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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 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

A Transformational Natural Gas Fueled Dynamic SOFC for Data Center in-Rack Power (Final Technical Report)

Data centers consume 250TWh or 1% of global electricity use in 2019. This electricity demand is expected to grow exponentially in the future. The current data center power supply relies on electric grids with diesel engines and batteries as backup; the latter is critically important because a sudden loss of power could erase crucial data, causing catastrophic economic loss. However, such a double protection architecture is costly, inefficient and polluting. In search for better in-rack power system, fuel-cell based generators have recently emerged as a promising alternative to diesel engines and batteries because of its potential to be more cost-effective, more efficient and less polluting. Among many types of fuel cells, solid oxide fuel cells stand out to be a front runner because of their ability to directly operate on natural gas that has an existing infrastructure. However, there are several critical challenges facing SOFC generators to meet the rigorous power requirements of data centers: high cost, poor reliability and more importantly, slow response to the datacenters’ dynamic load change. The unexpected overload conditions in data centers can cause fuel starvation; the latter can initiate microcracks in the anode structure, thus jeopardizing the lifetime of the SOFC generator. The current efforts to increase transient power capabilities of traditional SOFCs and therefore protect SOFC stacks from internal damage during transient loading, rely primarily upon mathematical algorithms. One of the challenges to these control methodologies is the physical limitations of the fuel delivery system such as slow response of mass flow controllers to fast power demand.

30 DIRECT ENERGY CONVERSION↗
NASA NTRS1991

A spacecraft charging study on the SCEX 3 rocket

Instruments on the SCEX 3 rocket payload were used to study charging during electron beam emissions. The data show that electrostatic analyzers can be used to measure vehicle charging and direct beam return currents in dense plasma conditions. The data also show return current dependencies on pitch angle, beam current and beam energy. It is found that if the proper care is taken, ESAs can be used to detect charging on vehicles in low altitude orbits which are contaminated with high levels of outgassing and in dense plasma regimes. These results are particularly important for the TSS-1 electrodynamic tether program where ESAs are being used to determine Shuttle charging levels during tether employment and to look for high fluxes of directly returning electrons during electron generator operations to balance the Shuttle charging.

Mullen, E. G.↗
NASA NTRS2016

Biomechanical Modeling of the Deadlift Exercise to Improve the Efficacy of Resistive Exercise Microgravity Countermeasures

During long-duration spaceflight missions, astronauts exposure to microgravity without adequate countermeasures can result in losses of muscular strength and endurance, as well as loss of bone mass. As a countermeasure to this challenge, astronauts engage in resistive exercise during spaceflight to maintain their musculoskeletal function. The Hybrid Ultimate Lifting Kit (HULK) has been designed as a prototype exercise device for an exploration-class vehicle; the HULK features a much smaller footprint than previous devices such as the Advanced Resistive Exercise Device (ARED) on the International Space Station (ISS), which makes the HULK suitable for extended spaceflight missions in vehicles with limited volume. As current ISS exercise countermeasure equipment represents an improvement over previous generations of such devices, the ARED is being employed as a benchmark of functional performance. This project involves the development of a biomechanical model of the deadlift exercise, and is novel in that it is the first exercise analyzed in this context to include the upper limbs in the loading path, in contrast to the squat, single-leg squat, and heel raise exercises also being modeled by our team. OpenSim software is employed to develop these biomechanical models of humans performing resistive exercises to assess and improve the new exercise device designs. Analyses include determining differences in joint and muscle forces when using different loading strategies with the device, comparing and contrasting with the ARED benchmark, and determining whether the loading is sufficient to maintain musculoskeletal health. During data collection, the number of repetitions, load, cadence, stance, and grip width are controlled in order to facilitate comparisons between loading configurations. To date, data have been collected for two human subjects performing the deadlift exercise on the HULK device using two different loading conditions. Recorded data include motion capture, electromyography (EMG), ground reaction forces, device load cell data, photos and videos, and anthropometric data. Work is ongoing to perform biomechanical analyses including inverse kinematics and inverse dynamics to compare different versions of the deadlift model in order to determine which provides an appropriate level of detail to study this exercise. This work is supported by the National Space Biomedical Research Institute through NCC 9-58.

