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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 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Data from A Mass Spectrometry-Based High-Throughput Screening Method for Engineering Fatty Acid Synthases with Improved Production of Medium Chain Fatty Acids

Microbial cell factories have been extensively engineered to produce free fatty acids (FFAs) as key components of crucial nutrients, soaps, industrial chemicals, and fuels. However, our ability to control the composition of microbially synthesized FFAs is still limited, particularly, for producing medium‐chain fatty acids (MCFAs). This is mainly due to the lack of high‐throughput approaches for FFA analysis to engineer enzymes with desirable product specificity. Here we report a mass spectrometry (MS)‐based method for rapid profiling of MCFAs in Saccharomyces cerevisiae by using membrane lipids as a proxy. In particular, matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐ToF) MS was used to detect shorter acyl chain phosphatidylcholines from membrane lipids and a higher m/z peak ratio at 730 and 758 was used as an indication for improved MCFA production. This colony‐based method can be performed at a rate of ~2 s per sample, representing a substantial improvement over gas chromatography‐MS (typically >30 min per sample) as the gold standard method for FFA detection. To demonstrate the power of this method, we performed site‐saturation mutagenesis of the yeast fatty acid synthase and identified nine missense mutations that resulted in improved MCFA production relative to the wild‐type strain. Colony‐based MALDI‐ToF MS screening provides an effective approach for engineering microbial fatty acid compositions in a high‐throughput manner.

Conversion↗
DOE OSTI2020

CO 2 chirped-probe-pulse femtosecond CARS thermometry

The application of CO 2 chirped-probe-pulse (CPP) fs coherent anti-Stokes Raman scattering (CARS) for flame thermometry is discussed. A phenomenological model for CO 2 /O 2 CPP fs CARS was developed, and the simulations showed the potential for CO 2 temperature measurements free of interferences from O 2 and with no contribution from the nonresonant background by using a long-time delay for the chirped probe pulse. The accuracy and precision for CO 2 CPP fs CARS thermometry is compared with N 2 CPP fs CARS thermometry for temperatures between 295 K and 1420 K. The measurement accuracy for the CO 2 measurements is comparable with that for the N 2 measurements, while the precision for the CO 2 temperature measurements is significantly better at lower temperatures. In conclusion, we also demonstrate that accurate flame thermometry using a single set of laser parameters can be achieved using the delayed CPP approach.

42 ENGINEERING↗
DOE OSTI2022

Side-lobe reduction by cascading Bragg grating filters on a Si-photonic chip

Bragg-grating based cavities and coupler designs present opportunities for flexible allocation of bandwidth and spectrum in silicon photonic devices. Integrated silicon photonic devices are moving toward mainstream, mass adoption, leading to the need for compact Bragg grating based designs. In this work we present a design and experimental validation of a cascaded contra-directional Bragg-grating coupler with a measured main lobe to side-lobe contrast of 12.93 dB. This level of performance is achieved in a more compact size as compared to conventional apodized gratings, and a similar design philosophy can be used to improve side-lobe reduction in grating-based mirror design for on-chip lasers and other cavity-based designs as well.

42 ENGINEERING↗
DOE OSTI2020

Demonstration of a kilowatt average power, 1 J, green laser

A λ = 515 nm laser generating joule-level pulses at 1 kHz repetition rate was demonstrated by frequency doubling 1.2 J, 2 ns temporally shaped square pulses from a cryogenically cooled Yb:YAG laser in an LBO crystal. A doubling efficiency of 78% resulted in 0.94 J second-harmonic pulses at 1 kHz. The unconverted light interacted with a second LBO crystal to generate > 100 mJ second-harmonic pulses to reach a total green average power of 1.04 kW. A conversion efficiency of 89% was achieved for 0.58 J green pulses at 1 kHz. These results open the possibility to pump high energy femtosecond lasers at kilohertz repetition rates.

42 ENGINEERING↗
DOE OSTI2020

Advanced Data Preparation Module for Metals Additive Manufacturing

The Mission: Provide the LLNL metals additive manufacturing (AM) team with an advanced AM data preparation module that will analyze and optimize build parameters for metal AM parts fabricated in a laser powder bed fusion (LPBF) system in order increase the first pass success ratio.

42 ENGINEERING↗
NASA NTRS1982

Fiber optic wavelength multiplexing for civil aviation applications

Research is being conducted to accelerate the acceptance of advanced technologies by the airframe manufacturers. These technologies will make the aircraft of the 1990-2000 period more efficient and less expensive to operate. The implementation of advanced control functions requires the employment of suitable onboard flight electronics systems. The present investigation is concerned with a concept for reliable onboard data distribution which is focused around the use of fiber optic wavelength division multiplexing (WDM). Attention is given to aircraft control and data distribution, the wavelength division multiplexing data bus, semiconductor lasers and optical transmitters, an optical coupler-multiplexer, and optical demultiplexers. Results of tests on the prototype WDM systems indicate that the WDM concept can be engineered into a successful system with currently available components.

