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Technical Paper

Internal and External Flow Simulation Using Multizone Euler/Navier-Stokes Aerodynamic Methods

1990-09-01
901856
A computational method based on a cell-centered, finite-volume spatial discretization and explicit time-stepping algorithm for solving the Euler and Navier-Stokes equations is used to simulate inviscid and viscous flow about configurations including a diverging nozzle, a 74 degree delta wing, and a Mach 6 Waverider. Solutions are obtained using patched multizone grids with both matching and different grid densities across zonal interfaces and are correlated with analytical solutions and experimental data. The computational results increase the confidence in applying Euler and Navier-Stokes solvers to the more complex mixed internal/external flows associated with complete aircraft configurations.
Technical Paper

Performance Testing as a Determinant of Fitness-For-Duty

1990-09-01
901870
Performance testing provides an important complement to urine testing as a determinant of fitness for duty. Performance testing can be conducted immediately to screen out impaired workers before they undertake safety related job functions. Urine testing involves the expense and delay of laboratory testing, and results relate more to life style than current on-the-job performance capability. This paper reviews performance based testing and discusses the development and application of two performance based screening devices. One device has the capability of rapidly screening for impaired psychomotor performance given previous baseline data. The second device provides the potential for screening psychomotor and divided attention performance without prior experience or baseline data.
Technical Paper

Training System Requirements-A Training System Developer's Viewpoint

1990-09-01
901945
The definition of a conceptual Joint Primary Aircraft Training Systems (JPATS) for use in USAF and USN pilot training re quired the development of an algorithm to select the appropriate training media and of a methodology to compare the training effectiveness of the aircraft candidates for the system. The media selection algo rithm uses cognitive and behavioral compo nents of the skills to identify the appro priate training media. The aircraft comparison methodology used a series of performance and system characteristics to generate a training difficulty index (relative to the current T-37 baseline). This index was used to estimate the skill level achieved at aircraft mastery and the length of time to achieve mastery. This paper discusses the general JPATS study effort with the focus on these two development efforts.
Technical Paper

Proven Dynamic Modeling Techniques for Concurrent Design and Analysis of ECS Controllers

1990-07-01
901234
An F-16 Environmental Control System (ECS) computer model was developed to assist engineers with the design and development of ECS control algorithms. This model consists of many dynamic component modules (ducts, valves, heat exchangers, compressor, etc.). The accuracy of this analysis tool was verified by comparing model results to F-16 ECS test-stand and test-aircraft data - the verification results are in excellent agreement. Presented in this paper are modeling techniques, model descriptions, verification results, discussion of test-stand data reduction and comparison, and discussion of the comparison with flight-test data. Our F-16 ECS model is a viable and accurate simulation tool for concurrent analysis and design of environmental control systems.
Technical Paper

Water Recycling in Space

1990-07-01
901247
The results of the preliminary studies of water recycling for ESA are presented. The main conclusion is that the treatments for all waste waters, except urine, should consist of 1) Pretreatment (acidification, H202-addition, and filtration) 2) Reverse osmosis 3) Oxidation (H2O2 + UV light) 4) Reverse osmosis (neutral pH) Together with reject from reverse osmosis (RO), urine is treated by Vapour Compression Distillation (VCD). Microbiological studies have been made, and practical experiments with RO on shower water are mentioned. It is shown that up to 98% recovery can be obtained with a power consumption of 45-60 Wh/liter.
Technical Paper

Clinical Laboratory Diagnosis for Space Medicine

1990-07-01
901263
Analogous to Earth-based medical care facilities, space-based facilities must provide capability for laboratory diagnosis. A clinical laboratory system, based on commercially available devices or technologies, is being designed for space station Freedom that can be used by the crew medical officer to provide analysis of discrete samples of blood and other biological fluids. Clinical chemistry, blood gas analysis, hematology, and microbiology are planned to be available at the space station as components of the Crew Health Care System. As with many space systems, ease of use, compact size and reliability are primary guidelines. Due to the many types of blood and urine analyses that are available, clinical chemistry may be the most frequently used analytical procedure for space medicine.
Technical Paper

