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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 343 records · Page 19

All sources NASA NTRS DOE OSTI

NASA NTRS1996

Development of a Computer Architecture to Support the Optical Plume Anomaly Detection (OPAD) System

The NASA OPAD spectrometer system relies heavily on extensive software which repetitively extracts spectral information from the engine plume and reports the amounts of metals which are present in the plume. The development of this software is at a sufficiently advanced stage where it can be used in actual engine tests to provide valuable data on engine operation and health. This activity will continue and, in addition, the OPAD system is planned to be used in flight aboard space vehicles. The two implementations, test-stand and in-flight, may have some differing requirements. For example, the data stored during a test-stand experiment are much more extensive than in the in-flight case. In both cases though, the majority of the requirements are similar. New data from the spectrograph is generated at a rate of once every 0.5 sec or faster. All processing must be completed within this period of time to maintain real-time performance. Every 0.5 sec, the OPAD system must report the amounts of specific metals within the engine plume, given the spectral data. At present, the software in the OPAD system performs this function by solving the inverse problem. It uses powerful physics-based computational models (the SPECTRA code), which receive amounts of metals as inputs to produce the spectral data that would have been observed, had the same metal amounts been present in the engine plume. During the experiment, for every spectrum that is observed, an initial approximation is performed using neural networks to establish an initial metal composition which approximates as accurately as possible the real one. Then, using optimization techniques, the SPECTRA code is repetitively used to produce a fit to the data, by adjusting the metal input amounts until the produced spectrum matches the observed one to within a given level of tolerance. This iterative solution to the original problem of determining the metal composition in the plume requires a relatively long period of time to execute the software in a modern single-processor workstation, and therefore real-time operation is currently not possible. A different number of iterations may be required to perform spectral data fitting per spectral sample. Yet, the OPAD system must be designed to maintain real-time performance in all cases. Although faster single-processor workstations are available for execution of the fitting and SPECTRA software, this option is unattractive due to the excessive cost associated with very fast workstations and also due to the fact that such hardware is not easily expandable to accommodate future versions of the software which may require more processing power. Initial research has already demonstrated that the OPAD software can take advantage of a parallel computer architecture to achieve the necessary speedup. Current work has improved the software by converting it into a form which is easily parallelizable. Timing experiments have been performed to establish the computational complexity and execution speed of major components of the software. This work provides the foundation of future work which will create a fully parallel version of the software executing in a shared-memory multiprocessor system.

Katsinis, Constantine↗

NASA NTRS2001

Supersonic Wind Tunnel Tests of a Half-axisymmetric 12 Deg-spike Inlet to a Rocket-based Combined-cycle Propulsion System

Results of an isolated inlet test for NASA's GTX air-breathing launch vehicle concept are presented. The GTX is a Vertical Take-off/ Horizontal Landing reusable single-stage-to-orbit system powered by a rocket-based combined-cycle propulsion system. Tests were conducted in the NASA Glenn 1- by 1-Foot Supersonic Wind Tunnel during two entries in October 1998 and February 1999. Tests were run from Mach 2.8 to 6. Integrated performance parameters and static pressure distributions are reported. The maximum contraction ratios achieved in the tests were lower than predicted by axisymmetric Reynolds-averaged Navier-Stokes computational fluid dynamics (CFD). At Mach 6, the maximum contraction ratio was roughly one-half of the CFD value of 16. The addition of either boundary-layer trip strips or vortex generators had a negligible effect on the maximum contraction ratio. A shock boundary-layer interaction was also evident on the end-walls that terminate the annular flowpath cross section. Cut-back end-walls, designed to reduce the boundary-layer growth upstream of the shock and minimize the interaction, also had negligible effect on the maximum contraction ratio. Both the excessive turning of low-momentum comer flows and local over-contraction due to asymmetric end-walls were identified as possible reasons for the discrepancy between the CFD predictions and the experiment. It is recommended that the centerbody spike and throat angles be reduced in order to lessen the induced pressure rise. The addition of a step on the cowl surface, and planar end-walls more closely approximating a plane of symmetry are also recommended. Provisions for end-wall boundary-layer bleed should be incorporated.