physical exercise↗
DOE OSTI2025

Identifying rolling resistance and air resistance simultaneously for an electric truck

Accurately estimating rolling and air resistance is essential for predicting the energy consumption of vehicles. This study presents a field-based approach using a rolldown test to simultaneously determine rolling and air resistance coefficients. Unlike prior methods that frequently used simulations or models, we employ a goal programming methodology to improve precision and evaluate the actual vehicle and environmental conditions. Our methodology was tested using a Class 8 Freightliner eCascadia on a surveyed road section, ensuring controlled conditions for data collection. By analyzing the time–velocity relationship across multiple test runs, we derived resistance coefficients for both loaded and unloaded conditions. The study confirms that rolling resistance is largely independent of velocity at low speeds but exhibits a nonlinear dependency at higher speeds. Additionally, road surface conditions, tire condition, axle configuration, aerodynamic properties, and weather conditions significantly impact resistance values, emphasizing the need for real-world testing rather than relying solely on standardized projections. Our results align with existing literature while demonstrating the efficacy of the goal programming approach in refining resistance estimates. This work contributes to improved vehicle energy modeling, offering practical insights for fleet operators and policymakers seeking accurate energy consumption predictions for electric trucks operating under varying environmental conditions.

47 OTHER INSTRUMENTATION↗
NASA NTRS1975

Gravitational Harmonics from Shallow Resonant Orbits

Five gravitational constraints were derived for the GEOS 2 orbit (order 13, to 30th degree) whose principal resonant period is 6 days. The constraints explain the sinusoidal variation with argument of perigee of a lumped harmonic found from 41 6-day arcs of optical and laser data. The condition equations, derived from elementary perturbation theory are shown to account for almost all of the resonant information in the tracking data.

Wagner, C. A.↗
NASA NTRS1959

Exploratory Investigation of Aerodynamic Flameholders for Afterburner Application

An investigation was conducted to determine the flameholding capabilities of aerodynamic jets at afterburner operating conditions. Stability data for a number of aerodynamic flameholders were obtained in a 5- by 5-inch test section at inlet-air reference velocities up to 600 feet per second, an inlet-air temperature of 1250 F, and a combustor-inlet pressure of 15 inches of mercury absolute. Combustion efficiency and stability data of the more promising combinations were then obtained in a 10- by 12-inch test section at the same test conditions. Both air and stoichiometric mixtures of fuel and air were used in the jets; mixture flow rates were approximately 1 percent by weight of the total air-flow rate. Injection pressures were limited to values that might be available from compressor-bleed air. At a reference velocity of 600 feet per second, aerodynamic flame-holders alone were unable to maintain a stable flame at injection pressures up to 70 pounds per square inches large reductions in velocity were required to achieve flame stabilization. When the aerodynamic jets were used in combination with a V-gutter flameholder with approximately a 30 percent blocked area, flame stabilization was attained at a velocity of 600 feet per second; however, the combustion efficiencies of the various combinations were no greater than that obtained with the V-gutter alone.

Butze, Helmut F.↗
NASA NTRS2008

Ice Shape Scaling for Aircraft in SLD Conditions

This paper has summarized recent NASA research into scaling of SLD conditions with data from both SLD and Appendix C tests. Scaling results obtained by applying existing scaling methods for size and test-condition scaling will be reviewed. Large feather growth issues, including scaling approaches, will be discussed briefly. The material included applies only to unprotected, unswept geometries. Within the limits of the conditions tested to date, the results show that the similarity parameters needed for Appendix C scaling also can be used for SLD scaling, and no additional parameters are required. These results were based on visual comparisons of reference and scale ice shapes. Nearly all of the experimental results presented have been obtained in sea-level tunnels. The currently recommended methods to scale model size, icing limit and test conditions are described.

