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The 1977 Clean Air Act Amendments allow the U.S. Environmental Protection Agency to set high altitude emission standards for 1981-83, but specify that any such standards may not be more stringent than comparable sea level standards -- relative to 1970 emission levels. Since available high altitude emission data from 1970 models were incomplete and controversial, the Motor Vehicle Manufacturers Association contracted with Automotive Testing Laboratories, Inc. to test a fleet of 25 1970 cars. Results of the test program showed average increases in emissions at Denver's altitude, compared to sea level, to be about 30% for evaporative HC, 57 to 60% for exhaust HC, 215 to 247% for CO and -46 to -47% for NOx. Corresponding HC and CO exhaust emission baselines would be 6.4 to 6.6 and 108 to 118 g/mi respectively.

The main objective of the current paper was to investigate the fluid flow and pressure loss characteristics of DPF substrates with asymmetric channels utilizing 3-D Computational Fluid Dynamics (CFD) methods. The ratio of inlet to outlet channel width is 1.2. First, CFD results of velocity and static pressure distributions inside the inlet and outlet channels are discussed for the baseline case with both forward and reversed exhaust flow. Results were also compared with the regular DPF of same cell structure and wall material properties. It was found that asymmetrical channel design has higher pressure loss. The lowest pressure loss was found for the asymmetrical channel design with smaller inlet channels. Then, the effects of DPF length and filter wall permeability on pressure loss, flow and pressure distributions were investigated.

The general benefits of automation are well documented. Order of magnitude improvements are achievable in processing speeds, production rates, and efficiency. Other benefits include improved process consistency (inversely, reduced process variation), reduced waste and energy consumption, and risk reduction to operators. These benefits are especially true for the automation of the aerospace paint removal (or "depaint") processes. Southwest Research Institute® (SwRI®) developed and implemented two systems in the early 1990s for depainting full-body fighter aircraft at Robins Air Force Base (AFB) at Warner Robins, Georgia, and Hill AFB at Ogden, Utah. These systems have been in production use, almost continuously for approximately 20 years, for the depainting of the F-15 Eagle and the F-16 Falcon fighter aircraft, respectively.

This paper examines the theoretical worst case of normal headform impact on an infinitely rigid surface with the help of a dynamic spring-mass model. It is pointed out that the current approach is not an actual representation of any vehicle upper interior but is useful in gaining insight into the headform impact phenomenon and determining how to further enhance design. After considering force-deflection characteristics of a variety of commonly used headform impact protection countermeasures, a mathematical model is set up with spring properties that approximate those of physical countermeasures. Closed-form solutions are derived for various dynamic elasto-plastic phases including elastic unloading and contact. A parametric study is then carried out with HIC(d) as the dependent variable, and spring stiffness, yield force and spring length (representing countermeasure crush space) as the design variables.

An analysis model has been developed for analyzing/optimizing the integration of a carbon dioxide removal assembly (CDRA), CO2 compressor, accumulator, and Sabatier CO2 reduction assembly. The integrated model can be used in optimizing compressor sizes, compressor operation logic, water generation from Sabatier, utilization of CO2 from crew metabolic output, and utilization of H2 from oxygen generation assembly. Tests to validate CO2 desorption, recovery, and compression had been conducted in 2002-2003 using CDRA/Simulation compressor set-up at NASA Marshall Space Flight Center (MSFC). An analysis of test data has validated CO2 desorption rate profile, CO2 compressor performance, CO2 recovery and CO2 vacuum vent in the CDRA model. Analysis / optimization of the compressor size and the compressor operation logic for an integrated closed air revitalization system is currently being conducted

When technologies are traded for incorporation into vehicle systems to support a specific mission scenario, they are often assessed in terms of “Technology Readiness Level” (TRL). TRL is based on three major categories of Core Technology Components, Ancillary Hardware and System Maturity, and Control and Control Integration. This paper describes the Technology Readiness Level assessment of the Carbon Dioxide Reduction Assembly (CRA) for use on the International Space Station. A team comprising of the NASA Johnson Space Center, Marshall Space Flight Center, Southwest Research Institute and Hamilton Sundstrand Space Systems International have been working on various aspects of the CRA to bring its TRL from 4/5 up to 6. This paper describes the work currently being done in the three major categories. Specific details are given on technology development of the Core Technology Components including the reactor, phase separator and CO2 compressor.

The current operation of the International Space Station (ISS) calls for the oxygen used by the occupants to be vented overboard in the form of CO2, after the CO2 is scrubbed from the cabin air. Likewise, H2 produced via electrolysis in the oxygen generator is also vented. NASA is investigating the use of the Sabatier process to combine these two product streams to form water and methane. The water is then used in the oxygen generator, thereby conserving this valuable resource. One of the technical challenges to developing the Sabatier reactor is transferring CO2 from the Carbon Dioxide Removal Assembly (CDRA) to the Sabatier reactor at the required rate, even though the CDRA and the Sabatier reactor operate on different schedules. One possible way to transfer and store CO2 is to use a mechanical compressor and a storage tank.

