Engineering topics

Smith, Phillip J.

Publications and source records attributed to Smith, Phillip J..

At least 19 records

NASA NTRS2019

Structural Dynamic Testing Results for Air-Independent Proton Exchange Membrane (PEM) Fuel Cell Technologies for Space Applications

In 2016, the NASA Advanced Exploration Systems (AES) project office funded research at the NASA Glenn Research Center to evaluate the maturity of the Proton Exchange Membrane (PEM) fuel cell technology and its viability for supporting launch vehicle and space applications. This technology evaluation included vibration, reactant purity, and vacuum exposure sensitivity testing. The evaluation process did not include microgravity testing. This paper discusses the vibration sensitivity testing of two air-independent fuel cell stacks provided by different vendors to assess the ability of currently available fuel cell stack hardware to survive the projected random vibrational environment that would be encountered in an upper stage launch vehicle. Baseline performance testing was utilized to quantify stack performance and overboard leak rate at standard atmospheric conditions in order to provide a reference for post-test comparison. Both fuel cell stacks were tested at a random vibration qualification level of 10.4 grms for five minutes in each axis. Low-level sinusoidal sweeps were conducted before and after each random vibration level run to see if any significant change in resonances were detected. Following vibration facility testing, the baseline performance testing was repeated. Test results demonstrated no measurable change in fuel cell electrochemical or mechanical performance, indicating that the two evaluated PEM fuel cell stacks may be suitable for space applications pending microgravity testing.

Gilligan, Ryan P.↗

NASA NTRS2019

Permeation Rate Equations for Hydrogen and Deuterium in a Palladium-Silver Alloy

Mass transfer of a gas through a selective, solid membrane is an effective method for separation of desired species. This selective permeability is evident in the flow of hydrogen and the isotope deuterium through palladium-silver metal alloy media. In this study, based upon Sieverts’s law and the Arrhenius diffusion equation, an empirical correlation was developed to determine the steady-state permeation rate R, dependence on media temperature T, gas supply pressure p(sub S), and gas backpressure p(sub B) on the lower pressure side. Because of an extensive range of experimental conditions and complete reporting of raw data, the research by Ackerman and Koskinas was used as a source for data allowing empirical equation fitting. Unfortunately, those authors reported best-fit equations that poorly represented their own results. To improve the modeling of the original data and demonstrate the quality of the measurements, the current study develops improved hydrogen and deuterium permeation rate equations: P = 4.22×10(exp −6) A[exp(−704/T)](sq. root p(sub S) − sq. root p(sub B))/t for hydrogen P = 2.12×10(exp −6) A[exp(−468/T )](sq. root p(sub S) − sq. root p(sub B))/t for deuterium for values of cross-sectional area A (sq.cm), medium thickness t (cm), pressure p (psia), and temperature T (Kelvin), giving a permeation rate in mole/minute. These equations model permeation rate data more closely than do several other existing literature sources.

Smith, Phillip J.↗

NASA NTRS2019

Characterization of Flat-Plate Heat Pipe Functionality for Fuel Cell Application

For many exothermic systems such as proton exchange membrane (PEM) fuel cells, cooling is necessary to maintain consistent and uniform operating temperatures which are generally in the range of 60 to 80°C. A potential solution is a heat pipe employing the principle of conduction in combination with a phase change. The purpose of this study was to fully characterize the operation of a heat pipe with unique geometry designed for fuel cell heat removal at operating temperatures up to 100°C and to assess the suitability of the resulting performance for cooling system integration. Test variables consist of cold sink thermal contact conductance coefficient improving material usage, heat rejection temperature, contact pressure and area, heat pipe orientation, operational hours, and variability between units. The test results showed that heat pipe performance improves through increased condenser and heat sink contact pressure, thermal contact coating usage, greater condenser area utilization, and colder heat sink temperature. Higher initial heat pipe temperature and greater age or operation time reduce the heat pipe capabilities. Placing the condenser lower than the evaporator is the only heat pipe orientation that affects evaporator plate temperature. Condensing fluid in the lower section reduces heat transfer capacity as that orientation requires liquid water to transport by wicking against gravity.