Anderson, David N.↗
NASA NTRS2010

Positive Voltage Hazard to EMU Crewman from Currents through Plasma

This paper describes the model of the EMU with a human body in the circuit that has been used by NASA to evaluate the low positive voltage hazard. The model utilizes the electron collection characterization from on orbit Langmuir probe data as representative of electron collection to a positive charged surface with a wide range of on orbit plasma temperature and density conditions. The data has been unified according to non-linear theoretical temperature and density variation of the electron saturated probe current collection theory and used as a model for the electron collection at EMU surfaces. Vulnerable paths through the EMU connecting through the crewman s body have been identified along with electrical impedance of the exposed body parts. The body impedance information is merged with the electron collection characteristics in circuit simulation software (SPICE). The assessment shows that currents can be on the order of 20 mA for a 15 V exposure and of order 4 mA at 3V. These currents formally violate NASA protocol for electric current exposures however the human factors associated with subjective consequences of noxious stimuli from low voltage exposure during the stressful conditions of EVA are an area of active inquiry.

Koontz, Steven L.↗
NASA NTRS1979

Analysis and test for space shuttle propellant dynamics (1/10th scale model test results). Volume 2: 1/10th scale model test data

Thirty sets of test data selected from the 89 low-g aircraft tests flown by NASA KC-135 zero-g aircraft are listed in tables with their accompanying test conditions. The data for each test consists of the time history plots of digitalized data (in engineering units) and the time history plots of the load cell data transformed to the tank axis system. The transformed load cell data was developed for future analytical comparisons; therefore, these data were transformed and plotted from the time at which the aircraft Z axis acceleration passed through l-g. There are 14 time history plots per test condition. The contents of each plot is shown in a table.

Berry, R. L.↗
NASA NTRS1976

Noise generated by impingement of turbulent flow on airfoils of varied chord, cylinders, and other flow obstructions

Noise spectra were measured in three dimensions for several surfaces immersed in turbulent flow from a jet and over a range of flow conditions. The data are free field and were corrected to remove the small contributions of jet noise, atmospheric attenuation and feedback tones. These broadband data were compared with the results of available theories which are only strictly applicable to simple geometries over a limited range of conditions. The available theories proved to be accurate over the range of flow, chord length, thickness, angle of attack, and surface geometries defined by the experiments. These results apply to the noise generated by fixed surfaces in engine passages, the lifting surfaces of aircraft and also to fan noise.

Olsen, W. A.↗
NASA NTRS1976

Noise generated by impingement of turbulent flow on airfoils of varied chord, cylinders, and other flow obstructions

Noise spectra were measured in three dimensions for several surfaces immersed in turbulent flow from a jet and over a range of flow conditions. The data are free field and were corrected to remove the small contributions of jet noise, atmospheric attenuation and feedback tones. These broadband data were compared with the results of available theories which are only strictly applicable to simple geometries over a limited range of conditions. The available theories proved to be accurate over the range of flow, chord length, thickness, angle of attack, and surface geometries defined by the experiments. These results apply to the noise generated by fixed surfaces in engine passages, the lifting surfaces of aircraft and also to fan noise.

Olsen, W. A.↗
NASA NTRS1977

Computer assisted thermal-vacuum testing

In testing complex systems and components under dynamic thermal-vacuum environments, it is desirable to optimize the environment control sequence in order to reduce test duration and cost. This paper describes an approach where a computer is utilized as part of the test control operation. Real time test data is made available to the computer through time-sharing terminals at appropriate time intervals. A mathematical model of the test article and environmental control equipment is then operated on using the real time data to yield current thermal status, temperature analysis, trend prediction and recommended thermal control setting changes to arrive at the required thermal condition. The data acquisition interface and the time-sharing hook-up to an IBM-370 computer is described along with a typical control program and data demonstrating its use.

