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At least 1,261 records · Page 70
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Lessons Learned From A Cryogenic Motor Configuration Study for Aircraft Propulsion

Cryogenic electric machines are a promising technology for multi megawatt electric aircraft drivetrains. Superconducting stators that make use of low AC loss superconducting wires are considered to be a key component for these cryogenic machines. NASA has undertaken 6-year technical challenge to address this need by designing a 5 MW superconducting motor and cryogenic drive and developing multi-MW prototypes. This poster shares the lessons learned from a completed design study that evaluated several configurations of a 5 MW cryogenic motor for this application. The lessons are drawn from a qualitative study of 16 configurations and a quantitative study of 8 down selected configurations. The quantitative study involved using a motor design code based on analytical calculations (electromagnetic, thermofluid, mechanical, and motor sizing) to determine each configuration’s Pareto front of total efficiency and total specific power. This poster builds upon preliminary results that were previously presented by (1) reporting final results based on a revised design code for each configuration, including a considerable increase in fidelity for a novel radial flux motor and (2) making a down selection of the configuration for future detailed design and demonstration and documenting the rationale for the selection.

Superconductors↗
NASA NTRS1998

Preliminary Assessment of a Neptune Aerocapture Mission Using an Integrated Design Tool

Aerocapture is an efficient orbit insertion technique that uses the planet's atmosphere to decelerate an arriving spacecraft. With current technology and for vehicles of reasonable mass, it is the only technique that might deliver the high delta-V's required for insertion to orbits around the outer planets. Preliminary design studies for outer planet orbital missions must evaluate aerocapture strategies, and must therefore consider the coupling between vehicle geometry, aerodynamics, aerocapture trajectory, heating and thermal protection system mass. The analyses have been linked into an integrated design environment, with the critical parameters grouped in a global database. The designer is free to use single point evaluations, parametric variation, and numerical optimization to evaluate a range of vehicle shapes and insertion trajectories. The application of this design tool to a preliminary study for Neptune aerocapture has implications for the use of such computational environments for any atmospheric entry mission.

Gage, Peter J.↗
NASA NTRS1980

Feasibility study of aileron and spoiler control systems for large horizontal axis wind turbines

The feasibility of using aileron or spoiler controls as alternates to pitch control for large horizontal axis wind turbines was studied. The NASA Mod-0 100 kw machine was used as the basis for the study. Specific performance studies were conducted for 20% chord ailerons over the outboard 30% span, and for 10% chord spoilers over the same portion of the span. Both control systems utilized control deflections up to 60 deg. Results of the study show that either ailerons or spoilers can provide the control necessary to limit turbine power in high wind conditions. The aileron system, as designed, provides overspeed protection at hurricane wind speeds, low wind speed starting torque of 778 N-m (574 ft. lb) at 3.6 m/sec, and a 1.3 to 1.5% increase in annual energy compared to a fixed pitch rotor. The aileron control system preliminary design study includes aileron loads analysis and the design of a failsafe flyweight actuator for overspeed protection in the event of a hydraulic system failure.

Wentz, W. H., Jr.↗
NASA NTRS1995

Design Considerations for the Next Generation of General Aviation Designs

This paper discusses the results of research conducted at NASA Langley Research Center during two summer programs during 1994 and 1995. These programs were the NASA Advanced Design Program and the Langley Research Summer Scholars program. The work was incorporated in a three phase project at Embry-Riddle Aeronautical University which focused on development of the next generation Primary Flight Trainer, as well as in ERAU's participation in the AGATE General Aviation Design Competition. The project was conducted as part of the ERAU/NASA/USRA Advanced Design Program in Aeronautics as well as the AGATE competition. A design study was completed which encompassed the incorporation of existing conventional technologies and advanced technologies into PFT designs and advanced GA aircraft designs. Multiple aircraft configurations were also examined throughout the ADP/AGATE. Evaluations of the various technologies and configurations studied will be made and recommendations will be included.