Smith, Phillip J.↗

NASA NTRS2018

Energy Storage for Lunar Surface Exploration

This paper presents the updated results of a previous NASA study funded under the Advanced Exploration Systems (AES) Modular Power Systems (AMPS) project. This work focuses on generating high-level system sizing relationships for two lunar surface locations that serve as bounding conditions for most other locations. Four critical parameters are considered to provide sizing data: specific energy, energy density, specific power, and power density. Given the energy storage requirements or customer power demand for a lunar mission location, the data presented in this paper provides a method to determine the critical parameter values of a Regenerative Fuel Cell (RFC) system in order to perform high-level mission architecture trades.

surface power systems↗

NASA NTRS2018

Aeronautics Autonomy Testbed Capability (AATC) Team Developed Concepts

In 2015, the National Aeronautics and Space Administration (NASA) formed a multi-center, interdisciplinary team of engineers from three different aeronautics research centers who were tasked with improving NASA autonomy research capabilities. This group was subsequently named the Aeronautics Autonomy Testbed Capability (AATC) team. To aid in confronting the autonomy research directive, NASA contracted IDEO, a design firm, to provide consultants and guides to educate NASA engineers through the practice of design thinking, which is an unconventional method for aerospace design processes. The team then began learning about autonomy research challenges by conducting interviews with a diverse group of researchers and pilots, military personnel and civilians, experts and amateurs. Part of this design thinking process involved developing ideas for products or programs known as concepts that could enable real world fulfillment of the most important latent needs identified through analysis of the interviews. The concepts are intended to be sacrificial, intermediate steps in the design thinking process and are presented in this report to record the efforts of the AATC group. Descriptions are provided in present tense to allow for further ideation and imagining the concept as reality as was attempted during the teams discussions and interviews. This does not indicate that the concepts are actually in practice within NASA though there may be similar existing programs independent of AATC. These concepts were primarily created at two distinct stages during the design thinking process. After the initial interviews, there was a workshop for concept development and the resulting ideas are shown in this work as from the First Round. As part of succeeding interviews, the team members presented the First Round concepts to refine the understanding of existing research needs. This knowledge was then used to generate an additional set of concepts denoted as the Second Round. Some concepts were created by a single person in a few minutes while others were refined by the entire team over several weeks. Thus, certain ideas are more detailed than others but those from the second round are not necessarily more comprehensive than the first round concepts. Primarily, as reported here in the Second Round section, the designs serve to encompass more of the high level end user research needs which were not necessarily known to the team during the prior workshop. In the figures provided throughout this report, illustrations are often provided to represent a concept. Nearly all of the images are informal sketches or renderings and this casualness should, hopefully, not be held to negate the potential insights available within the concepts.

Smith, Phillip J.↗

NASA NTRS2017

Regenerative Fuel Cell Power Systems for Lunar and Martian Surface Exploration

This paper presents the preliminary results of a recent National Aeronautics and Space Administration (NASA) study funded under the Advanced Exploration Systems (AES) Modular Power Systems (AMPS) project. This study evaluated multiple surface locations on both the Moon and Mars, with the goal of establishing a common approach towards technology development and system design for surface power systems that use Regenerative Fuel Cell (RFC) energy storage methods. One RFC design may not be applicable to all surface locations; however, AMPS seeks to find a unified architecture, or series of architectures, that leverages a single development approach to answer the technology need for RFC systems. Early system trades were performed to select the most effective fuel cell and electrolyzer architectures based on current state-of-the-art technology, whereas later trades will establish a detailed system design to enable a near-term ground (non-flight) demonstration. This paper focuses on the initial trade studies, presents the selected fuel cell and electrolyzer architectures for follow-on system design studies, and suggests areas for further technology investment.

lunar and Mars exploration↗

NASA NTRS1999

Alternative Architectures for Distributed Cooperative Problem-Solving in the National Airspace System