This paper discusses the development of criteria necessary to establish reliable lunar exploration and construction vehicle concepts. To establish the basis for the development of these criteria, an exploration mission using the presently conceived Apollo launch vehicle system is described. The criteria resulting from the study of the contribution made by the hostile lunar environment and the life support system requirements within the framework of the selected mission are established. Soils testing in a hard vacuum is described, as are tests of models under simulated lunar terrain environment. Two lunar vehicle configurations are reviewed, including design parameters and subsystem development.

A three phase catalytic mathematical model was developed for analysis and optimization of the volatile reactor assembly (VRA) used on International Space Station (ISS) Water Processor. The Langmuir-Hinshelwood Hougen-Watson (L-H) expression was used to describe the surface reaction rate. Small column experiments were used to determine the L-H rate parameters. The test components used in the experiments were acetic acid, acetone, ethanol, 1-propanol, 2-propanol and propionic acid. These compounds are the most prevalent ones found in the influent to the VRA reactor. The VRA model was able to predict performance of small column data and experimental data from the VRA flight experiment.

Flow bench and engine testing can be used to detect flow induced noise, but understanding the fundamental mechanisms of such noise generation is necessary for developing an effective design. This paper describes Computational Aero-Acoustic (CAA) analyses performed to obtain the broad-band and BPF noise sources A computational aero-acoustics simulation on the aerodynamic noise generation of an automotive radiator fan assembly is carried out. Three-dimensional Computational Fluid Dynamics (CFD) simulation of the unsteady flow field was performed including the entire impeller and shroud to obtain the source of an audible broad-band flow noise between 2 to 4 kHz. Static pressure probes placed around the outer-periphery and at the center of the impeller inlet side and, at the shroud cavities to capture the noise sources. The static pressure at all probe locations were FFT (Fast Fourier Transform) processed and sound pressure level (SPL) was calculated.

Urea-selective catalytic reduction (SCR) after-treatment systems are used for reducing oxides of nitrogen (NOx) emissions in medium and heavy duty diesel vehicles. This paper addresses control-oriented modeling, starting from first-principles, of SCR after-treatment systems. Appropriate simplifications are made to yield governing equations of the Urea-SCR. The resulting nonlinear partial differential equations (PDEs) are discretized and linearized to yield a family of linear finite-dimensional state-space models of the SCR at different operating points. It is further shown that this family of models can be reduced to three operating regions. Within each region, parametric dependencies of the system on physical mechanisms are derived. Further model reduction is shown to be possible in each of the three regions resulting in a second-order linear model with sufficient accuracy.

THE Junkers 211B engine follows the usual German practice of very large displacements and conservative mean effective pressures and rotative speeds. However, the relative light weight per unit of displacement results in a net weight per horsepower that is not far above its competitors. Fully automatic devices which control propeller speed, manifold pressure, mixture ratio, spark advance, and supercharger gear ratio follow the German policy of removing all possible distractions from the pilot. This is one of three large liquid-cooled engines known to be produced in quantity in Germany; it powers an impressive percentage of the Luftwaffe. While of external appearance and displacement that resemble the Daimler-Benz DB-601 engine, the fundamental construction, detail design practice, and metallurgy of the Junkers 211B are surprisingly different.

The minimum oxides of nitrogen (NOx) emissions over the U.S. Federal Test Procedure (FTP) using exhaust gas recirculation (EGR) were investigated on a heavy-duty diesel engine featuring a pump-line-nozzle fuel injection system. Due to the technical merits of electronic fuel injection systems, most accounts of EGR system development for heavy-duty diesel engines have focused on these types of engines and not engines with mechanical fuel systems. This work details use of a high-pressure-loop EGR configuration and a novel, computer-controlled, EGR valve that allowed for optimizing the EGR rate as a function of speed and load on a 6L, turbo-charged/intercooled engine. Cycle NOx levels were reduced nearly 50 percent to 2.3 g/hp-hr using conventional diesel fuel and application of only EGR, but particulates increased nearly three-fold even with the standard oxidation catalyst employed.

Future lunar missions will utilize a Lunar DC microgrid (LDCMG) to construct the infrastructure for distributing, storing, and utilizing electrical energy. The LDCMG’s energy management, of which energy storage systems (ESS) are crucial components, will be essential to the success of the missions. Standard system design currently employs a rule-of-thumb approach in which design methodologies rely on heuristics that may only evaluate local power balancing requirements. The Hamiltonian surface shaping and power flow control (HSSPFC) method can also be utilized to analyze and design the lunar LDCMG power distribution network and ESS. In this research, the HSSPFC method will be utilized to determine the ideal energy storage requirements for ESS and the optimally distributed control architecture.