Marchesseault, Brian D.↗
DOE OSTI2024

Optimized Floating Offshore Wind Turbine Substructure Design Trends for 10–30 MW Turbines in Low-, Medium-, and High-Severity Wave Environments

Floating offshore wind is a promising renewable energy source, as 60% of the wind resources globally are found at depths requiring floating technologies, it minimizes construction at sea, and provides opportunities for industrialization given a lower site dependency. While floating offshore wind has numerous advantages, a current obstacle is its cost in comparison to more established energy sources. One cost-reduction approach for floating wind is increasing turbine capacities, which minimizes the amount of foundations, moorings, cables, and O&M equipment. This work presents trends in mass-optimized VolturnUS hull designs as turbine capacity increases for various wave environments. To do this, a novel rapid hull optimization framework is presented that employs frequency domain modeling, estimations of statistical extreme responses, industry constructability requirements, and genetic algorithm optimization to generate preliminary mass-optimal VolturnUS hull designs for a given turbine design and set of site conditions. Using this framework, mass-optimized VolturnUS hull designs were generated for 10–30 MW turbines for wave environments of varying severities. These design studies show that scaling up turbine capacities increases the mass efficiency of substructure designs, with decreasing returns, throughout the examined turbine capacity range. Additionally, increased wave environment severity is shown to increase the required mass of a given substructure design.

VolturnUS↗
NASA NTRS1974

The design and development of a space laboratory to conduct magnetospheric and plasma research

A design study was conducted concerning a proposed shuttle-borne space laboratory for research on magnetospheric and plasma physics. A worldwide survey found two broad research disciplines of interest: geophysical studies of the dynamics and structure of the magnetosphere (including wave characteristics, wave-particle interactions, magnetospheric modifications, beam-plasma interactions, and energetic particles and tracers) and plasma physics studies (plasma physics in space, wake and sheath studies, and propulsion and devices). The Plasma Physics and Environmental Perturbation Laboratory (PPEPL) designed to perform experiments in these areas will include two 50-m booms and two maneuverable subsatellites, a photometer array, standardized proton, electron, and plasma accelerators, a high-powered transmitter for frequencies above 100 kHz, a low-power transmitter for VLF and below, and complete diagnostic packages. Problem areas in the design of a space plasma physics laboratory are indicated.

Rosen, A.↗
NASA NTRS1978

Application of advanced technologies to small, short-haul aircraft

The results of a preliminary design study which investigates the use of selected advanced technologies to achieve low cost design for small (50-passenger), short haul (50 to 1000 mile) transports are reported. The largest single item in the cost of manufacturing an airplane of this type is labor. A careful examination of advanced technology to airframe structure was performed since one of the most labor-intensive parts of the airplane is structures. Also, preliminary investigation of advanced aerodynamics flight controls, ride control and gust load alleviation systems, aircraft systems and turbo-prop propulsion systems was performed. The most beneficial advanced technology examined was bonded aluminum primary structure. The use of this structure in large wing panels and body sections resulted in a greatly reduced number of parts and fasteners and therefore, labor hours. The resultant cost of assembled airplane structure was reduced by 40% and the total airplane manufacturing cost by 16% - a major cost reduction. With further development, test verification and optimization appreciable weight saving is also achievable. Other advanced technology items which showed significant gains are as follows: (1) advanced turboprop-reduced block fuel by 15.30% depending on range; (2) configuration revisions (vee-tail)-empennage cost reduction of 25%; (3) leading-edge flap addition-weight reduction of 2500 pounds.

Andrews, D. G.↗
NASA NTRS1983

Summary of NASA Langley's pilot scan behavior research

The present investigation is concerned with the information acquired in a series of basic studies designed to obtain an understanding of the pilot's scanning behavior. In the studies, use was made of an oculometer system which operates by shining a beam of collimated infrared light at the subject's eyes. A number of oculometer software modifications have been made to make the oculometer user-friendly and versatile. Scanning is found to be a subconscious conditioned activity. The conditioned activity of scanning is different for each pilot. There are also slight variations between test runs for the same conditions for the same pilot. This indicates that scanning is situation dependent. Attention is given to the rate of information transfer, the possibility that scanning can be disrupted, the visual approach look-point, and workload sensitive measures.

Spady, A. A., Jr.↗
NASA NTRS1984

Geological, structural, and geomorphological analyses from SIR-B

A Shuttle Imaging Radar-B (SIR-B) study designed to develop a better understanding of the application of radar in geological studies is described. The specific objectives for deltaic environments include the examination of delta morphology and the intertidal zone, the surface expression of shallow bathymetry, the characterization of vegetation cover, and the water balance of the delta. In impact crater environments, the goals include the establishment of the radar characteristics of exposed craters and the application of this knowledge to test for the detectability of very poorly exposed craters.