The air traffic management system in the United States is an example of a distributed problem solving system. It has elements of both cooperative and competitive problem-solving. This system includes complex organizations such as Airline Operations Centers (AOCs), the FAA Air Traffic Control Systems Command Center (ATCSCC), and traffic management units (TMUs) at enroute centers and TRACONs, all of which have a major focus on strategic decision-making. It also includes individuals concerned more with tactical decisions (such as air traffic controllers and pilots). The architecture for this system has evolved over time to rely heavily on the distribution of tasks and control authority in order to keep cognitive complexity manageable for any one individual operator, and to provide redundancy (both human and technological) to serve as a safety net to catch the slips or mistakes that any one person or entity might make. Currently, major changes are being considered for this architecture, especially with respect to the locus of control, in an effort to improve efficiency and safety. This paper uses a series of case studies to help evaluate some of these changes from the perspective of system complexity, and to point out possible alternative approaches that might be taken to improve system performance. The paper illustrates the need to maintain a clear understanding of what is required to assure a high level of performance when alternative system architectures and decompositions are developed.

Smith, Phillip J.↗

NASA NTRS1996

The Life Cycles of Intense Cyclonic and Anticyclonic Circulation Systems Observed over Oceans

This report presents a summary of research accomplished over the past four years under the sponsorship of NASA grant #NAG8-915. Building on previously funded NASA grants, this part of the project focused on the following specific goals relative to cyclone/anticyclone systems: the jet streak link between block formation and upstream cyclone activity; the role of northward warm air advection in block formation; the importance of cooperative participation of several forcing mechanisms during explosive cyclone development; and the significance of the vertical distribution of forcing processes during cyclone/anticyclone development.

Smith, Phillip J.↗

NASA NTRS1996

A Composite Diagnosis of Synoptic-Scale Extratropical Cyclone Development over the United States

This paper presents a composite diagnosis of synoptic-scale forcing mechanisms associated with extratropical cyclone evolution. Drawn from 12 cyclone cases that occurred over the continental United States during the cool season months, the diagnosis provides a 'climatology' of development mechanisms for difference categories of cyclone evolution ranging from cyclone weakening through three stages of cyclone intensification. Computational results were obtained using an 'extended' form of the Zwack-Okossi equation applied to routine upper-air and surface data analyzed on a 230 km x 230 km grid. Results show that cyclonic vorticity advection, which maximizes in the upper troposphere, was the primary contributor to cyclone development regardless of the stage of development. A second consistent contributor to development was latent heat release. Horizontal temperature advection, often acknowledged as a development mechanism, was found to contribute to development only during more intense stages. During weakening and weaker development stages, temperature advection opposed development, as the warm-air advection invariably found at upper levels was dominated by cold air advection in the lower half of the troposphere. In the more intense stages, development was moderated by dry-adiabatic cooling associated with the ascending vertical motions.

Rolfson, Donald M.↗

NASA NTRS1995

A diagnosis of the development of a winter anticyclone over North America

This paper examines the 48-h life cycle of a winter anticyclone occurring over North America from 18 to 20 January 1979 using Goddard Laboratory for Atmospheres FGGE level 3b (SOP 1) global analyses on a 4 deg latitude by 5 deg longitude grid. Applying the relatively new methodology of the Zwack-Okossi equation, results show that anticyclonic vorticity advection and cold-air advection acted to develop the anticyclone, while adiabatic warming in the descending air opposed development. Other forcing processes made only small contributions to anticyclone changes. Vertical profiles of the development quantities reveal that vorticity and temperature advections, as well as the adiabatic warming, maximized in the 200-300-mb layer.

King, Melinda L.↗

NASA NTRS1995

Planetary and synoptic-scale interactions during the life cycle of a mid-latitude blocking anticyclone over the North Atlantic

