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The objective of this study is to evaluate ventilation efficiency regarding to the International Space Station (ISS) cabin ventilation during the ISS assembly mission 1J. The focus is on carbon dioxide spatial/temporal variations within the Node 2 and attached modules. An integrated model for CO2 transport analysis that combines 3D CFD modeling with the lumped parameter approach has been implemented. CO2 scrubbing from the air by means of two ISS removal systems is taken into account. It has been established that the ventilation scheme with an ISS Node 2 bypass duct reduces short-circuiting effects and provides less CO2 gradients when the Space Shuttle Orbiter is docked to the ISS. This configuration results in reduced CO2 level within the ISS cabin.

The paper presents the results of a CFD study for predictions of ventilation characteristics and convective heat transfer within the Shuttle Orbiter middeck cabin in the presence of seven suited crewmember simulation and Individual Cooling Units (ICU). For two ICU arrangements considered, the thermal environmental conditions directly affecting the ICU performance have been defined for landing operation. These data would allow for validation of the ICU arrangement optimization.

Computational Fluid Dynamics airflow models for the Waste and Hygiene Compartment (WHC) in the U.S. Laboratory module and Node 3 were developed and examined. The International Space Station (ISS) currently provides human waste collection and hygiene facilities in the Russian Segment Service Module (SM) which supports a three person crew. An additional set of Russian hardware, known as the system, is planned for the United States Operational Segment (USOS) to support expansion of the crew to six persons. Integration of the Russian system into the USOS incorporates direct Environmental Control and Life Support System (ECLSS) interfaces to allow more autonomous operation. A preliminary design concept was used to create a geometry model to evaluate the air interaction with the module cabin at varied locations and performance of the avionics fan placed in WHC. The Russian and the privacy protection bump-outs (Kabin) were included into the present modeling.

The aim of the study is to understand risks associated with a crew member accessing behind the closeout panel or space. Since there is a possibility that a particular closeout space is filled with a harmful gas mixture that is different from the cabin atmosphere, the time needed to ventilate this space should be evaluated. The three-dimensional Computational Fluid Dynamics (CFD) model developed for prediction of time-dependent turbulent flow and concentration fields inside and near a suddenly-opened box is described in the paper. Several cases with different positions of the closeout space, initially filled with pure oxygen, are analyzed under the U.S. Laboratory (USL) ventilation conditions. A simplified flow model, where a suddenly-opened box is ventilated by uniform external throughflow, is considered as well.

This study covers CFD simulation of the air ventilation within the Assembly Complete stage of ISS on-orbit configuration of twelve modules. An assessment of ISS cabin aisle way airflow characteristics was performed on the basis of the integrated model computations. Both the quantitative evaluation of velocity distribution and qualitative analysis of three-dimensional airflow are presented.

This paper reports results of Computational Fluid Dynamics (CFD) analysis of carbon dioxide (CO2) gradient variations in twelve ISS modules. Computations were performed using two 3D integrated models: one from the U.S. Laboratory to the forward end, and the other from the U.S. Laboratory to the aft end of the ISS. Operation of the CO2 removal systems and CO2 generation among six International Space Station (ISS) crewmembers' metabolic processes were included in the model. For several crew location scenarios, a detailed analysis of the CO2 gradients and time evolution in zones potentially occupied by astronauts is presented. In general, the paper gives an extended example of the application of CFD analysis to complex problems related to the quality of the cabin air.

Proper design of the air ventilation system is critical to maintaining a healthy environment for the ISS crew. In this study, a computational fluid dynamic model was used to model the air circulation in Node 1 to identify the locations where there are low air velocities under nominal operating conditions and several reduced ventilation flow conditions. The reduced ventilation flow conditions analyzed were loss of cabin air fan, loss of inter-module ventilation from Node 1 to the US Lab, and loss of inter-module ventilation from the airlock to Node 1. For nominal operation of the ventilation system, about 5% of the node had air velocity of between 1 and 5 ft/min and 14% of the node had air velocity of between 5 and 10 ft/min. Loss of the cabin air fan and loss of Lab inter-module ventilation did not have a significant impact on the percentage of the node that would have low air circulation.

This CFD study is aimed at evaluation of the ventilation characteristics within the ISS Node 1 with the Advanced Resistive Exercise Device (ARED) protrusions into ECLS keep-out zones. An assessment of Node 1 airflow characteristics in the presence of the ARED and a human body simulation model has been performed for the current on-orbit configuration of the Node 1 ventilation system. Both the quantitative velocity distribution analysis and qualitative three-dimensional airflow evaluation have shown that the installation of the ARED in the Node 1 radial bay produces a minimal impact on the cabin ventilation characteristics and the crew.

This paper presents results of the CFD study aimed at evaluation of the CO2 concentration within the Shuttle Orbiter Middeck during the Launch on Need (LON) Crew Rescue flight. An assessment of the Middeck ventilation characteristics has been performed for two possible ventilation arrangements. A recommendation to use the ventilation system configuration with the open aft floor diffuser has been made on the basis of a three-dimensional airflow and CO2 gradient analysis.

Crew health is dependent on the concentration of carbon dioxide in the atmosphere breathed. Often, models used for concentration have used the assumption that each module of the space station is well mixed, i.e. that the CO2 concentration is constant throughout the module. In this paper, Computational Fluid Dynamics (CFD) modeling is used to assess and validate the accuracy of that assumption. The concentration of carbon dioxide as calculated by CFD was compared to the concentration as calculated by a lumped parameter model. The assumption that the module is well mixed allows the use of relatively simple models, which can be developed and run quickly in order to support decisions for on-orbit analysis. CFD models generate more detailed information, such as CO2 gradients within the modules and airflow and mixing characteristics. However, CFD models, particularly transient models, take longer to develop and use.

