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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
NASA NTRSDate not supplied

Lowering Barriers to Science and Space Weather Research at the Community Coordinated Modeling Center (CCMC)

The Space Weather and Heliophysics research and modeling community has been pushing the limits of our ability to understand and predict space weather events. The Community Coordinated Modeling Center (CCMC, https://ccmc.gsfc.nasa.gov) supports the community by providing a convenient collaborative platform hosting space weather models, model simulation data, curated datasets of solar events, and associated value-added services. Using these services, researchers and other end-users may exercise, evaluate, and intercompare contributed models, triage designated R2O models, as well as collaborate on a continuously updated archive of model run results. We will focus on CCMC’s ongoing commitment to the principles and guidelines of the Open Science initiative. Particularly, we will discuss our work towards making our services more transparent and our library of model simulations more accessible, open, and reproducible. We will introduce our recent tools for data discovery and correlative analysis designed to further increase the value of the user-generated data and metadata. We will also present our recent work on making heliophysical models more accessible and open to the community, particularly through simplified user experience and expert domain support. We will report on our progress in establishing an inter-center infrastructure with the ESA Virtual Space Weather Modelling Centre (VSWMC), designed to cross organizational boundaries and provide streamlined access to a joint palette of the models.

space weather↗
NASA NTRS1990

Transition research using flight experiments

The paper deals with flight experiments as a means of obtaining proper transition information in an uncontaminated environment. Flight transition experiments performed in the early to middle 1950s using rocket-propelled vehicles are outlined. It is noted that the standards for research quality experiments on stability and transition are no different for flight studies than for wind-tunnel experiments. The guidelines formulated by the U.S. Boundary Layer Transition Study Group are listed. Attention is focused on the relationship between the model design and the measurement of disturbance environment, the maintenance and monitoring of test and model-surface conditions, and a need for high data-sampling rates.

Reshotko, Eli↗
NASA NTRS1992

A cloud and radiation model-based algorithm for rainfall retrieval from SSM/I multispectral microwave measurements

A hybrid statistical-physical retrieval scheme is explored which combines a statistical approach with an approach based on the development of cloud-radiation models designed to simulate precipitating atmospheres. The algorithm employs the detailed microphysical information from a cloud model as input to a radiative transfer model which generates a cloud-radiation model database. Statistical procedures are then invoked to objectively generate an initial guess composite profile data set from the database. The retrieval algorithm has been tested for a tropical typhoon case using Special Sensor Microwave/Imager (SSM/I) data and has shown satisfactory results.

Xiang, Xuwu↗
NASA NTRSDate not supplied

A Comprehensive Forward Model for Spaceborne Radar Instruments

We present the development and validation of a comprehensive forward model designed to enhance remote sensing capabilities of spaceborne radar instruments. To overcome limitations in existing models, we integrated a Discrete Dipole Approximation (DDA) cloud scattering database into our Radiative Transfer Model (RTM), focusing on microwave frequencies. By simulating the optical properties of non-spherical frozen hydrometeors, the DDA technique effectively reduced discrepancies between simulated and observed values, surpassing traditional Mie tables. The evaluation of DDA lookup tables involved comparisons with a collocated dataset comprising short-term forecasts and satellite microwave data, providing evidence of their superiority. Additionally, we address the challenges of assimilating active radar measurements, which offer vertically resolved insights into clouds and precipitation. We explored the assimilation of spaceborne radar measurements in Numerical Weather Prediction (NWP) models by integrating a forward radar model, along with its adjoint and tangent linear, into the data assimilation system. Evaluation using CloudSat measurements demonstrated promising agreement between simulations and observations, particularly when the input hydrometeor profiles aligned with the measured reflectivity profiles, showcasing the potential of the developed forward radar model. Moreover, we discuss other challenges in radar measurement assimilation within NWP models, including potential observation errors and biases.

Isaac Moradi↗
NASA NTRS2010

Theoretical Foundation of Copernicus: A Unified System for Trajectory Design and Optimization

The fundamental methods are described for the general spacecraft trajectory design and optimization software system called Copernicus. The methods rely on a unified framework that is used to model, design, and optimize spacecraft trajectories that may operate in complex gravitational force fields, use multiple propulsion systems, and involve multiple spacecraft. The trajectory model, with its associated equations of motion and maneuver models, are discussed.

