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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.

Three-dimensional flow and temperature distributions in a passenger compartment are very important for evaluating passenger comfort and improving A/C system design. In the present study, the Reynolds-averaged Navier-Stokes equations and the energy transport equation were solved, by both quasi-steady and full transient approaches, to simulate a passenger compartment cooling process. By comparing the predictions with experimental results for a simplified GM-10 passenger compartment, the accuracy of the simulation was assessed. Throughout the 800-second period, good agreement was observed between the measured breath-level air temperatures and the prediction of the transient simulation. The quasi-steady simulation underpredicted air temperatures at the very early stage of the cooling process. However, after 200 seconds of cool down, the quasi-steady simulation predicted air temperatures equally as well as the full transient simulation.