The formation of a blocking anticyclone over the North Atlantic has been examined over its entire life-CyCle using the Zwack-Okossi (Z-O) equation as the diagnostic tool. This blocking anticyclone occurred in late October and early November of 1985. The data used were provided by the NASA Goddard Laboratory for Atmospheres on a global 2.O degree latitude by 2.5 degree longitudinal grid. The horizontal distribution of the atmospheric forcing mechanisms that were important to 500 mb block formation, maintenance and decay were examined. A scale-partitioned form of the Z-O equation was then used to examine the relative importance of forcing on the planetary and synoptic scales, and their interactions. As seen in previous studies, the results presented here show that upper tropospheric anticyclonic vorticity advection was the most important contributor to block formation and maintenance. However, adiabatic warming, and vorticity tilting were also important at various times during the block lifetime. In association with precursor surface cyclogenesis, the 300 mb jet streak in the downstream (upstream) from a long-wave trough (ridge) amplified significantly. This strengthening of the jet streak enhanced the anti-cyclonic vorticity advection field that aided the amplification of a 500 mb short-wave ridge. Tile partitioned height tendency results demonstrate that the interactions between the planetary and sn,noptic-scale through vorticity advection was the most important contributor to block formation. Planetary-scale, synoptic-scale. and their interactions contributed weakly to the maintenance of the blocking anticyclone with the advection of synoptic-scale vorticity by the planetary-scale flow playing a more important role. Planetary-scale decay ofthe long-wave ridge contributed to the demise of this blocking event.

Smith, Phillip J.↗

NASA NTRS1994

The life cycles of intense cyclonic and anticyclonic circulation systems observed over oceans

The work over the past six months has focused on the October/November 1985 blocking case study noted in the last progress report. A summary of the results of this effort is contained in the attached preprint papers for the Symposium on the Life Cycles of Extratropical Cyclones. Using this case study as a model, Ph.D. student Anthony Lupo is now initiating the multiple-case diagnosis by first examining two more fall 1985 blocking episodes. In addition, two secondary efforts have been completed, as summarized in the attached M.S. thesis abstracts. Both studies, which were primarily funded by a fellowship and a teaching assistantship, complement the objectives of this study by providing diagnoses of additional cyclone cases to serve as a comparative base for the pre-blocking cyclones to be studied in the multiple-case blocking diagnosis.

Smith, Phillip J.↗

NASA NTRS1993

The life cycles of intense cyclonic and anticyclonic circulation systems observed over oceans

Full attention was now directed to the blocking case studies mentioned in previous reports. Coding and initial computational tests were completed for a North Atlantic blocking case that occurred in late October/early November 1985 and an upstream cyclone that developed rapidly 24 hours before block onset. This work is the subject of two papers accepted for presentation at the International Symposium on the Lifecycles of Extratropical Cyclones in Bergen, Norway, 27 June - 1 July 1994. This effort is currently highlighted by two features. The first is the extension of the Zwack-Okossi equation, originally formulated for the diagnosis of surface wave development, for application at any pressure level. The second is the separation of the basic large-scale analysis fields into synoptic-scale and planetary-scale components, using a two-dimensional Shapiro filter, and the corresponding partitioning of the Zwack-Okossi equation into synoptic-scale, planetary-scale, and synoptic/planetary-scale interaction terms. Preliminary tests suggest substantial contribution from the synoptic-scale and interaction terms.

Smith, Phillip J.↗

NASA NTRS1993

A study of the influence of satellite data on GLA analyses over the Atlantic Ocean during a period of blocking anticyclone development

This paper presents a statistical diagnosis of the differences between two Goddard Laboratory for Atmospheres analysis representations of temperature and wind speed, one containing satellite data influences (SAT analyses) and one without (NOSAT analyses), for a case of oceanic blocking anticyclone development. Results, obtained using area means and standard deviations of the two fields and correlation coefficients and root-mean-square differences between the two fields, indicate that the inclusion of satellite data can have significant impact on ocean-domain analyses. This is especially evident if one examines higher-order fields that represent gradients in the basic variable fields or contain covariances between two different variables (e.g., advections). More specifically, the inclusion of satellite data resulted in a cold (warm) temperature bias at low (high) levels and weaker temperature gradients, stronger winds, weaker vertical wind shears, and a warm-air advection bias at most levels. The SAT analyses also exhibited larger standard deviations than the NOSAT for wind speed, relative vorticity, vorticity advection, temperature advection, and 500-mb height tendencies, suggesting that for this case the spatial variability of the circulation features were enhanced by the inclusion of satellite data. Even so, since height tendencies forced by vorticity and temperature advection were less sensitive to the addition of satellite data than were the advection quantities themselves, the dynamics of the blocking system was apparently less influenced by the presence of satellite data than was the structure of the system.