Head, J. W., III↗
NASA NTRS1987

Cosmic ray detectors

Work on the MSFC emulsion laboratory microscopes in which mechanical modifications previously made were verified is reviewed, as is a design study of a large area hybrid electronic/emulsion chamber balloon flight detector system. This design is built upon the experience obtained with the highly successful MSFC/UAH hybrid instrument flown by the JACEE consortium. The design included overall system design and specification, design and fabrication of a prototype large light diffusion for Cerenkov charge detector or scintillator, design of a multiwire proportional counter array and design of the gondola or flight support system.

Gregory, John C.↗
NASA NTRS1989

A study of turbulence near thunderstorm tops

It has been known for many years that turbulence significant for aviation often occurs near thunderstorm tops. However, that turbulence is not well-predicted because of an incomplete understanding of the processes which generate it and because of inadequate observations. The current study seeks to alleviate these problems via: (1) a comprehensive review of recent theoretical and experimental studies related to turbulence near thunderstorm tops (TNTT), and (2) three case studies designed to examine the feasibility of using data derived from commercial aircraft to study TNTT. The literature review revealed extensive evidence which showed that convection often produces significant barrier effects; several mesoscale phenomena capable of producing turbulence may occur, depending on wind and stability conditions near the thunderstorm tops. These include two- and three-dimensional lee waves, rotors, Kelvin-Helmholtz instabilities, and Karman vortices. Conventional meteorological data were combined with data derived from the aircraft flight tapes to produce quantitative descriptions of the turbulence and its mesoscale environment for the three cases.

Pantley, Kim Christine↗
NASA NTRS1989

Numerical model of solar dynamic radiator for parametric analysis

Growth power requirements for Space Station Freedom will be met through addition of 25 kW solar dynamic (SD) power modules. Extensive thermal and power cycle modeling capabilities have been developed which are powerful tools in Station design and analysis, but which prove cumbersome and costly for simple component preliminary design studies. In order to aid in refining the SD radiator to the mature design stage, a simple and flexible numerical model was developed. The model simulates heat transfer and fluid flow performance of the radiator and calculates area mass and impact survivability for many combinations of flow tube and panel configurations, fluid and material properties, and environmental and cycle variations.

Rhatigan, Jennifer L.↗
NASA NTRS1991

Lunar electric power systems utilizing the SP-100 reactor coupled to dynamic conversion systems

An integration study was performed by coupling an SP-100 reactor to either a Brayton or Stirling power conversion subsystem. The application was for a surface power system to supply power requirements to a lunar base. A power level of 550 kWe was selected based on the NASA Space Exploration Initiative 90-day study. Reliability studies were initially performed to determine optimum power-conversion redundancy. This study resulted in selecting three operating engines and one standby unit. Integratiaon-design studies indicated that either the Brayton or Stirling power conversion subsystem could be integrated with the SP-100 reactor. The Stirling system had an integration advantage because of smaller piping size and fewer components. The Stirling engine, however, is more complex and heavier than the Brayton rotating unit, which tends to offset the Stirling integration advantage. From a performance consideration, the Brayton had a 9-percent mass advantage and the Stirling a 50-percent radiator-area advantage.

Harty, Richard B.↗
NASA NTRS1992

Geometric modeling for computer aided design

The goal was the design and implementation of software to be used in the conceptual design of aerospace vehicles. Several packages and design studies were completed, including two software tools currently used in the conceptual level design of aerospace vehicles. These tools are the Solid Modeling Aerospace Research Tool (SMART) and the Environment for Software Integration and Execution (EASIE). SMART provides conceptual designers with a rapid prototyping capability and additionally provides initial mass property analysis. EASIE provides a set of interactive utilities that simplify the task of building and executing computer aided design systems consisting of diverse, stand alone analysis codes that result in the streamlining of the exchange of data between programs, reducing errors and improving efficiency.

Schwing, James L.↗
NASA NTRS1992

Reliability analysis techniques for engine-out failures in main propulsion systems

Reliability formulas are derived for a liquid main propulsion system consisting of n engines, which allows for mission success in the event a single-engine controlled shutdown occurs afer some given time. The formulas include terms to reflect different reliabilities at different engine power levels, startup and throttling reliabilities, benign and catastrophic failures, and failure-distribution scale and shape parameters. These formulas can be used for reliability analyses and sensitivity studies. A parametric launch-vehicle reliability-comparison technique for conceptual preliminary design studies is also described.

