science sample return. Direct-watered zinnias suffered fungal growth and other physiological stresses, but two plants survived and these produced numerous flowers. The VEG-01 series allowed a large amount of data on system performance, human factors, procedures, microbiology, and chemistry of space-grown plants to be gathered. Observations from these tests are helping to drive future hardware modifications and provide information on food crop growth and development in a microgravity environment.

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