European Two-Phase Heat Transport Technology Test Bed Results

1990-07-01
901271
Under the COLUMBUS Preparatory Support Technology Programme, the European Space Agency has coordinated the development of critical components for a European pumped two-phase heat transport system. The critical components are Evaporator Cold Plate (Dornier GmbH), Evaporative Heat Exchanger (Aeritalia) being an interface component to an external loop, Heat Rejection Interfaces/Condensers (Fokker), active Accumulator/Control Reservoir (British Aerospace) and Vapour Quality Sensors (Dornier GmbH and NLR). They have been incorporated into a flexible and fully instrumented test bed at BAe. The test bed is designed to evaluate the performance of a complete representative loop with heat loads up to 15 kW and primary loop lengths up to 40 metres. It includes an implementation of algorithms developed at Fokker and NLR for the control of evaporator inlet temperature conditions, vapour temperature setpoint and vapour quality.
Technical Paper

Fatique and Electromagnetic Interference Test for Electro-Impulse De-Icing

1989-04-01
891062
Electro-Impulse De-Icing (EIDI) has been studied and developed at Wichita State University for the past six years in ten icing wind tunnel tests and three sets of flights tests. However, questions remained about the system endurance over a lifetime of use and about electromagnetic compatibility. These were addressed in tests of both metal and composite leading edges. Energy levels used were those determined necessary in the earlier tunnel and flight tests. Failures for the aluminum leading edges were found only in poorly designed coil brackets and in a pre-stressed rivet hole. No damage could be found with the composite model. Electromagnetic radiation was found to be well contained in an aluminum wing. Exposed lead wires were high power emitters and these had to be fully shielded for the composite model to meet the specifications. The emissions were broadband with no significant peak frequencies. ICE ACCUMULATION IN FLIGHT is a well recognized danger.
Technical Paper

Application of EQUIVALE Software to the ESATAN Conductive Model Reduction

1993-07-01
932132
One way to increase thermal software performance has been developed at AEROSPATIALE Cannes by means of a condensation algorithm for conductive models (EQUIVALE). The benefit of this improvement is exportable to other software packages by developing specific interfaces. Therefore, two gateways are now available to perform ESATAN conductive models condensation: the first (ESAEQU) translates the initial ESATAN input deck into the different files required by EQUIVALE; the second (EQUESA) generates a new ESATAN input deck including the equivalent conductances provided by EQUIVALE. Three examples of application are described hereafter: the first (RADIATOR PANEL) illustrates the condensation processing coupled to ESATAN, the second (TV-SAT/TDF), more realistic, refers to a flight model in the frame of the AEROSPATIALE Thermal Software environment and the third (TÜRKSAT) shows the optimum use of EQUIVALE with the combination of both PLATEAU and EQUIVALE software packages.
Technical Paper

Microcomputer Spacecraft Thermal Analysis Routines (MSTAR) Phase I: The User Interface

1993-07-01
932136
The Microcomputer Spacecraft Thermal Analysis Routines (MSTAR) software package is being developed for NASA/Goddard Space Flight Center by Swales and Associates, Inc. (S&AI). Thermal analysis of large-scale spacecraft are currently being performed with industry standard programs such as SSPTA1, VIEW2, and TRASYS3. These software packages, however, are based on solution algorithms developed as much as 25 years ago. Many of the algorithms used in these programs are based on software and hardware available at that time. In recent years, the computer industry has made tremendous technological advances in providing powerful yet inexpensive desktop computers capable of competing with small mainframe computers. In December 1992, S&AI was awarded a Phase I Small Business Innovative Research contract from NASA to develop a microcomputer based thermal analysis program to replace the current SSPTA and TRASYS programs.
Technical Paper