Lamberty, Gregory L.↗

NASA NTRS1993

Synoptic/planetary-scale interactions and blocking over the North Atlantic Ocean

The central theme of this project has been the diagnosis of blocking anticyclogenesis and the corresponding interactions with synoptic-scale circulations. To that end an extensive investigation of the dynamics and energetics of a major blocking anticyclone and two upstream cyclones, all of which occurred over the North Atlantic Ocean and the United States in January 1979, was undertaken. Data for the study were provided by Goddard Laboratory for Atmospheres (GLA) 4 LAT by 5 LON FGGE analyses. The methodology has primarily focused on the diagnosis of circulation forcing mechanisms using the modified forms (referred to as the extended forms) of the height tendency and Zwack-Okossi equations developed by our research group. Calculations use routine second-order finite differencing with boundary layer fraction and sensible heating and latent heat release represented as parameterized quantities. Of particular interest are the latent heat release estimates, which combine convectional parameterized values with estimates derived from satellite IR data. The latter were obtained using an algorithm derived by Dr. Franklin R. Robertson of NASA's Marshall Space Flight Center. Results are contained in project reports, theses and publications identified in previous review summaries and reports, and publications listed at the end of this summary. Significant accomplishments in the past year are presented.

Smith, Phillip J.↗

NASA NTRS1992

Synoptic/planetary-scale interactions and blocking over the North Atlantic Ocean

The work completed under this grant represents a continuing investigation of synoptic/planetary-scale interactions over the North Atlantic Ocean in late Jan. 1979. The focus of attention was a blocking episode that developed over southern Greenland on 21 Jan. However, the diagnosis also extended to antecedent cyclone activity and the role of moist processes during wave development. In all, the project was partitioned into two phases: (1) an extension of diagnoses that were already in progress of the 21 Jan. blocking episode and its antecedent cyclone activity using satellite-enhanced level 3-b NASA/Goddard Laboratory for Atmospheres (GLA) analyses; and (2) an analysis of the extent to which the results of Phase 1 are sensitive to the presence of satellite information.

Smith, Phillip J.↗

NASA NTRS1992

A diagnosis of the explosive development of two extratropical cyclones

This paper examines the 24-h explosive development periods of two extratropical cyclones, the first occurring over the Gulf Stream off the coast of New England from 18 to 19 January 1979 and the second occurring over the southeastern United States from 20 to 21 January 1979. The data used in this study are the First GARP (Global Atmospheric Research Program) Global Experiment (FGGE) level IIIb (SOP I) global analyses on a 4 deg latitude x 5 deg longitude grid. The parameter used to diagnose development is the geostrophic relative vorticity tendency calculated using an extended form of the Zwack-Okossi development equation. This development equation is similar to the Petterssen-Sutcliffe development equation, but is shown to be more complete by explicitly coupling surface development with forcing at all levels above the surface. Cyclonic-vorticity advection, warm-air advection, and latent heat release act to develop the two cyclones, while adiabatic cooling in the ascending air opposes development. Further, vertical profiles of the development quantities for these two cases reveal that vorticity and temperature advection maximize in the 200-300-mb layer, while the latent heat release maximum is typically below 500 mb.

Lupo, Anthony R.↗

NASA NTRS1992

The diagnosis of a preblocking explosively-developing extratropical cyclone system

This paper presents the diagnosis of an extratropical cyclone that developed explosively from 18 to 19 January 1979 over the North Atlantic Ocean. The diagnosis applies data obtained from the Goddard Laboratory for Atmospheres FGGE SOP-1 level III-b global analyses on a 4 deg latitude by 5 deg longitude grid to the extended height tendency and the Zwack-Okossi development equations. The cyclone developed initially in response to cyclonic vorticity advection downstream from an upper air through, warm air advection in a strongly baroclinic region, and latent heat release in the cyclone domain. As development continued, thermal advection and latent heat release increased their role in forcing height falls in the cyclone domain, while the influence of vorticity advection decreased. Finally, development ceased when anticyclonic vorticity advection below 700 mb and adiabatic cooling in the ascending air combined to neutralize the influence of warm air advection and latent heat release.

Uhl, Mary A.↗