Hendricks, H. D.↗
NASA NTRS1998

LASE validation experiment: preliminary processing of relative humidity from LASE derived water vapor in the middle to upper troposphere

Lidar Atmospheric Sensing Experiment (LASE) is the first fully engineered, autonomous airborne DIAL (Differentials Absorption Lidar) system to measure water vapor, aerosols, and clouds throughout the troposphere. This system uses a double-pulsed Ti:sapphire laser, which is pumped by a frequency-doubled flashlamp-pumped Nd: YAG laser, to transmit light in the 815 mn absorption band of water vapor. LASE operates by locking to a strong water vapor line and electronically tuning to any spectral position on the absorption line to choose the suitable absorption cross-section for optimum measurements over a range of concentrations in the atmosphere. During the LASE Validation Experiment, which was conducted over Wallops Island during September, 1995, LASE operated on either the strong water line for measurements in middle to upper troposphere, or on the weak water line for measurements made in the middle to lower troposphere including the boundary layer. Comparisons with water vapor measurements made by airborne dew point and frost point hygrometers, NASA/GSFC (Goddard Space Flight Center) Raman Lidar, and radiosondes showed the LASE water vapor mixing ratio measurements to have an accuracy of better than 6% or 0.01 g/kg, whichever is larger, throughout the troposphere. In addition to measuring water vapor mixing ratio profiles, LASE simultaneously measures aerosol backscattering profiles at the off-line wavelength near 815 nm from which atmospheric scattering ratio (ASR) profiles are calculated. ASR is defined as the ratio of total (aerosol + molecular) atmospheric scattering to molecular scattering. Assuming a region with very low aerosol loading can be identified, such as that typically found just below the tropopause, then the ASR can be determined. The ASR profiles are calculated by normalizing the scattering in the region containing enhanced aerosols to the expected scattering by the "clean" atmosphere at that altitude. Images of the total ASR clearly depict cloud regions, including multiple cloud layers, thin upper level cirrus, etc., throughout the troposphere. New data products that are being derived from the LASE aerosol and water measurements include: 1) aerosol extinction coefficient, 2) aerosol optical thickness, 3) precipitable water vapor, and 4) relative humidity (RH). These products can be compared with airborne in-situ, and ground and satellite remote sensing measurements,. This paper presents a preliminary examination of RH profiles in the middle to upper troposphere that are generated from LASE measured water vapor mixing ratio profiles coupled with rawinsonde profiles of temperature and pressure.

Brackett, Vincent G.↗
NASA NTRS2011

Using Innovative Technologies for Manufacturing and Evaluating Rocket Engine Hardware

Many of the manufacturing and evaluation techniques that are currently used for rocket engine component production are traditional methods that have been proven through years of experience and historical precedence. As we enter into a new space age where new launch vehicles are being designed and propulsion systems are being improved upon, it is sometimes necessary to adopt new and innovative techniques for manufacturing and evaluating hardware. With a heavy emphasis on cost reduction and improvements in manufacturing time, manufacturing techniques such as Direct Metal Laser Sintering (DMLS) and white light scanning are being adopted and evaluated for their use on J-2X, with hopes of employing both technologies on a wide variety of future projects. DMLS has the potential to significantly reduce the processing time and cost of engine hardware, while achieving desirable material properties by using a layered powdered metal manufacturing process in order to produce complex part geometries. The white light technique is a non-invasive method that can be used to inspect for geometric feature alignment. Both the DMLS manufacturing method and the white light scanning technique have proven to be viable options for manufacturing and evaluating rocket engine hardware, and further development and use of these techniques is recommended.

Betts, Erin M.↗
NASA NTRS2004

Design and Control of a Proof-of-Concept Active Jet Engine Intake Using Shape Memory Alloy Actuators

The design and control of a novel proof-of-concept active jet engine intake using Nickel-Titanium (Ni-Ti or Nitinol) shape memory alloy (SMA) wire actuators is used to demonstrate the potential of an adaptive intake to improve the fuel efficiency of a jet engine. The Nitinol SMA material is selected for this research due to the material's ability to generate large strains of up to 5 percent for repeated operations, a high power-to-weight ratio, electrical resistive actuation, and easy fabrication into a variety of shapes. The proof-of-concept engine intake employs an overlapping leaf design arranged in a concentric configuration. Each leaf is mounted on a supporting bar that rotates upon actuation by SMA wires electrical resistive heating. Feedback control is enabled through the use of a laser range sensor to detect the movement of a leaf and determine the radius of the intake area. Due to the hysteresis behavior inherent in SMAs, a nonlinear robust controller is used to direct the SMA wire actuation. The controller design utilizes the sliding-mode approach to compensate for the nonlinearities associated with the SMA actuator. Feedback control experiments conducted on a fabricated proof-of-concept model have demonstrated the capability to precisely control the intake area and achieve up to a 25 percent reduction in intake area. The experiments demonstrate the feasibility of engine intake area control using the proposed design.