DeBonis, J. R.↗

NASA NTRS2012

The Atomic to Molecular Transition in the Interstellar Medium

Study of H2 in UV and IR continues to surprise us with complexity of excitation state, OPR, and role in astrochemistry. Atomic H in molecular clouds is a very powerful tool suggesting that they are not "young" but that it takes millions of years to convert primarily atomic hydrogen clouds to 99.9% molecular form. Laboratory data suggests that H2 formation is efficient over broader range of temperatures than thought to be the case a few years ago, but range is still limited. Issues of complex grain morphology and surface structure make this a very difficult field in which to obtain definitively meaningful results. Ongoing and future observations of CI and CII will improve our understanding of the structure of clouds, their total mass, and how they have evolved and will continue to do so.

interstellar medium↗

NASA NTRSDate not supplied

NASA’s Earth-Observing Aqua Satellite Mission

NASA’s Earth-observing Aqua satellite was launched into space on May 4, 2002; and since that time, Aqua has been collecting and transmitting data on the Earth’s atmosphere, oceans, land, and ice. These data have contributed to over 20,000 scientific publications cited over 500,000 times in the scientific literature and have been used for numerous practical applications, from weather forecasting to air quality analyses to monitoring such phenomena as forest fires, oil spills, sea ice, dust storms, and volcanic ash plumes. The speaker has been Project Scientist for the Aqua mission since April 1993, starting nine years before the satellite launched. She will give an overview of the mission, a sampling of its results, an estimate of when the mission might end (based on fuel and power limitations), and an indication of the types of tasks that take place largely behind the scenes by the Project Scientist and others to enable such missions to continue and succeed.

Claire L Parkinson↗

NASA NTRS2024

Review and Performance Testing of the Optical Power Monitor (PMON)

The LISA mission requires a high precision optical power monitoring and control system that combines high reliability and measurement accuracy with extremely low disturbance to the core interferometric detection system. NASA is working with Avo Photonics to design and build this optical power monitor, known as PMON. The high-level design requirements take into account detector redundancy, mechanical rigidity, stability against temperature and input alignment changes, parasitic scatter and reflection artifacts, as well as low magnetic field. Gamma and Proton radiation tests have been performed on the photodiodes from a few vendors to verify radiation tolerance. Engineering development units of the PMON have been fabricated, delivered and evaluated at NASA.

Hua Jiao↗

NASA NTRSDate not supplied

Power Optimal Control Allocation for Distributed Electric Propulsion in a Series/Parallel Hybrid Powertrain

This paper describes a thrust allocation scheme that minimizes power consumption in an electrified powertrain with Distributed Electric Propulsion. It takes advantage of an observation about component efficiency maps, that efficiency is often highest at high torque/high speed conditions. This optimal approach is demonstrated to satisfy total thrust and net yaw axis torque requirements, making it suitable for utilizing differential thrust for maneuvering.

electrified aircraft propulsion↗

NASA NTRSDate not supplied

Power Optimal Control Allocation for Distributed Electric Propulsion in a Series/Parallel Hybrid Powertrain

electrified aircraft propulsion↗

NASA NTRS2026

Power Optimal Control Allocation for Distributed Electric Propulsion in a Series/Parallel Hybrid Powertrain

electrified aircraft propulsion↗

NASA NTRS1975

Computed lateral rate and acceleration power spectral response of conventional and STOL airplanes to atmospheric turbulence

Power-spectral-density calculations were made of the lateral responses to atmospheric turbulence for several conventional and short take-off and landing (STOL) airplanes. The turbulence was modeled as three orthogonal velocity components, which were uncorrelated, and each was represented with a one-dimensional power spectrum. Power spectral densities were computed for displacements, rates, and accelerations in roll, yaw, and sideslip. In addition, the power spectral density of the transverse acceleration was computed. Evaluation of ride quality based on a specific ride quality criterion was also made. The results show that the STOL airplanes generally had larger values for the rate and acceleration power spectra (and, consequently, larger corresponding root-mean-square values) than the conventional airplanes. The ride quality criterion gave poorer ratings to the STOL airplanes than to the conventional airplanes.