Ventilation characteristics of the Columbus module are numerically predicted on the basis of the Reynolds-Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) approaches. Effects of air supply diffuser modeling on computed flow are analyzed. An “effective diffuser” model that considerably reduces the number of computational cells for Columbus CFD ventilation analysis is proposed and tested. The computational models are verified by a comparison with the experimental data available. Special attention is paid to distinctions in fields of the time-averaged absolute velocity magnitude and the whole mean velocity that are due to the contribution of large-scale fluctuations. A technique to evaluate spatial distribution of the time-averaged absolute velocity magnitude using data of RANS steady-state predictions is suggested.

The Japanese Experimental Module (JEM) Pressurized Module (PM) is a facility where astronauts conduct experiments or control the total JEM facility. Inside the PM, the air composition, temperature and humidity are controlled so as to be comfortable for astronauts' activity all the time. The verification of the on-orbit performance of the functions constituting a manned space system is one of the critical points. Computational Fluid Dynamics (CFD) simulation technology is utilized to characterize and investigate the airflow in the JEM for various operating conditions. The development of a successful CFD model for International Space Station (ISS) operation is useful because there are always off-nominal and other contingency operations, which might occur and could be analyzed using an existing CFD model. This paper also presents the cabin ventilation test data obtained from the JEM flight module.

The objectives of this investigation were to verify the air ventilation characteristics of the U. S. Airlock and to ensure the adequacy of inter-module ventilation (IMV) of the International Space Station (ISS) Flight 7A configuration. There are three operating modes for the air ventilation in the U. S. Airlock: (1) Open Hatch configuration, (2) Closed Hatch configuration and (3) Housekeeping mode. In this study, computational fluid dynamics (CFD) models with the geometrical details representing each mode of the Airlock's operation was built. Proper airflow boundary conditions that represent the operation of the Airlock's Common Cabin Air Assembly (CCAA) and the inter-module ventilation were imposed for the subsequent CFD simulations. Based on the results obtained in this study, the performance of the Airlock ventilation system is marginally acceptable at CCAA fan running at 3600 rpm for both Open Hatch and Closed Hatch operations.

Accumulation and re-breathing of CO2 in expired air has been investigated as a possible indication for crew discomfort onboard the International Space Station (ISS) Service Module crew quarters. In addition, inadequate airflow contributes to increasing temperature that also leads to crew discomfort. The objective of this study is to evaluate possible medical hazards that can occur when a crewmember is sleeping in the crew quarter of the ISS Service without proper ventilation. This paper investigates a projected increase in CO2 in the enclosure under a no ventilation scenario. A Computational Fluid Dynamics (CFD) model of the crew quarters and of a human body are built to investigate the ventilation profile and the CO2 concentration inside the volume of the crew quarters. Respiratory characteristics of a typical 180-pound crewmember are simulated. The results for the distribution and concentration of expired air at different time intervals and at different locations are presented.

The effects of testing cabin ventilation in gravity to meet a requirement for ventilation on orbit were analyzed. Buoyancy is due to the combined presence of a density gradient within the fluid and a body force that is proportional to the fluid density. Since gravity cannot be removed, the test must be conducted with air at as near to constant density as practical in order to remove buoyancy effects. The effects of gravity induced buoyancy force on the velocity field was analyzed by the Richardson number. Computational Fluid Dynamics (CFD) analysis was performed to verify the theoretical methods. The velocity data for a 1-g and a no gravity case were compared. The ratio between local velocity and free stream velocity, u/U∞ were analyzed for the dimensionless parameter, η (= y ✓ U∞/νx). There is a relatively sharp rise in the profile near the wall and an overshoot of the velocity beyond its free stream value.

The U. S. Laboratory (USL) module was added to the International Space Station (ISS) in Flight 5A, which would boost the Environmental Control & Life Support System (ECLSS) functional capabilities of the ISS. In the USL cabin aisle way, the air circulation is provided by a Temperature & Humidity Control (THC) system. To provide adequate ventilation under various open/close combinations of the rack panels, it would be very challenging by conducting many tests prior to the launch of Flight 5A. Computational fluid dynamics (CFD) simulation technology is utilized to investigate the airflow in the U.S. Lab for various operating scenarios. A CFD model, which includes the supply diffusers, the return registers, the ventilation of the temporary crew quarter, the gap between the outer pressure shell and all the racks, is modeled. The ventilation performance for the cabin aisle way and air behind panels is addressed.

During a recent International Space Station (ISS) flight (Flight 2A.1), an improper ventilation event might have occurred and resulted in stuffy air, as reported by the crew. Even though no air samples were analyzed, the accumulation of metabolic CO2 in the ISS was suspected as the cause of the crew sickness. With no possibility of conducting an on-orbit test of this kind, it was decided to utilize Computational Fluid Dynamics (CFD) analysis to investigate this problem. Based on the Flight 2A.1 and 2A.2a configurations, a CFD model of the air distribution system was built to characterize airflow between the ISS elements. This model consists of Inter-module Ventilation (IMV) covering the Functional Cargo Block (FGB), two Pressurized Mating Adapters (PMA-1 and PMA-2), the Node-1, and portions of the Orbiter volume.

This paper presents the basic test data obtained from tests of a cabin air distribution system in a simulated Space Station Man-Tended Capability (MTC) configuration and correlations of some of this data with the results from analytical modeling of the test setup flow conditions. The MTC configuration simulated in the test setup includes: Lab-A, the Node, the Cupola, and the Pressurized Module Adaptor (PMA). The test data and analytical data presented are confined to those for the Lab module. The cabin air distribution system controls the flow of air in the open space of a Space Station module. In order to meet crew comfort criteria the local velocities for this cabin air are required to be distributed within a specified range with upper and lower limits.