Ocampo, Cesar↗
NASA NTRS1994

Flutter suppression digital control law design and testing for the AFW wind tunnel model

The design of a control law for simultaneously suppressing the symmetric and antisymmetric flutter modes of a sting mounted fixed-in-roll aeroelastic wind-tunnel model is described. The flutter suppression control law was designed using linear quadratic Gaussian theory, and it also involved control law order reduction, a gain root-locus study, and use of previous experimental results. A 23 percent increase in the open-loop flutter dynamic pressure was demonstrated during the wind-tunnel test. Rapid roll maneuvers at 11 percent above the symmetric flutter boundary were also performed when the model was in a free-to-roll configuration.

Mukhopadhyay, Vivek↗
NASA NTRS2011

Project Report: Design and Analysis for the Deep Space Network BWG Type 2 Antenna Feed Platform

The following report explains in detail the solid modeling design process and structural analysis of the LNA (Low Noise Amplifier) feed platform to be constructed and installed on the new BWG (Beam Wave Guide) Type-2 tracking antenna in Canberra, Australia, as well as all future similar BWG Type-2 antennas builds. The Deep Space Networks new BWG Type-2 antennas use beam waveguides to funnel and 'extract' the desired signals received from spacecraft, and the feed platform supports and houses the LNA(Low Noise Amplifier) feed-cone and cryogenic cooling equipment used in the signal transmission and receiving process. The mandated design and construction of this platform to be installed on the new tracking antenna will be used and incorporated on all future similar antenna builds.

structural analysis software↗
NASA NTRSDate not supplied

Sizing, Buckling, and Thermal-Structural Analysis of Tall Lunar Tower

Tall lunar towers enable direct collection of solar energy using solar panels that can generate power exceeding 100-kW above shadowed regions on the surface. Tall lunar towers also support solar reflectors and concentrators for solar farms, which enable various mission architectures on the lunar surface. The Tall Lunar Tower (TLT) project at NASA Langley Research Center is focused on the design, modeling, fabrication, and testing of an assembled TLT Engineering Development Unit (EDU). In this paper, the design and analysis plan of a TLT is presented and predicted buckling and thermal-structural response of the TLT EDU on the lunar surface are investigated.

Kyongchan Song↗
NASA NTRSDate not supplied

Sizing, Buckling, and Thermal-Structural Analysis of Tall Lunar Tower

Tall lunar towers enable direct collection of solar energy using solar panels that can generate power exceeding 100-kW above shadowed regions on the surface. Tall lunar towers also support solar reflectors and concentrators for solar farms, which enable various mission architectures on the lunar surface. The Tall Lunar Tower (TLT) project at NASA Langley Research Center is focused on the design, modeling, fabrication, and testing of an assembled TLT Engineering Development Unit (EDU). In this paper, the design and analysis plan of a TLT is presented and predicted buckling and thermal-structural response of the TLT EDU on the lunar surface are investigated.

Kyongchan Song↗
NASA NTRS1974

Modeling and analysis of power processing systems: Feasibility investigation and formulation of a methodology

A review is given of future power processing systems planned for the next 20 years, and the state-of-the-art of power processing design modeling and analysis techniques used to optimize power processing systems. A methodology of modeling and analysis of power processing equipment and systems has been formulated to fulfill future tradeoff studies and optimization requirements. Computer techniques were applied to simulate power processor performance and to optimize the design of power processing equipment. A program plan to systematically develop and apply the tools for power processing systems modeling and analysis is presented so that meaningful results can be obtained each year to aid the power processing system engineer and power processing equipment circuit designers in their conceptual and detail design and analysis tasks.

Biess, J. J.↗
NASA NTRS1993

Cruise noise measurements of a scale model advanced ducted propulsor

A scale model Advanced Ducted Propulsor (ADP) was tested in NASA Lewis Research Center's 8- by 6-Foot Wind Tunnel to obtain acoustic data at cruise conditions. The model, designed and manufactured by Pratt & Whitney Division of United Technologies, was tested with three inlet lengths. The model has 16 rotor blades and 22 stator vanes, which results in a cut-on condition with respect to rotor-stator interaction noise. Comparisons of the noise directivity of the ADP with that of a previously tested high-speed, unducted propeller showed that the ADP peak blade passing tone was about 30 dB below that of the propeller, and therefore, should not present a cabin or enroute noise problem. The maximum blade passing tone first increased with increasing helical tip Mach number, peaked, and then decreased at a higher Mach number. The ADP tests with the shortest inlet showed more noise in the inlet arc than did tests with either of the other two inlet lengths.