Petrie, W.↗
NASA NTRS1994

Reduction of Helicopter BVI Noise, Vibration, and Power Consumption Through Individual Blade Control

A wind tunnel test was conducted with a full-scale BO 105 helicopter rotor to evaluate the potential of open-loop individual blade control (IBC) to improve rotor performance, to reduce blade vortex interaction (BVI) noise, and to alleviate helicopter vibrations. The wind tunnel test was an international collaborative effort between NASA/U.S. Army AFDD, ZF Luftfahrttechnik, Eurocopter Deutschland, and the German Aerospace Laboratory (DLR) and was conducted under the auspices of the U.S./German MOU on Rotorcraft Aeromechanics. In this test the normal blade pitch links of the rotor were replaced by servo-actuators so that the pitch of each blade could be controlled independently of the other blades. The specially designed servoactuators and IBC control system were designed and manufactured by ZF Luftfahrttechnik, GmbH. The wind tunnel test was conducted in the 40- by 80-Foot Wind Tunnel at the NASA Ames Research Center. An extensive amount of measurement information was acquired for each IBC data point. These data include rotor performance, static and dynamic hub forces and moments, rotor loads, control loads, inboard and outboard blade pitch motion, and BVI noise data. The data indicated very significant (80 percent) simultaneous reductions in both BVI noise and hub vibrations could be obtained using multi-harmonic input at the critical descent (terminal approach) condition. The data also showed that performance improvements of up to 7 percent could be obtained using 2P input at high-speed forward flight conditions.

Jacklin, Stephen A.↗
DOE OSTI2023

Air Conditioning Systems Fault Detection and Diagnosis-Based Sensing and Data-Driven Approaches

The air conditioning (AC) system is the primary building end-use contributor to the peak demand for energy. The energy consumed by this system has grown as fast as it has in the last few decades, not only in the residential section but also in the industry and transport sectors. Therefore, to combat energy crises, urgent actions on energy efficiency should be taken to support energy security. Consequently, the faults in AC system components increase energy consumption due to the degradation of the system’s performance and the losses in the energy conversion procedure. In this work, AC system fault detection and diagnosis (FDD) methods are investigated to propose analytic tools to identify faults and provide solutions to those problems. The analysis of existing work shows that data-driven approaches are more accurate for both soft and hard fault detection and diagnosis in AC systems. Therefore, the proposed methods are not accurate for simultaneous fault detection, while in some works, authors tested the method with several faults separately without investigating scenarios that combine more than one fault. Moreover, this study shows that integrating data-driven approaches requires deploying an optimal sensing and measurement architecture that can detect a maximum number of faults with minimally deployed sensors. The new sensing, information, and communication technologies are discussed for their integration in AC system monitoring in order to optimize system operation and detect faults.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1997

Cryogenic Tunnel Pressure Measurements on a Supercritical Airfoil for Several Shock Buffet Conditions

Steady and unsteady experimental data are presented for several fixed geometry conditions from a test in the NASA Langley 0.3-Meter Transonic Cryogenic Tunnel. The purpose of this test was to obtain unsteady data for transonic conditions on a fixed and pitching supercritical airfoil at high Reynolds numbers. Data and brief analyses for several of the fixed geometry test conditions will be presented here. These are at Reynolds numbers from 6 x 10(exp 6) to 35 x 10(exp 6) bases on chord length, and span a limited range of Mach numbers and angles of attack just below and at the onset of shock buffet. Reynolds scaling effects appear in both the steady pressure data and in the onset of shock buffet at Reynolds numbers of 15 x 10(exp 6) and 3O x 10(exp 6) per chord length.