Lichtenstein, J. H.↗

NASA NTRS2014

Printable Spacecraft: Flexible Electronic Platforms for NASA Missions

Why printed electronics? Why should NASA use printed electronics to make a spacecraft? Three words provide the answer: universal, impactful, progressive. The technology is universal because the applications it can affect are broad and diverse from simple sensors to fully functional spacecraft. The impact of flexible, printed electronics range from straightforward mass, volume and cost savings all the way to enabling new mission concepts. The benefits of the technology will become progressively larger from what is achievable today so that investments will pay dividends tomorrow, next year and next decade. We started off three years ago asking the question can you build an entire spacecraft out of printed electronics? In other words, can you design and fabricate a fully integrated, electronic system that performs the same end-to-end functions of a spacecraft - take scientific measurements, perform data processing, provide data storage, transmit the data, powers itself, orients and propels itself - all out of thin flexible sheets of printed electronics? This "Printable Spacecraft" pushes the limits of printed flexible electronics performance. So the answer is yes, more or less. In our studies for the NIAC (NASA Innovative Advanced Concepts) program, we have explored this question further, to explain more completely what "more or less" means and to outline what is needed to make the answer a definitive "yes". Despite its appealing "Flat Stanley"-like (a book series by Jeff Brown) qualities, making a Printable Spacecraft is not as easy as flattening the Cassini spacecraft with a bulletin board, as was Stanley Lamchop's fate. But, if NASA invests in the design challenges, the materials challenges, the performance challenges of printed electronics, it might find itself with a spacecraft that can enable as many adventures and advantages as Flat Stanley including putting it in an envelope and mailing it to the planet of your choice. You just have to let your imagination take over. In this report we document the work of the Phase 2 Printable Spacecraft task conducted under the guidance and leadership of the NIAC program. In Phase One of the NIAC task entitled "Printable Spacecraft", we investigated the viability of printed electronics technologies for creating multi-functional spacecraft platforms. Mission concepts and architectures that could be enhanced or enabled with this technology were explored. In Phase 2 we tried to answer the more practical questions such as can you really build a multi-functional printed electronic spacecraft system? If you do, can it survive the space environment? Even if it can, what benefit does a printable system provide over a traditional implementation of a spacecraft?

Materials↗

NASA NTRS2006

A Theoretical Solid Oxide Fuel Cell Model for System Controls and Stability Design

As the aviation industry moves towards higher efficiency electrical power generation, all electric aircraft, or zero emissions and more quiet aircraft, fuel cells are sought as the technology that can deliver on these high expectations. The Hybrid Solid Oxide Fuel Cell system combines the fuel cell with a microturbine to obtain up to 70 percent cycle efficiency, and then distributes the electrical power to the loads via a power distribution system. The challenge is to understand the dynamics of this complex multi-discipline system, and design distributed controls that take the system through its operating conditions in a stable and safe manner while maintaining the system performance. This particular system is a power generation and distribution system and the fuel cell and microturbine model fidelity should be compatible with the dynamics of the power distribution system in order to allow proper stability and distributed controls design. A novel modeling approach is proposed for the fuel cell that will allow the fuel cell and the power system to be integrated and designed for stability, distributed controls, and other interface specifications. This investigation shows that for the fuel cell, the voltage characteristic should be modeled, but in addition, conservation equation dynamics, ion diffusion, charge transfer kinetics, and the electron flow inherent impedance should also be included.