Song, Gangbing↗
DOE OSTI2024

Low-cost Manufacturing of Semitransparent CdTe PV for Building Integration

Solar has been demonstrated to be a robust renewable energy source, constituting a significant portion of the United States’ renewable energy portfolio. Despite its growth across residential, commercial, and utility sectors over the past decades, it remains a small fraction of the overall energy infrastructure. Challenges persist in fully harnessing solar power to meet the nation's escalating energy demands. Among these challenges lies the hurdle of efficiently distributing large quantities of solar-generated electricity to densely populated regions with the highest energy needs and costs. Traditional utility-scale arrays demand extensive land, a luxury often unavailable in metropolitan areas. Consequently, installations must be situated at a distance, necessitating additional infrastructure for electricity transmission to service areas. While metropolitan landscapes lack sprawling open spaces suitable for conventional utility-scale solar deployment, they offer a different resource: windows. Semitransparent photovoltaic window technology has the potential to not only bolster the grid's energy capacity, but to also provide HVAC and economic advantages to building owners. However, commercial availability of building-integrated photovoltaic windows remains limited. Silicon based photovoltaics currently dominate the solar market but adapting them for use in windows poses a variety of engineering and economic challenges such as relatively low power density, high costs associated with custom manufacturing, and aesthetic considerations. Addressing these challenges, this project explored the use of laser ablation patterning to manufacture cost-effective, high-efficiency, semitransparent Cadmium Telluride photovoltaic modules. Results showcased the potential of this methodology in developing photovoltaic windows and other innovative semitransparent PV applications. The ablation manufacturing technique demonstrated great versatility in achieving different patterns and levels of visible light transmission, and the power loss due to ablation was nearly directly proportional to the amount of material removed. Furthermore, the manufacturing process for Cadmium Telluride modules already has established advantages in material and energy efficiency, and the conversion of a standard submodule to semitransparent essentially requires a single additional process step, ensuring scalability. It is important to note that during this work, Toledo Solar experienced substantial organizational upheaval stemming from a lawsuit with First Solar. An external investigation led the board of directors to remove and replace the previous management team, and several other members of the staff elected to depart as well, including the then acting Principle Investigator on this project. The remaining Toledo Solar team attempted to recover from the disruption and deliver on the remaining tasks, but upon its own review, the Department of Energy ruled the project in default and terminated the contract in December 2023.

14 SOLAR ENERGY↗
NASA NTRS1986

Droplet field visualization and characterization via digital image analysis

This paper describes techniques that have been developed at JPL for visualization and measurements of droplet fields in a moving airstream. The techniques have been applied to a variety of problems which include simulation of heavy rain conditions in a wind tunnel, engine ingestion of wheel spray, analysis of fuel nozzle sprays and aerodynamic breakup of non-Newtonian liquids. The approach pursued here is direct imaging using a pulsed laser illumination source, followed by digital processing of photographic images. A laser double pulse technique has been used for determination of droplet velocities. Laser induced fluorescence has been used to enhance droplet definition in photographic images. The image processing software developed is capable of distinguishing between out-of-focus and in-focus drops, retaining only the latter for size determination.

Hernan, M. A.↗
NASA NTRS1991

NASA low-speed centrifugal compressor for 3-D viscous code assessment and fundamental flow physics research

A low speed centrifugal compressor facility recently built by the NASA Lewis Research Center is described. The purpose of this facility is to obtain detailed flow field measurements for computational fluid dynamic code assessment and flow physics modeling in support of Army and NASA efforts to advance small gas turbine engine technology. The facility is heavily instrumented with pressure and temperature probes, both in the stationary and rotating frames of reference, and has provisions for flow visualization and laser velocimetry. The facility will accommodate rotational speeds to 2400 rpm and is rated at pressures to 1.25 atm. The initial compressor stage being tested is geometrically and dynamically representative of modern high-performance centrifugal compressor stages with the exception of Mach number levels. Preliminary experimental investigations of inlet and exit flow uniformly and measurement repeatability are presented. These results demonstrate the high quality of the data which may be expected from this facility. The significance of synergism between computational fluid dynamic analysis and experimentation throughout the development of the low speed centrifugal compressor facility is demonstrated.

Hathaway, M. D.↗
NASA NTRS1991

NASA low-speed centrifugal compressor for 3-D viscous code assessment and fundamental flow physics research

A low speed centrifugal compressor facility recently built by the NASA Lewis Research Center is described. The purpose of this facility is to obtain detailed flow field measurements for computational fluid dynamic code assessment and flow physics modeling in support of Army and NASA efforts to advance small gas turbine engine technology. The facility is heavily instrumented with pressure and temperature probes, both in the stationary and rotating frames of reference, and has provisions for flow visualization and laser velocimetry. The facility will accommodate rotational speeds to 2400 rpm and is rated at pressures to 1.25 atm. The initial compressor stage being tested is geometrically and dynamically representative of modern high-performance centrifugal compressor stages with the exception of Mach number levels. Preliminary experimental investigations of inlet and exit flow uniformly and measurement repeatability are presented. These results demonstrate the high quality of the data which may be expected from this facility. The significance of synergism between computational fluid dynamic analysis and experimentation throughout the development of the low speed centrifugal compressor facility is demonstrated.

Hathaway, M. D.↗