Thermohydraulic Analysis of the Cooling Air Flow in a Rack

1993-07-01
932134
Manned space laboratories like the US Space Station Freedom or the european COLUMBUS APM are equipped with so-called racks for subsystem and payload accommodation. An important resource is air for cooling the unit internal heat sources, the avionics air. Each unit inside the rack must be supplied with sufficient amount of air to cool down the unit to the allowable maximum temperature. In the course of the COLUMBUS ECLSS project, a thermohydraulic mathematical model (THMM) of a representative COLUMBUS rack was developed to analyse and optimise the distribution of avionics air inside this rack. A sensitivity and accuracy study was performed to determine the accuracy range of the calculated avionics air flow rate distribution to the units. These calculations were then compared to measurement results gained in a rack airflow distribution test, which was performed with an equipped COLUMBUS subsystem rack to show the pressure distribution inside the rack.
Technical Paper

Preflight and Postflight Microbiological Results from 25 Space Shuttle Crews

1993-07-01
932139
Clinical-microbiological investigations are an important aspect of the crew health stabilization program. To ensure that space crews have neither active nor latent infections, clinical specimens, including throat and nasal swabs and urine samples, are collected at 10 days (L-10) and 2 days (L-2) before launch, and immediately after landing (L+0). All samples are examined for the presence of bacteria and fungi. In addition, fecal samples are collected at L-10 and examined for bacteria, fungi and parasites. This paper describes clinical-microbiological findings from 144 astronauts participating in 25 Space Shuttle missions spanning STS-26 to STS-50. The spectrum of microbiological findings from the specimens included 25 bacterial and 11 fungal species. Among the bacteria isolated most frequently were Staphylococcus aureus, Enterobacter aerogenes, Enterococcus faecalis, Escherichia coli, Proteus mirabilis and Streptococcus agalactiae.
Technical Paper

New Technologies for On-Line Water Quality Monitoring

1993-07-01
932181
Water is recycled on Space Station Freedom (SSF) to avoid the high logistical cost of fresh water resupply. The water system produces potable water from humidity condensate, wash water, fuel cell water transferred from the shuttle, and urine. The processes include vapor compression distillation of urine, heat sterilization, sorption beds, organics oxidation, gas-liquid separation, filtration, and biocide addition. Treated water quality is monitored by a Process Control Water Quality Monitor (PCWQM), which reports water quality to the SSF data management system. Specifically, the PCWQM is an untended, continuous process water quality monitor which measures conductivity, pH, Total Organic Carbon (TOC), temperature, and iodine biocide concentration. TOC is measured by converting organic carbon into CO2 by UV oxidation and using a photometric cell to determine the quantity of gas. Conductivity is measured using a 1000 Hz conductivity cell, compensated for temperature.
Technical Paper

Minimum Ventilation Velocities for Maintaining Space Station Crew Comfort

1993-07-01
932191
The ventilation velocity requirements for crew comfort and heat transfer were assessed, as one of several initiatives to ensure that sufficient electric power will be available for Space Station Freedom during the early Man-Tended Capability (MTC) Phase of operations. A rigorous heat transfer analysis, to accommodate microgravity and reduced pressure conditions, was conducted to characterize cabin air effectiveness in transferring metabolic heat away from crewmembers. Maximum possible sweat evaporation rates were estimated based upon rigorous mass transfer correlations. In the range of low work rates applicable to MTC, no single mechanism dominated the heat transfer. Those mechanisms not dependent upon ventilation velocities, radiation and respiration, appeared to be as important, under the nominal conditions, as forced convection and sweat evaporation. It was shown that ventilation velocities could be lower than 15 feet per minute, and still provide sufficient heat flux.
Technical Paper

Comparative Test Data Assessment and Simplified Math Modelling for the Vapor Compression Distillation Subsystem

1993-07-01
932194
Space Station Freedom (SSF) has an extended mission duration of 30 years. Trade studies for extended missions of manned spacecraft almost invariably show that large resupply weight and consequent cost savings can be achieved by recovering potable water from wastewater sources. This rationale has led to the present baseline Water Recovery and Management (WRM) system for the Permanently Manned Capability (PMC) phase of SSF. The baseline WRM includes the Vapor Compression Distillation (VCD) subsystem for recovering water from urine. This process serves as a preliminary processing step in achieving potable water from wastewater sources. The basic principle of the VCD is that water is evaporated from urine and then condensed in a zero-gravity device containing an evaporator and a condenser in a rotating drum. The VCD was selected for the baseline WRM following the assessment of test results from competitive urine processing subsystems obtained from the Comparative Test (CT) program.
Technical Paper