NHTSA is expected to publish a final rule on Interior Head Impact (as an amendment to FMVSS 201) by early 1995. One of the Interior Head Impact Study objectives is to develop a methodology for estimating the minimum head impact space requirements to meet this regulation. The physical parameters affecting the HIC (Head Injury Criterion) are impact velocity, maximum headform stopping distance, peak deceleration, and pulse duration. The equations for estimating the HIC vs. Head Impact Space Requirements are formulated by relating these physical parameters to the Idealized Waveforms of Square Wave, Sine Wave, and Haversine Wave. This methodology has been extended to include the Generic Waveform. Tabulations of Maximum Headform Stopping Distance Requirement vs. Peak Deceleration, Pulse Duration, and HIC for the three Idealized Waveforms at 6.7 m/s (15 mph) impact speed have been generated to provide an estimate of the head impact package space requirement.

It is estimated that operating continuously on a B20 fuel containing the current allowable ASTM specification limits for metal impurities in biodiesel could result in a doubling of ash exposure relative to lube-oil-derived ash. The purpose of this study was to determine if a fuel containing metals at the ASTM limits could cause adverse impacts on the performance and durability of diesel emission control systems. An accelerated durability test method was developed to determine the potential impact of these biodiesel impurities. The test program included engine testing with multiple DPF substrate types as well as DOC and SCR catalysts. The results showed no significant degradation in the thermo-mechanical properties of cordierite, aluminum titanate, or silicon carbide DPFs after exposure to 150,000 mile equivalent biodiesel ash and thermal aging. However, exposure of a cordierite DPF to 435,000 mile equivalent aging resulted in a 69% decrease in the thermal shock resistance parameter.

The process of developing, parameterizing, validating, and maintaining models occurs within a wide variety of tools, and requires significant time and resources. To maximize model utilization, models are often shared between various toolsets and experts. Model integration is typically divided into two categories: model exchange and model co-simulation. Of these two categories, model co-simulation is typically regarded as the more complex and difficult to implement. Co-Simulation provides the ability to integrate models between different toolsets or incompatible versions of the same software. Additionally, it provides the capabilities for real-time simulations and hardware-in-the-loop test scenarios. This paper reviews some of the common co-simulation data communication methods including pipes and file input/output. The differences between serial and parallel, aka synchronous and asynchronous, communication patterns are also discussed.

Excessive interior noise and vibration in propeller driven general aviation aircraft can result in poor pilot communications with ground control personnel and passengers, and, during extended flights, can lead to pilot and passenger fatigue. Noise source/path identification technology applicable to single engine propeller driven aircraft were employed to identify interior noise sources originating from structure-borne engine/propeller vibration, airborne propeller transmission, airborne engine exhaust noise, and engine case radiation. The approach taken was first to conduct a Principal Value Analysis (PVA) of an in-flight noise and vibration database acquired on a single engine aircraft to obtain a correlated data set as viewed by a fixed set of cabin microphones.

Diesel NOx emissions control utilizing combined Lean NOx Trap (LNT) and so-called passive or in-situ Selective Catalytic Reduction (SCR) catalyst technologies (i.e. with reductant species generated by the LNT) has been the subject of several previous papers from our laboratory [ 1 - 2 ]. The present study focuses on hydrocarbon (HC) emissions control via the same LNT+SCR catalyst technology under FTP driving conditions. HC emissions control can be as challenging as NOx control under both current and future federal and California/Green State emission standards. However, as with NOx control, the combined LNT+SCR approach offers advantages for HC emission control over LNT-only aftertreatment. The incremental conversion obtained with the SCR catalyst is shown, both on the basis of vehicle and laboratory tests, to result primarily from HC adsorbed on the SCR catalyst during rich LNT purges that reacts during subsequent lean engine operation.

Cabin air quality is of continuing importance [1]. Contamination of air with particulates or vapors has the potential of affecting the health of passengers and flight crew. Therefore, measures are required to maintain acceptable levels of cabin air quality. One potential source of cabin air contamination is lubricating oils used in the engines. Type II oils are required for the main engines, but Type I or Type II oils can be used for the APU, with Type I recommended by some engine manufacturers for its cold-start properties. Southwest Research Institutes (SwRI®) Department of Emissions Research used an internally developed analytical method called Direct Filter Injection/Gas Chromatograph (DFI/GC™) to analyze for volatile fractions of lubricating oil contaminants on Environmental Control System (ECS) components. Samples of two standard Type II aviation turbine lubricating oils were analyzed with the DFI/GC™ method and their spectra examined.