Lee, Robert A.↗
NASA NTRS1993

Mixing of a chemically buoyant layer at the top of a thermally convecting fluid: Implications for mantle dynamics with application to Venus

Partial melting to generate the crust of a planet can create a buoyant residual layer at the top of the mantle which may have important implications for episodic planetary evolution. However, the rate of mixing of such a chemically buoyant layer with a thermally convecting mantle is an important unresolved question. Except for a few laboratory and numerical studies designed to address questions related to convection in the Earth's mantle, previous studies have generally treated on the mixing of passive tracers. The inhibiting role of chemical buoyancy on mixing is intuitively obvious but not fully understood quantitatively. In this study, we examine the dynamics of an intrinsically buoyant fluid layer at the top of a deeper, thermally convecting, infinite Prandtl number fluid that is heated from below.

Parmentier, E. M.↗
NASA NTRS1995

Geometric modeling for computer aided design

The primary goal of this grant has been the design and implementation of software to be used in the conceptual design of aerospace vehicles particularly focused on the elements of geometric design, graphical user interfaces, and the interaction of the multitude of software typically used in this engineering environment. This has resulted in the development of several analysis packages and design studies. These include two major software systems currently used in the conceptual level design of aerospace vehicles. These tools are SMART, the Solid Modeling Aerospace Research Tool, and EASIE, the Environment for Software Integration and Execution. Additional software tools were designed and implemented to address the needs of the engineer working in the conceptual design environment. SMART provides conceptual designers with a rapid prototyping capability and several engineering analysis capabilities. In addition, SMART has a carefully engineered user interface that makes it easy to learn and use. Finally, a number of specialty characteristics have been built into SMART which allow it to be used efficiently as a front end geometry processor for other analysis packages. EASIE provides a set of interactive utilities that simplify the task of building and executing computer aided design systems consisting of diverse, stand-alone, analysis codes. Resulting in a streamlining of the exchange of data between programs reducing errors and improving the efficiency. EASIE provides both a methodology and a collection of software tools to ease the task of coordinating engineering design and analysis codes.

Schwing, James L.↗
NASA NTRS1998

A 2 THz Heterodyne Array Receiver for SOFIA

We proposed to perform a comprehensive design study of a 16-element heterodyne array receiver for SOFIA. The array was designed to utilize hot-electron bolometers in an efficient, low-cost waveguide mount to achieve low noise performance between approx. 1500 and 2400 GHz. Due to the prevailing physical conditions in the interstellar medium, this frequency range is one of the richest in the FIR portion of the spectrum. An array designed for this wavelength range will make excellent use of the telescope and the available atmospheric transmission, and will provide a new perspective on stellar, chemical, and galaxy evolution in the present as well as past epochs. A few of the most important molecular and atomic species which the instrument will sample are CII, OI, CO, OH, NII, and CH. The system used the most sensitive detectors available in an efficient optical system. The local oscillator was a compact CO2 pumped far-infrared laser currently under development for SOFIA. The backend spectrometer was an array acousto-optic spectrometer (aAOS). The spectrometer utilizes proven hardware and technologies to provide broadband performance (greater than or equal to 1 GHz per AOS channel) and high spectral resolution (1 MHz) with the maximum sensitivity and minimum complexity and cost. The proposed instrument would be the fastest and most sensitive heterodyne receiver ever to operate in the 1.5 - 2.4 THz band. One of the key technologies developed for the proposed instrument is the laser micromachining of waveguide structures. These structures provide both the optical link between the instrument and the telescope (via an array of efficient feedhorns) and the impedance transformation between the detectors and free space. With the assistance of funds provided from this grant, we were able to fabricate and test the world's first laser micromachined feedhorns. Figure 1 is a photograph of the 2 THz double feedhorn structure designed and constructed under the auspices of this grant. The quality of the waveguide structure is far better than that obtainable using any other fabrication technique. Figure 2 is the beam pattern obtained from it. The beam parameters are an excellent match to what is expected from theory. The success of this experiment demonstrates the viability of using laser micromachined components in the development of high performance, large format array receivers. Figure 3 is an illustration of the focal plane array concept we developed lot- SOFIA base upon this work. Un- fortunately, our instrument proposal was not selected as a first generation SOFIA instrument. However, we have continued our development efforts and will propose to build a 2nd generation instrument based on the same design concepts. Our work under NAG 2-1057 was very rewarding and we appreciate the opportunity provided by NASA to pursue it. The research led directly to publishing 2 papers (listed below) and the award of an NSF grant to our group to construct a laser micromachining system on the University of Arizona campus.

Walker, Christopher K.↗