Modeling, Simulation, and Analysis of the Thermal and Pressure Control System for a Closed Crop Growth Chamber

1993-07-01
932167
This paper presents details of the mathematical modeling and simulation of the shoot side subsystem of a closed crop growth chamber. A discussion of the derivation of the mathematical model and the development of the simulation is presented, including a computer simulation with temperature control. The objective is to design a temperature and pressure control system.
Technical Paper

Advanced Development of the Regenerative Microbial Check Valve

1993-07-01
932175
The Microbial Check Valve (MCV) is a reloadable flow-through canister containing iodinated ion exchange resin, which is used aboard the Shuttle Orbiter as a disinfectant to maintain water potability. The MCV exhibits a significant contact kill and imparts a biocidal residual I2 concentration to the effluent. MCVs in current use have nominal 30 day lives. MCVs baselined for Space Station Freedom will have 90 day lives, and will require replacement 120 times over 30 years. Means to extend MCV life are desirable to minimize resupply penalties. New technology has been developed for fully autonomous in situ regeneration of an expended MCV canister. The Regenerative Microbial Check Valve (RMCV) consists of an MCV, a packed bed of crystalline I2, a flow diverter valve, an in-line iodine monitor and a microcontroller. During regeneration, flow is directed first through the packed I2 bed and then into the MCV where the resin is replenished.
Technical Paper

Characterization of Spacecraft Humidity Condensate

1993-07-01
932176
When construction of Space Station Freedom reaches the Permanent Manned Capability stage, plans call for the Water Recovery and Management Subsystem to treat distilled urine, spent hygiene water, and humidity condensate in order to reclaim water of potable quality. The reclamation technologies currently baselined to process these wastewaters include adsorption, ion exchange, catalytic oxidation, and disinfection. To ensure that baselined technologies will be able to effectively remove those compounds that present health risks to the crew, the National Research Council has recommended that additional information be gathered on specific contaminants in wastewaters representative of those to be encountered on Space Station. This paper reports the efforts by the Water and Food Analytical Laboratory at the Johnson Space Center to enlarge the database of potential contaminants in humidity condensate.
Technical Paper

Integrated Active Thermal Control System Analysis of Space Station Freedom Operational Scenarios

1993-07-01
932200
This paper describes the integrated active thermal control systems analysis of proposed operational scenarios for Space Station Freedom. The analysis uses detailed mathematical models of Freedom's water, air, and ammonia cooling loops. Also included, is an electrical connectivity model to provide for proper equipment response due to any failure, either electrical or thermal. The operational scenarios analyzed for this paper are developed by the National Aeronautics and Space Administration in order to provide various disciplines with realistic operational conditions and station construction conditions. The station construction process generates many unique conditions and configurations. During this time, many of the normal system backups are temporarily disabled or reduced in effectiveness.
Technical Paper

Application of Hair Analysis for Biological Monitoring of Toxic Substances in Space

1993-07-01
932095
Human scalp hair is increasingly regarded as a valuable indicator tissue for biological monitoring of environmental exposure to toxic substances. Hair provides both current and past records of exposure during prolonged periods of time. To validate hair monitoring for assessment of toxic substances in space, a unique biological model was developed. Human scalp grafts were transplanted to athymic BALB/c-nu/nu nude mice and then animals were exposed continuously over 2 months, using implanted osmotic pumps, to methylmercury (MeHg), a substance known to be incorporated into hair. Mercury concentrations in hairs were determined using X-ray fluorescence (XRF) spectrometry by segmental analysis of single strands. Blood, skin and brain concentrations of methylmercury were measured by cold vapor analysis. Human scalp hair grown in nude mice showed long-term persistence of human characteristics.
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