Dittmar, James H.↗
NASA NTRS2017

Modeling and Measuring Charge-Sharing in Hard X-ray Imagers Using HEXITEC CdTe Detectors

The Rutherford Appleton Laboratory's HEXITEC ASIC has been designed to provide fine pixelated X-ray spectroscopic imaging in combination with a CdTe or CZT detector layer. Although HEXITEC's small pixels enable higher spatial resolution as well as higher spectral resolution via the small-pixel effect, they also increase the probability of charge sharing, a process which degrades spectral performance by dividing the charge induced by a single photon among multiple pixels. In this paper, we investigate the effect of this process on a continuum X-ray spectrum below the Cd and Te fluorescence energies (23 keV). This is done by comparing laboratory measurements with simulations performed with a custom designed model of the HEXITEC ASIC. We find that the simulations closely match the observations implying that we have an adequate understanding of both charge sharing and the HEXITEC ASIC itself. These results can be used to predict the distortion of a spectrum measured with HEXITEC and will help determine to what extent it can be corrected. They also show that models like this one are important tools in developing and interpreting observations from ASICs like HEXITEC.

Ryan, Daniel F.↗
NASA NTRS2017

Relating a Jet-Surface Interaction Experiment to a Commercial Supersonic Transport Aircraft Using Numerical Simulations

Reynolds-Averaged Navier-Stokes (RANS) simulations were performed for a commercial supersonic transport aircraft concept and experimental hardware models designed to represent the installed propulsion system of the conceptual aircraft in an upcoming test campaign. The purpose of the experiment is to determine the effects of jet-surface interactions from supersonic aircraft on airport community noise. RANS simulations of the commercial supersonic transport aircraft concept were performed to relate the representative experimental hardware to the actual aircraft. RANS screening simulations were performed on the proposed test hardware to verify that it would be free from potential rig noise and to predict the aerodynamic forces on the model hardware to assist with structural design. The simulations showed a large region of separated flow formed in a junction region of one of the experimental configurations. This was dissimilar with simulations of the aircraft and could invalidate the noise measurements. This configuration was modified and a subsequent RANS simulation showed that the size of the flow separation was greatly reduced. The aerodynamic forces found on the experimental models were found to be relatively small when compared to the expected loads from the model’s own weight.Reynolds-Averaged Navier-Stokes (RANS) simulations were completed for two configurations of a three-stream inverted velocity profile (IVP) nozzle and a baseline single-stream round nozzle (mixed-flow equivalent conditions). For the Sideline and Cutback flow conditions, while the IVP nozzles did not reduce the peak turbulent kinetic energy on the lower side of the jet plume, the IVP nozzles did significantly reduce the size of the region of peak turbulent kinetic energy when compared to the jet plume of the baseline nozzle cases. The IVP nozzle at Sideline conditions did suffer a region of separated flow from the inner stream nozzle splitter that did produce an intense, but small, region of turbulent kinetic energy in the vicinity of the nozzle exit. When viewed with the understanding that jet noise is directly related to turbulent kinetic energy, these IVP nozzle simulations show the potential to reduce noise to observers located below the nozzle. However, these RANS simulations also show that some modifications may be needed to prevent the small region of separated flow-induced turbulent kinetic energy from the inner stream nozzle splitter at Sideline conditions.