Kopasakis, George↗

NASA NTRS2006

Development of an Extra-vehicular (EVA) Infrared (IR) Camera Inspection System

Designed to fulfill a critical inspection need for the Space Shuttle Program, the EVA IR Camera System can detect crack and subsurface defects in the Reinforced Carbon-Carbon (RCC) sections of the Space Shuttle s Thermal Protection System (TPS). The EVA IR Camera performs this detection by taking advantage of the natural thermal gradients induced in the RCC by solar flux and thermal emission from the Earth. This instrument is a compact, low-mass, low-power solution (1.2cm3, 1.5kg, 5.0W) for TPS inspection that exceeds existing requirements for feature detection. Taking advantage of ground-based IR thermography techniques, the EVA IR Camera System provides the Space Shuttle program with a solution that can be accommodated by the existing inspection system. The EVA IR Camera System augments the visible and laser inspection systems and finds cracks and subsurface damage that is not measurable by the other sensors, and thus fills a critical gap in the Space Shuttle s inspection needs. This paper discusses the on-orbit RCC inspection measurement concept and requirements, and then presents a detailed description of the EVA IR Camera System design.

Gazarik, Michael↗

NASA NTRS2026

Parametric-Based Heat Rejection Trade Study for Lunar and Martian Surface Operations

Establishing and maintaining a sustained presence on the lunar and/or Martian surfaces will require a diverse portfolio of surface elements (e.g., habitation, mobility, power generation, etc.). Many of these systems generate excess heat that must be rejected across a wide range of magnitudes, temperatures, and duty cycles and under variable environmental conditions. To identify the most promising heat rejection approaches for this diverse portfolio, a heat rejection trade study was conducted to evaluate the performance of different technology approaches across a spectrum of surface environments and heat-load requirements. The trade study consisted of three stages: (1) development of a parametric-based modeling framework, (2) creation of a database of heat rejection technologies, surface elements, and environmental conditions for the Moon and Mars, and (3) execution of a quantitative analysis of various heat rejection technologies across different operating conditions and surface elements. The modeling framework is developed in Python and Excel to prioritize small model size and hence low computational cost to enable large parametric sweeps while avoiding the reliance on proprietary software. Individual heat rejection processes are represented as simple Excel models, and a centralized Python script interfaces with the models to coordinate the parametric study. These simple sizing models were developed to take heat load requirements and environmental parameters as inputs and compute mass, power, and volume as outputs. Rather than assess each heat rejection technology separately for each surface element, a unified parametric space was developed to evaluate all technologies across all elements. This parametric space includes factors related to heat load (e.g., magnitude or temperature) and environment (e.g., surface temperature, sky temperature, solar flux). This effort generated a database containing information on over 60 heat rejection technologies and 30 surface elements. For each surface element, the expected heat rejection requirements were documented and analyzed to determine the most common needs shared across all elements. Environmental conditions at various lunar and Martian latitudes were also established for worst-case hot and worst-case cold scenarios. High-fidelity heat rejection models are currently under development. Preliminary trades between heat rejection technologies including radiators, venting technologies, convective coolers, and more have been conducted to identify promising options. This presentation will summarize the preliminary trade results and provide an overview and discussion of the expected heat loads and thermal environments for sustained surface operations on the Moon and Mars.

Heat Rejection↗

NASA NTRS2005

Deployable Mini-Payload Missions Enabled by Small Radioisotope Power Systems (RPSs)

Deployable mini-payloads are envisioned as small, simple, standalone instruments that could be deployed from a mother vehicle such as a rover or the proposed Jupiter Icy Moons Orbiter to key points of interest within the solar system. Used in conjunction with a small radioisotope power system (RPS), these payloads could potentially be used for long-duration science missions or as positional beacons for rovers or other spacecraft. The RPS power source would be suitable for deployable mini-payload missions that would take place anywhere there is limited, intermittent, or no solar insolation. This paper introduces two such concepts: (1) a seismic monitoring station deployed by a rover or aerobot, and (2) a passive fields and particles station delivered by a mother spacecraft to Jupiter.

deployables↗

NASA NTRS2018

A Low SWaP-C prototype Ka-band Frequency Synthesizer for Atomic Clocks

We present a low size, weight, power and cost (SWaP-C) prototype circuit of a Ka-band frequency synthesizer. It takes advantage of a phase-locked loop single integrated circuit (IC) and harmonic generation with high speed CMOS gates. We use a direct digital synthesizer (DDS) IC to tune the final output with microHertz resolution. An ultra-low-power micro controller that could serve as the clock controller is used to control the PLL and the DDS. All components are commercial off the shelf (COTS) with acceptable industrial support. The total power consumption is about 1.6 Watt with -45 dBm useful output at 40.507347996 GHz. The short-term instability introduced by the prototype is 7.3E-14 at 1s. The prototyped subsystem uses COTS demonstration boards for the sake of agile prototyping. There is still significant margin for improvement of the size and weight.