Bartels, Robert E.↗
DOE OSTI2026

Evaluating the limitations of Bayesian metabolic control analysis

Bayesian Metabolic Control Analysis (BMCA) is a promising framework for inferring metabolic control coefficients in data-limited scenarios, combining Bayesian inference with linear-logarithmic (lin-log) rate laws. These metabolic control coefficients quantify how changes in enzyme activities affect steady-state fluxes and metabolite concentrations across a metabolic network. However, its predictive accuracy and limitations remain underexplored. This study systematically evaluates BMCA’s ability to infer elasticity values, flux control coefficients (FCC), and concentration control coefficients (CCC) under varying data availability conditions using three synthetic metabolic network models. We demonstrate that BMCA predictions are highly dependent on the inclusion of flux and enzyme concentration data, with the omission of these datasets leading to severe inaccuracies. In our synthetic, enzyme-perturbation datasets, external metabolite concentrations had minimal impact and, in some cases, their exclusion improved predictions; when external-nutrient perturbations were introduced and those concentrations were observed, gains were at most modest. Additionally, we find that posterior estimation with both ADVI and HMC can underestimate large-magnitude elasticities in our synthetic settings, with ADVI showing somewhat higher variance under strong up-regulation; thus, recovering |elasticity| ≳ 1.5 remains challenging regardless of the inference engine. ADVI also fails to accurately infer allosteric interactions, even when regulatory effects are strong. While BMCA maintains reasonable accuracy in partially recovering the rankings of the highest FCC values, its estimates of absolute values remain constrained by prior assumptions and data limitations. Our findings reveal the BMCA algorithm’s strengths and weaknesses, providing guidance on its application in metabolic engineering, and highlighting the need for methodological refinements to enhance its predictive capabilities.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS2014

External Vision Systems (XVS) Proof-of-Concept Flight Test Evaluation

NASA's Fundamental Aeronautics Program, High Speed Project is performing research, development, test and evaluation of flight deck and related technologies to support future low-boom, supersonic configurations (without forward-facing windows) by use of an eXternal Vision System (XVS). The challenge of XVS is to determine a combination of sensor and display technologies which can provide an equivalent level of safety and performance to that provided by forward-facing windows in today's aircraft. This flight test was conducted with the goal of obtaining performance data on see-and-avoid and see-to-follow traffic using a proof-of-concept XVS design in actual flight conditions. Six data collection flights were flown in four traffic scenarios against two different sized participating traffic aircraft. This test utilized a 3x1 array of High Definition (HD) cameras, with a fixed forward field-of-view, mounted on NASA Langley's UC-12 test aircraft. Test scenarios, with participating NASA aircraft serving as traffic, were presented to two evaluation pilots per flight - one using the proof-of-concept (POC) XVS and the other looking out the forward windows. The camera images were presented on the XVS display in the aft cabin with Head-Up Display (HUD)-like flight symbology overlaying the real-time imagery. The test generated XVS performance data, including comparisons to natural vision, and post-run subjective acceptability data were also collected. This paper discusses the flight test activities, its operational challenges, and summarizes the findings to date.

Shelton, Kevin J.↗
NASA NTRS1975

Usefulness of LANDSAT data for monitoring plant development and range conditions in California's annual grassland

A network of sampling sites throughout the annual grassland region of California was established to correlate plant growth stages and forage production to climatic and other environmental factors. Plant growth and range conditions were further related to geographic location and seasonal variations. A sequence of LANDSAT data was obtained covering critical periods in the growth cycle. This was analyzed by both photointerpretation and computer aided techniques. Image characteristics and spectral reflectance data were then related to forage production, range condition, range site and changing growth conditions. It was determined that repeat sequences with LANDSAT color composite images do provide a means for monitoring changes in range condition. Spectral radiance data obtained from magnetic tape can be used to determine quantitatively the critical stages in the forage growth cycle. A computer ratioing technique provided a sensitive indicator of changes in growth stages and an indication of the relative differences in forage production between range sites.

Carneggie, D. M.↗