Reynolds-Averaged Navier Stokes↗
NASA NTRS1974

Wind-tunnel investigation of an externally blown flap STOL transport model including and investigation of wall effects

A wind-tunnel investigation was conducted in the Langley V/STOL tunnel and in a scaled version of the Ames 40- by 80-foot tunnel test section installed as a liner in the Langley V/STOL tunnel to determine the effect of test-section size on aerodynamic characteristics of the model. The model investigated was a swept-wing, jet-powered, externally blown flap (EBF) STOL transport configuration with a leading-edge slat and triple-slotted flaps. The model was an 0.1645-scale model of a 11.58-meter (38.0-ft) span model designed for tests in a 40- by 80-foot tunnel. The data compare the aerodynamic characteristics of the model with and without the tunnel liner installed. Data are presented as a function of thrust coefficient over an angle-of-attack range of 0 deg to 25 deg. A thrust-coefficient range up to approximately 4.0 was simulated, most ot the tests being conducted at a free-stream dynamic pressure of 814 Newtons/sq m (17 lb sq ft). The data are presented with a minimum of analysis.

Gentry, G. L., Jr.↗
NASA NTRS1977

Force testing manual for the Langley 20-inch Mach 6 tunnel

Data reduction and procedures for conducting force tests in a 20 inch Mach 6 tunnel are described. A discussion of pretest and testing phases are included. Items that are to be checked during model design and construction are outlined as well as safety requirements, starting loads tests, instructions for data acquisition and model installation. Measurement of balance and model misalignment and instructions for calibrating the angle of attack screen are covered. Procedures for making reference pressure, attitude tare, and data runs are included. The 20 inch tunnel force program is examined, and a description of data recording system input and load contrast sheets is given. An appendix presents a description, operating characteristics, and Mach number calibration of the tunnel, as well as tunnel characteristics.

Keyes, J. W.↗
NASA NTRS1958

Measurements of the Buffeting Loads on the Wing and Horizontal Tail of a 1/4-scale Model of the X-1E Airplane

The buffeting loads acting on the wing and horizontal tail of a 1/4-scale model of the X-1E airplane have been measured in the Langley 16-foot transonic tunnel in the Mach number range from 0.40 to 0.90. When the buffeting loads were reduced to a nondimensional aerodynamic coefficient of buffeting intensity, it was found that the maximum buffeting intensity of the horizontal tail was about twice as large as that of the wing. Comparison of power spectra of buffeting loads acting on the horizontal tail of the airplaneand of the model indicated that the model horizontal tail, which was of conventional force-test-model design, responded in an entirely different mode than did the airplane.This result implied that if quantitative extrapolation of model data to flight conditions were desired a dynamically scaled model of the rearward portion of the fuselage and empennage would be required. A study of the sources of horizontal-tail buffeting of the model indicated that the wing wake contributed a large part of the total buffeting load. At one condition it was found that removal of the wing wake would reduce the buffeting loads on the horizontal tail to about one-third of the original value.

Rainey, A Gerald↗
NASA NTRS1993

Intelligent systems and advanced user interfaces for design, operation, and maintenance of command management systems

Historically, command management systems (CMS) have been large and expensive spacecraft-specific software systems that were costly to build, operate, and maintain. Current and emerging hardware, software, and user interface technologies may offer an opportunity to facilitate the initial formulation and design of a spacecraft-specific CMS as well as to develop a more generic CMS system. New technologies, in addition to a core CMS common to a range of spacecraft, may facilitate the training and enhance the efficiency of CMS operations. Current mission operations center (MOC) hardware and software include Unix workstations, the C/C++ programming languages, and an X window interface. This configuration provides the power and flexibility to support sophisticated and intelligent user interfaces that exploit state-of-the-art technologies in human-machine interaction, artificial intelligence, and software engineering. One of the goals of this research is to explore the extent to which technologies developed in the research laboratory can be productively applied in a complex system such as spacecraft command management. Initial examination of some of these issues in CMS design and operation suggests that application of technologies such as intelligent planning, case-based reasoning, human-machine systems design and analysis tools (e.g., operator and designer models), and human-computer interaction tools (e.g., graphics, visualization, and animation) may provide significant savings in the design, operation, and maintenance of the CMS for a specific spacecraft as well as continuity for CMS design and development across spacecraft. The first six months of this research saw a broad investigation by Georgia Tech researchers into the function, design, and operation of current and planned command management systems at Goddard Space Flight Center. As the first step, the researchers attempted to understand the current and anticipated horizons of command management systems at Goddard. Preliminary results are given on CMS commonalities and causes of low re-use, and methods are proposed to facilitate increased re-use.

Potter, William J.↗