Tjoelker, Robert L.↗

NASA NTRS2017

Computational Analysis of Powered Lift Augmentation for the LEAPTech Distributed Electric Propulsion Wing

A computational study of a distributed electric propulsion wing with a 40deg flap deflection has been completed using FUN3D. Two lift-augmentation power conditions were compared with the power-off configuration on the high-lift wing (40deg flap) at a 73 mph freestream flow and for a range of angles of attack from -5 degrees to 14 degrees. The computational study also included investigating the benefit of corotating versus counter-rotating propeller spin direction to powered-lift performance. The results indicate a large benefit in lift coefficient, over the entire range of angle of attack studied, by using corotating propellers that all spin counter to the wingtip vortex. For the landing condition, 73 mph, the unpowered 40deg flap configuration achieved a maximum lift coefficient of 2.3. With high-lift blowing the maximum lift coefficient increased to 5.61. Therefore, the lift augmentation is a factor of 2.4. Taking advantage of the fullspan lift augmentation at similar performance means that a wing powered with the distributed electric propulsion system requires only 42 percent of the wing area of the unpowered wing. This technology will allow wings to be 'cruise optimized', meaning that they will be able to fly closer to maximum lift over drag conditions at the design cruise speed of the aircraft.

Deere, Karen A.↗

NASA NTRS2009

Diagnosis and Reconfiguration using Bayesian Networks: An Electrical Power System Case Study

Automated diagnosis and reconfiguration are important computational techniques that aim to minimize human intervention in autonomous systems. In this paper, we develop novel techniques and models in the context of diagnosis and reconfiguration reasoning using causal Bayesian networks (BNs). We take as starting point a successful diagnostic approach, using a static BN developed for a real-world electrical power system. We discuss in this paper the extension of this diagnostic approach along two dimensions, namely: (i) from a static BN to a dynamic BN; and (ii) from a diagnostic task to a reconfiguration task. More specifically, we discuss the auto-generation of a dynamic Bayesian network from a static Bayesian network. In addition, we discuss subtle, but important, differences between Bayesian networks when used for diagnosis versus reconfiguration. We discuss a novel reconfiguration agent, which models a system causally, including effects of actions through time, using a dynamic Bayesian network. Though the techniques we discuss are general, we demonstrate them in the context of electrical power systems (EPSs) for aircraft and spacecraft. EPSs are vital subsystems on-board aircraft and spacecraft, and many incidents and accidents of these vehicles have been attributed to EPS failures. We discuss a case study that provides initial but promising results for our approach in the setting of electrical power systems.

Knox, W. Bradley↗

NASA NTRS2002

Graph Partitioning for Parallel Applications in Heterogeneous Grid Environments

The problem of partitioning irregular graphs and meshes for parallel computations on homogeneous systems has been extensively studied. However, these partitioning schemes fail when the target system architecture exhibits heterogeneity in resource characteristics. With the emergence of technologies such as the Grid, it is imperative to study the partitioning problem taking into consideration the differing capabilities of such distributed heterogeneous systems. In our model, the heterogeneous system consists of processors with varying processing power and an underlying non-uniform communication network. We present in this paper a novel multilevel partitioning scheme for irregular graphs and meshes, that takes into account issues pertinent to Grid computing environments. Our partitioning algorithm, called MiniMax, generates and maps partitions onto a heterogeneous system with the objective of minimizing the maximum execution time of the parallel distributed application. For experimental performance study, we have considered both a realistic mesh problem from NASA as well as synthetic workloads. Simulation results demonstrate that MiniMax generates high quality partitions for various classes of applications targeted for parallel execution in a distributed heterogeneous environment.

Bisws, Rupak↗